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How is the scientific method used to solve problems?
Scientific method used to solve problems by keen observations, rational analysis, and experimentation.
How is the scientific method used to solve problems?
Scientific method used to solve problems by keen observations, rational analysis, and experimentation.
An educated guess or a reasonable explanation. When the hypothesis can be tested by experiment, it qualifies as a scientific hypothesis
Consequences that can be observed if the hypothesis is correct. The consequences should be absent if the hypothesis is not correct.
Formulate the simplest general rule that organizes the hypothesis, predicted effects, and experimental findings.
What is the principle of falsifiability?
For a hypothesis to be considered scientific it must be testable?it must, in principle, be capable of being proven wrong.
A synthesis of a large body of information that encompasses well-tested hypotheses about certain aspects of the natural world.
A general hypothesis or statement about the relationship of natural quantities that has been tested over and over again and has not been contradicted. Also known as a principle.
is a test carried out in order to discover whether a theory is correct or what the results of a particular course of action would be .
What did Galileo do to challenge Aristotle?s belief that heavy objects fall faster than lighter objects?
Galileo very carefully examined Aristotle?s hypothesis. Then he did something that caught on and changed science forever. He experimented. Galileo showed the falseness of Aristotle?s claim with a single experiment?dropping heavy and light objects from the Leaning Tower of Pisa. Legend tells us that they fell at equal speeds. In the scientific spirit, one experiment that can be reproduced outweighs any authority, regardless of reputation or the number of advocates.
How are systems used to study science/biology?
As per the definition of systems that it is a combination of related parts organized into a complex whole. The Scientists studies the thousands of genes and their protein products. And research how the activities of these myriad molecules are coordinated in the development and maintenance of cells and whole organisms. And this research is now the approach called system biology.
What is the difference between inductive and deductive reasoning?
Deductive reasoning involves moving from generalities to specifics by working through a series of reasoned statements. Inductive reasoning, on the other hand, takes a series of specific observations and tries to expand them into a more general theory.
How is creativity used in science?
Creativity is used in Science by involving mental process through creative problem solving and the discovery of new ideas or concepts, or new associations of the existing ideas or concepts, fuelled by the process of either conscious or unconscious insight. From a scientific point of view, the products of creative thought (sometimes referred to as divergent thought) are usually considered to have both originality and appropriateness. Although intuitively a simple phenomenon, it is in fact quite complex. It has been studied from the perspectives of behavioural psychology, social psychology, psychometrics, cognitive science, artificial intelligence, philosophy, aesthetics, history, economics, design research, business, and management, among others. The studies have covered everyday creativity, exceptional creativity and even artificial creativity. Unlike many phenomena in science, there is no single, authoritative perspective or definition of creativity. And unlike many phenomena in psychology, there is no standardized measurement technique
How are hypotheses used in scientific inquiry?
For a hypothesis to be considered scientific it must be testable?it must, in principle, be capable of being proven wrong then a scientific inquiry will be started. Scientific inquiry have two functions: first, to provide a descriptive account of how scientific inquiry is carried out in practice, and second, to provide an explanatory account of why scientific inquiry succeeds as well as it appears to do in arriving at genuine knowledge of its objects basing on the formulation of the hypothesis. The classical model of scientific inquiry derives from Aristotle, who distinguished the forms of approximate and exact reasoning, set out the threefold scheme of abductive, deductive, and inductive inference, and also treated the compound forms such as reasoning by analogy.
What elements are important when designing a controlled experiment?
Elements of challenge, adventure, and surprise along with careful planning, reasoning, creativity, cooperation, competition, patience and the persistence ,to overcome setbacks.
What's the difference between a hypothesis and a theory?
When a scientific hypothesis has been tested over and over again and has not been contradicted, it may become known as a law or principle. While the scientific theory is a synthesis of facts and well tested hypotheses.
What is the relationship between science and technology?
Science is concerned with gathering knowledge and organizing it. Technology lets humans use that knowledge for practical purposes, and it provides the instruments scientists need to conduct their investigations.
Explain how field studies are used in science.
Field study is used in Science by naturalists for the scientific study of free-living wild animals in which the subjects are observed in their natural habitat, without changing, harming, or materially altering the setting or behaviour of the animals under study. Field study is an indispensable part of biological science. It helps to reveal the habits and habitats of various organisms present in their natural surroundings.
the scientific study of matter, energy, force, and motion, and the way they relate to each other. Physics traditionally incorporates mechanics, electromagnetism, optics, and thermodynamics and now includes modern disciplines such as quantum mechanics, relativity, and nuclear physics.
the study of the structure of the Earth or another planet, especially its rocks, soil, and minerals, and its history and origins
a science that deals with the Earth's physical properties, structure, or development,
the scientific study of the universe, especially of the motions, positions, sizes, composition, and behaviour of astronomical objects. These objects are studied and interpreted from the radiation they emit and from data gathered by interplanetary probes
What is the goal of using an integrated approach to study science?
give you a background in the sciences-Physics, Chemistry, Earth Sciences and Biology-to make you scientifically literate for today's technical world
Explain the limitations of science.
There are three primary areas for which science can't help answer questions. All of these have the same problem: The questions they present don't have testable answers. Since testability is so vital to the scientific process, these questions simply fall outside the venue of science. Science can't answer questions about value; Science can't answer questions of morality, finally, science can't help us with questions about the supernatural.
Explain the limitations of a scientific investigation.
Science deals only with hypotheses that are testable. Its domain is therefore restricted to the observable natural world. While scientific methods can be used to debunk various paranormal claims, they have no way of accounting for testimonies involving the supernatural. The term supernatural literally means ?above nature.? Science works within nature, not above it. Likewise, science is unable to answer philosophical questions, such as ?What is the purpose of life?? or religious questions, such as ?What is the nature of the human spirit?? Though these questions are valid and may have great importance to us, they rely on subjective personal experience and do not lead to testable hypotheses.
How does biology integrate other disciplines? Give an example.
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Integration of biology with other disciplines is recognized on the basis of the scale at which organisms are studied and the methods used to study them. Example is the Molecular biology. It is the study of biology at a molecular level. This field overlaps with other areas of biology, particularly with genetics and biochemistry. Molecular biology chiefly concerns itself with understanding the interactions between the various systems of a cell, including the interrelationship of DNA, RNA, and protein synthesis and learning how these interactions are regulated.
Describe the themes that unify biology.
1. Cell- The cells are every organism's basic units of structure and function. 2. Heritable Information - The continuity of life depends on the inheritance of biological information in the form of DNA molecules. This genetic information is encoded in the nucleotide sequences of the DNA. 3. Emergent properties of Biological Systems - The living world hsa a hierarchical organization, extending from molecules to the biosphere. 4. Regulation - Feedback mechanisms regulate biological systems. 5. Interaction with the environment - Organisms are open systems that exchange material and energy with their surroundings. 6. Energy and life - All organisms must perform work, which requires energy. 7. Unity and Diversity - Three domains of life: Bacteria, Archaea and Eukarya 8. Evolution - Core theme, explains both the unity and the diversity of life. 9. Structure and function - Form and function are correlated at all levels of biological organization. 10. Scientific inquiry - the process of Science includes observation-based discovery and the testing of explanations through hypothesis-based inquiry. 11. Science, Technology and society - many technologies are goal-oriented applications of Science.
The basic unit of liquid volume or capacity in the metric system, equal to 1.06 quart or 2.12 pints.
Average speed. is a unit of speed or velocity, expressing the number of kilometers traveled in one hour
a measure of acidity or alkalinity in which the pH of pure water is 7, with lower numbers indicating acidity and higher numbers indicating alkalinity.
unit of force equivalent to the force that produces an acceleration of one meter per second per second on a mass of one kilogram
the unit of electromotive force and electric potential difference equal to the difference between two points in a circuit carrying one ampere of current and dissipating one watt of power
unit of electrical resistance, equal to the resistance between two points on a conductor when a potential difference of 1 volt produces a current of 1 ampere.
unit of energy or work, equal to the work done when the application point of a one Newton force moves one meter in the direction of application
The unit of mass. One kilogram (symbol kg) is the mass of 1 liter (symbol L) of water at .4 degrees C.
unit of absolute temperature, equal to 1/273.16 of the absolute temperature of the triple point of water, equivalent to one degree Celsius
Grams per cubic centimeter (g/cm3):
unit of length, equivalent to approximately 1.094 yd or 39.37 in.
unit of power equal to the power produced by a current of one ampere acting across a potential difference of one volt.
unit of power equal to the power produced by a current of one ampere acting across a potential difference of one volt.
How does a simple machine affect force output?
By accomplishing one or more of the following functions: 1. transferring a force from one place to another, 2. changing the direction of a force, 3. increasing the magnitude of a force, or 4. increasing the distance or speed of a force.
What is the difference between force output and work output?
A force output is the force that is exerted from the input force to create motion of the resisting object. The input force can be less or more then the output force while the work output is the energy output, which for simple machines is always less than the energy input, even though the forces might be drastically different.
What is the mechanical advantage of using each type of simple machines?
1. Lever ? the mechanical advantage of a lever is the ratio of the length of the lever on the applied force side of the fulcrum to the length of the lever on the resistance force side of the fulcrum. 2. Wheel and Axle -The mechanical advantage of a wheel and axle is the ratio of the radius of the wheel to the radius of the axle 3. Pulley-The mechanical advantage of a moveable pulley is equal to the number of ropes that support the moveable pulley. 4. Inclined Plane -The mechanical advantage of an inclined plane is equal to the length of the slope divided by the height of the inclined plane. 5. Wedge -The mechanical advantage of a wedge can be found by dividing the length of either slope (S) by the thickness (T) of the big end. 6. Screw-the total mechanical advantage is equal to the circumference of the simple machine to which the effort force is applied divided by the pitch of the screw.
Explain what happens to the gravitational force when there is a change in mass and/or distance.
The greater the distance from Earth?s centre, the less the gravitational force on an object. In Newton?s equation for gravity, the distance term d is the distance between the centers of the masses of objects attracted to each other. But no matter how great the distance, gravity approaches, but never quite reaches, zero. There is still a gravitational attraction between any two masses, no matter how far apart they are. Gravity gets weaker with distance the same way a light gets dimmer as you move farther from it.
Use an example to explain the inverse-square law.
Ex. In a typical classroom with a teachers voice signal of 65 decibels at a three-foot distance from the teacher; at 6 feet away the sound intensity will be 59 decibels and at twelve feet it will diminish down to 53 decibels.
What is projectile motion?
A projectile motion involves two components of motion ? vertical and horizontal. Characteristically, motion in one direction is independent of motion in another direction.
How does an object become a satellite?
If an apple or anything else moves fast enough so that it?s curved path matches the Earth?s curvature, it becomes a satellite.
What happens to a satellite when its speed exceeds 8 km/s?
For speeds higher than 8 km/s, the satellite's orbit is elliptical instead of circular. If speed exceeds 11.2 km/s then the satellite escapes Earth because gravity weakens (as object gets further away) and never slows the satellite enough to return it back towards Earth.
Explain the role of gravity in the formation of solar systems and galaxies.
Planets, stars, galaxies and solar systems are formed because of gravity. Planets are formed when pieces of debris are gravitationally attracted, so they compact together to make a bigger piece. More and more material is attracted until object is huge. Now that the planet is massive enough, its gravity is strong enough to pull everything down to a center point, making the planet spherical. Stars are formed when a nebulae gasses compact because of gravity. The temperature reaches a minimum of 18,000,000°F, nuclear fusion begins and a star is formed. Gravity turns the star spherical just like it does to planets. A solar system, is a group of planets and other object such as comets and meteors that orbit a central star, like our sun. A solar system is gravitationally bound together. All the planets and object are gravitationally bound. The central star keeps everything in orbit around it, because of gravity. So the universe is only possible because of gravity.
List the ways that gravity affects the objects in the solar system.
The solar system is made up of the sun, its planets, natural satellites, asteroids, meteoroids, and comets. Each of these bodies are held to each other by the force of gravity The planets move almost in circular elliptical orbits based on the force of gravity. The sun's gravitational pull is the most powerful gravitational force in the solar system. The other heavenly bodies have a much smaller gravitational force on one another called perturbations. The planets orbit the sun in the same counterclockwise direction
Why does the same side of the Moon always face the Earth?
The Moon in fact does spin, although quite slowly?about once every 27 days. This monthly rate of spin matches the rate at which the Moon revolves about Earth.
Explain the relationship between thermal energy and gravitational force in a star?s life cycle.
Gravitational force between the gaseous particles in a protostar results in an overall contraction of this huge ball of gas, and its density increases still further as matter is crunched together, with an accompanying rise in pressure and temperature. When the central temperature reaches about 10 million K, hydrogen nuclei begin fusing to form helium nuclei. This thermonuclear reaction, converting hydrogen to helium, releases an enormous amount of radiant and thermal energy. The ignition of nuclear fuel marks the change from protostar to star.
How does gravity affect light in a black hole?
A black hole is the remains of a supergiant star that has collapsed into itself. It is so dense and has such an intense gravitational field that light cannot escape from it. We can see why gravity is so great in the vicinity of a black hole by considering the change in the gravitational field at the surface of any star that collapses.
How does gravitational field affect light (refer to the footnote on p. 658)?
Light, just like massive things, is affected by gravity. Just as we fail to see the curvature of a high-speed bullet when viewed along short segments, we most often fail to see the curvature by gravity of even higher speed light. Light does curve in a gravitational field.
What is the electrical force?
The electrical force, like gravitational force, decreases inversely as the square of the distance between the charges. This relationship, which was discovered by Charles Coulomb in the eighteenth century, is called Coulomb?s Law. It states that, for two charged objects that are much smaller than the distance between them, the force between them varies directly as the product of their charges and inversely as the square of the separation distance. The force acts along a straight line from one charge to the other.
Explain the conservation of charge.
The principle that the total electric charge of an isolated system remains constant, no matter what internal changes take place.
How is Coulomb?s law regarding electrical force similar to Newton?s law of universal gravitation?
Coulomb?s Law of electrical force, like gravitational force of Newton?s law, decreases inversely as the square of the distance between the charges.
How does Coulomb?s law differ from Newton?s law of universal gravitation?
The most important difference between gravitational force of Newton?s law and electrical forces of Coulomb?s law is that electrical forces may be either attractive or repulsive, whereas gravitational forces are only attractive
Describe the inverse-square law.
is any physical law stating that some physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity.
What happens when a charged particle enters an electric field?
If you place a charged particle in an electric field, it will experience a force. The direction of the force on a positive charge is the same direction as the field.
How can electric potential energy increase?
If the particle is released, it accelerates in a direction away from the sphere, and its electric potential energy changes to kinetic energy, thus increases the electric potential energy
Explain what volt means when referring to a nine-volt battery.
It means that one of the battery terminals is 9V higher in potential than the other one. It also means that, when a circuit is connected between these terminals, each coulomb of charge in the resulting current will be given 9 J of energy as it passes through the battery (and 9 J of energy is ?spent? in the circuit).
Explain why glass is an insulator whereas silver is a conductor.
Silver is a good electrical conductor for the same reason they are good heat conductors: atoms of metals have one or more outer electrons that are loosely bound to their nuclei. These are called free electrons. It is these free electrons that conduct through a metallic conductor when an electric force is applied to it, making up a current. The electrons in a glass are tightly bound and belong to particular atoms. Consequently, it isn?t easy to make them flow. These materials are poor electrical conductors for the same reason they are generally poor heat conductors. Such a material is called a good insulator
Why is a potential difference needed for an electric current?
When the ends of an electrical conductor are at different electric potentials? when there is a potential difference?charges in the conductor flow from the higher potential to the lower potential. The flow of charges persists until both ends reach the same potential. Without a potential difference, no flow of charge will occur.
What is an ampere?
An ampere is the rate of flow of 1 coulomb of charge per second. (That?s a flow of 6.25 billion billion electrons per second.)
Alternating current (AC).
is electric current that repeatedly reverses its direction; the electric charges vibrate about relatively fixed positions. In the United States, the vibrational rate is 60 Hz
Explain the relationship between current, resistance, and voltage in Ohm?s law.
the amount of current in a circuit is directly proportional to the voltage established across the circuit and is inversely proportional to the resistance of the circuit
What is a resistor?
a component of an electrical circuit that has resistance and is used to control the flow of electric current
How does a parallel circuit differ from a series circuit?
Components connected in series are connected along a single path, so the same current flows through all of the components. Components connected in parallel are connected so the same voltage is applied to each component. In a series circuit, the current through each of the components is the same, and the voltage across the components is the sum of the voltages across each component while in a parallel circuit, the voltage across each of the components is the same, and the total current is the sum of the currents through each component.
How does magnetic force differ from electric force?
Whereas electric charges produce electrical forces, regions called magnetic poles give rise to magnetic forces. The difference is that electric charges can be isolated, magnetic poles cannot. Electrons and protons are entities by themselves. But the north and south poles of a magnet are like the head and tail of the same coin. If you break a bar magnet in half, each half still behaves as a complete magnet. Break the pieces in half again, and you have four complete magnets. You can continue breaking the pieces in half and never isolate a single pole. Even if your pieces were one atom thick, there would still be two poles on each piece, which suggests that the atoms themselves are magnets
Explain what makes an object magnetic.
in the electrons of the atoms that make up the object magnetic. These electrons are in constant motion. Two kinds of electron motion produce magnetism: electron spin and electron revolution. In most common magnets, electron spin is the main contributor to magnetism. Every spinning electron is a tiny magnet. A pair of electrons spinning in the same direction creates a stronger magnet.
How does a compass work?
The compass functions as an indicator to "Magnetic North" because the magnetic bar at the heart of the compass aligns itself to one of the lines of the Earth's magnetic field.
What is an electromagnet?
A magnet consisting of a core, often made of soft iron that is temporarily magnetized by an electric current flowing through a coil that surrounds it
Describe how moving charges interact with a magnetic field.
A magnetic field is produced by moving electric charges.
Why does a magnet deflect a current-carrying wire?
A charged particle has to be moving to interact with a magnetic field. Charges at rest don?t respond to magnets. But, when they are moving, charged particles experience a deflecting force. The force is greatest when the particles move at right angles to the magnetic field lines. At other angles, the force is less, and it becomes zero when the particles move parallel to the field lines. The force is always perpendicular to the magnetic field lines and perpendicular to the velocity of the charged particle. So a moving charge is deflected when it crosses through a magnetic field, but, when it travels parallel to the field, no deflection occurs.
Explain electromagnetic induction.
the induction of voltage when a magnetic field changes with time.
How do electric motors work?
An electric motor uses electrical energy to produce mechanical energy, very typically through the interaction of magnetic fields and current-carrying conductors. An electric motor is all about magnets and magnetism: A motor uses magnets to create motion. The fundamental law of all magnets: Opposites attract and likes repel. So if you have two bar magnets with their ends marked "north" and "south," then the north end of one magnet will attract the south end of the other. On the other hand, the north end of one magnet will repel the north end of the other (and similarly, south will repel south). Inside an electric motor, these attracting and repelling forces create rotational motion.
What is potential energy?
The energy that a body or system has stored because of its position in an electric, magnetic, or gravitational field, or because of its configuration. Symbol VEp
Chemical potential energy
Example: fossil fuel like coal. The energy is only released when a chemical reaction takes place, ie burning it with oxygen.
Explain what happens to kinetic energy when the mass and speed of an object changes.
Kinetic energy also changes because the kinetic energy of an object depends on its mass and its speed. It is equal to half the mass multiplied by the square of the speed, multiplied by the constant ½.
List examples of different types of kinetic energy.
A car moving along a road has kinetic energy, Energy can be transferred from one object to another, such as when a rolling bowling ball transfers some of its kinetic energy to the pins and sets them in motion. Energy also transforms, or changes form. For example, the gravitational potential energy of a raised ram transforms to kinetic energy when the ram is released from its elevated position. And, when you raise a pendulum bob against the force of gravity, you do work on it. That work is stored as potential energy until you let the pendulum bob go. Its potential energy transforms to kinetic energy as it picks up speed and loses elevation.
Explain the law of conservation of energy.
Whenever energy is transformed or transferred, none is lost and none is gained. In the absence of work input or output, the total energy of a system before some process or event is equal to the total energy after.
Define thermal energy.
Energy resulting from the motion of particles. Thermal energy is a form of kinetic energy and is transferred as heat.
Newton?s first law of motion
Every object continues in a state of rest, or in a state of motion in a straight line at a constant speed, unless it is compelled to change that state by forces exerted on it.
Newton?s second law of motion
The acceleration produced by a net force on an object is directly proportional to the net force, is in the same direction as the net force, and is inversely proportional to the mass of the object.
Newton?s third law of motion
whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object.
Newton?s First Law of Motion-
Examples: 1. when you play tug of war. As one side pulls on the other, there is sometimes no motion at all. But there are forces are work. Those forces are balanced a and so though there is force, there is no motion. 2. a moving car will stop if it hits another moving car, but not if you step on the floorboard because stepping on the floorboard is an internal force. 15 3. You may push a piano and it may not move. That is because the force of gravity uses the weight of the piano as a type of force that keeps balance unless an outside force or external force creates an imbalance. The harder you push, the more of a chance you have of creating an unbalanced force. If you push hard enough you will create an unbalanced force and the piano
Newton?s Second Law of Motion-
Examples: 1. if you are pushing on an object, causing it to accelerate, andthen you push, say, three times harder, the acceleration will be three times greater. 2. if you are pushing equally on two objects, and one of the objects has five times more mass than the other, it will accelerate at one fifth the acceleration of the other. 3. if a train hits another train of equal force and speed, they will both go the same distance and feel the same force. But if the first train is hooked to a second, the single train will go twice the distance of the double train and will feel twice the force.
Newton?s Third Law of Motion-
Examples: 1. A classic example is any rocket launch. A chemical reaction occurs in the rocket engine. The engine pushes out gases at a very high pressure from the bottom of the engine. This is the action. The gases in turn, exert an upward force on the rocket propelling it in the opposite (upward) direction - into space. This is the reaction. 2. While swimming or rowing, your hands / oars push the water behind - Action. The water pushes you in the opposite (forward) direction - Reaction. 3. A bird pushes air down while flying (action), Since forces result from mutual the air must also be pushing the bird upwards (equal and opposite reaction). This allows the bird to fly
What is a wave?
A disturbance that travels from one place to another transporting energy, but not necessarily matter, along with it.
the modulation of the amplitude of a radio wave in such a way as to encode the wave with audio or visual information.
The distance from the top of one crest to the top of the next one or, equivalently, the distance between successive identical parts of the wave.
The number of to-and-fro vibrations an oscillator makes in a given time, or the number of times a particular point on a wave (for example the crest) passes a given point in a given time.
The time required for a vibration or a wave to make a complete cycle; a horizontal row in the periodic table.
Summarize radio waves.
AM radio waves are usually measured in kilohertz, while FM radio waves are measured in megahertz. These radio-wave frequencies are the frequencies at which electrons are forced to vibrate in the antenna of a radio station?s transmitting tower. The frequency of the vibrating electrons and the frequency of the wave produced are the same.
A wave in which the medium vibrates in a direction perpendicular (transverse) to the direction in which the wave travels
A wave in which the medium vibrates in a direction parallel (longitudinal) with the direction in which the wave travels. Compressions and rarefactions are characteristics of longitudinal waves.
transverse (an example)
Water waves. The water moves up and down while the wave travels over the surface of the water.
longitudinal waves (an example)
Sound waves. The air vibrates back and forth along the same direction as the wave is traveling.
What changes the pitch of sound?
The rate of vibration of air molecules next to a vibrating object changes the pitch of sound.
Explain how different factors affect the speed of sound?
The speed of sound depends on wind conditions, temperature, and humidity. It does not depend on the loudness or the frequency of the sound; all sounds travel at the same speed in a given medium. The speed of sound in dry air at 0°C is about 330 meters per second, which is nearly 1200 kilometers per hour. Water vapor in the air increases this speed slightly. Sound travels faster through warm air than cold air. because the faster-moving molecules in warm air bump into each other more frequently and, therefore, can transmit a pulse in less time.* For each degree rise in temperature above 0°C, the speed of sound in air increases by 0.6 meter per second. Thus, in air at a normal room temperature of about 20°C, sound travels at about 340 meters per second. In water, sound speed is about four times its speed in air; in steel, it?s about fifteen times its speed in air.
Why do submerged objects appear to be nearer the surface than they actual are?
Refraction causes many illusions. One of them is the apparent bending of a stick that is partially submerged in water. The submerged part appears closer to the surface than it actually is.
Explain reflection, refraction, and diffraction of sound and light.
Reflection - The returning of a wave to the medium from which it came when it hits a barrier. Refraction - The bending of waves due to a change in the medium. Diffraction - Any bending of light by means other than reflection and refraction.
Give examples of constructive and destructive interference.
An intriguing property of all waves is interference?the combined effect of two or more waves overlapping. Consider transverse waves: When the crest of one wave overlaps the crest of another, their individual effects add together. The result is a wave of increased amplitude. This is constructive interference. When the crest of one wave overlaps the trough of another, their individual effects are reduced. The high part of one wave simply fills in the low part of another. This is destructive interference.
Describe how the Doppler Effect explains the change in pitch of a fire-engine siren and the movement of a galaxy.
The Doppler Effect is evident when you hear the changing pitch of an ambulance or fire-engine siren. When the siren is approaching you, the crests of the sound waves encounter your ear more frequently, and the pitch is higher than normal. And when the siren passes you and moves away, the crests of the waves encounter your ear less frequently, and you hear a drop in pitch. The Doppler Effect also occurs for light waves. When a light source approaches, there is an increase in its measured frequency; when it recedes, there is a decrease in its frequency. Galaxies, too, show a red shift in the light they emit. This observation was first made by American astronomer Edwin Hubble. When Hubble observed galaxies through his telescope, he noticed that the colours of the light emitted by their elements seemed to be red-shifted. This implied that the galaxies must be moving away from Earth. Further, Hubble?s observations established that the farther a galaxy is from Earth, the faster it is moving away. This is the basis of our current belief that the universe is ever-expanding.
transfers energy through vibrations. The wave in which the medium vibrates in a direction perpendicular (transverse) to the direction in which the wave travels.
transfers energy through vibrations. The wave in which the medium vibrates in a direction parallel (longitudinal) with the direction in which the wave travels.
Sound, infrasonic, ultrasonic, radio
Hearing any sound occurs because air molecules next to a vibrating object are themselves set into vibration and energy is transferred. These, in turn, vibrate against neighbouring molecules, which, in turn, do the same, and so on. As a result, rhythmic patterns of compressed and rarefied air emanate from the sound source. The resulting vibrating air sets your eardrum into vibration, which, in turn, sends cascades of rhythmic electrical impulses along nerves in the cochlea of your inner ear and into the brain. Thus, when you hear a high-pitched sound, a high-frequency wave from a quickly vibrating source sets your eardrum into fast vibration. Bass guitars, foghorns, and deep-throated bullfrogs vibrate slowly, making low-pitched waves that set your eardrums into slow vibration. Hearing any sound occurs because air molecules next to a vibrating object are themselves set into vibration. These, in turn, vibrate against neighbouring molecules, which, in turn, do the same, and so on. As a result, rhythmic patterns of compressed and rarefied air emanate from the sound source. The resulting vibrating air sets your eardrum into vibration, which, in turn, sends cascades of rhythmic electrical impulses along nerves in the cochlea of your inner ear and into the brain. Thus, when you hear a high-pitched sound, a high-frequency wave from a quickly vibrating source sets your eardrum into fast vibration. Bass guitars, foghorns, and deep-throated bullfrogs vibrate slowly, making low-pitched waves that set your eardrums into slow vibration.
As the ocean waves propagate, their energy is transported. a disturbance that travels from one place to another transporting energy, but not necessarily matter, along with it
Tsunami waves are mechanical waves and thus energy transfer is through the phenomenon of compression and rarefaction. These waves move through their source towards the onshore areas due to the additional impact of wind on the surface of water. This phenomenon of water wave movement can be understood as the generation of ripples on water surface when disturbed by any external impact.
S-waves are transverse?they vibrate the particles of their medium up and down and side-to side, and they travel more slowly than P-waves. S-waves can only travel through solid materials in which where the energy is transferred
Describe how a tsunami transfers energy.
Tsunami transfers energy through the phenomenon of compression and refraction. It is a catastrophic ocean wave, usually caused by a submarine earthquake occurring less than 50 km (30 miles) beneath the seafloor, with a magnitude greater than 6.5 on the Richter scale. Underwater or coastal landslides or volcanic eruptions also may cause a tsunami. A tsunami can have a wavelength in excess of 100 km and period on the order of one hour. Because it has such a long wavelength, a tsunami is a shallow-water wave. Shallow-water waves move with a speed equal to the square root of the product of the acceleration of gravity and the water depth. The rate at which a wave loses its energy is inversely related to its wavelength. A tsunami not only propagates with a high speed, it also can travel a great, transoceanic distance with only limited energy loss. Earthquakes generate tsunamis when the sea floor abruptly deforms and displaces the water above from its equilibrium position. Waves are formed as the displaced water under the influence of gravity attempts to regain its equilibrium. The initial size of a tsunami is determined by the amount of vertical sea floor deformation.
The range of electromagnetic waves that extends infrequency from radio waves to gamma rays. Gamma Rays have frequencies above 1019 Hz, and therefore have energies above 100 keV and wavelength less than 10 picometers
a high-energy electromagnetic radiation that can penetrate solids and ionize gas. It has a wavelength between 0.01 and 10 nanometres, which is between gamma rays and ultraviolet light with a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3 × 1016 Hz to 3 × 1019 Hz) and energies in the range 120 eV to 120 keV.
Ultraviolet (UV) radiation is defined as that portion of the electromagnetic spectrum between x rays and visible light with a wavelength shorter than that of visible light, but longer than xrays, in the range 10 nm to 400 nm, and energies from 3eV to 124 eV
the portion of the invisible electromagnetic spectrum consisting of radiation with wavelengths in the range 750 nm to 1 mm, between light and radio waves and covers the range from roughly 300 GHz (1 mm) to 400 THz (750 nm) with energy range from 1.24meV ? 1.24eV
an electromagnetic wave whose wavelength ranges from 1 mm to 30 cm. Use: radar, radio transmissions, cooking or heating devices with wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz (0.3 GHz) and 300 GHz.
Radio Waves (AM and FM)
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Like all other electromagnetic waves, they travel at the speed of light with frequencies lower than around 300 GHz (or, equivalently, wavelengths longer than about 1 mm) with energy from 12.4feV ? 1.24meV.
This makes up less than a millionth of 1% of the electromagnetic spectrum. The lowest frequency of light we can see with our eyes appears red. The highest visible frequencies, which are nearly twice the frequency of red light, appear violet. Wavelengths are between 380 nm and 760 nm (790?400 terahertz).
How does light act as both a wave and a particle?
We have described light as a wave. The earliest ideas about the nature of light, however, were that light was composed of tiny particles. Evidently, light has both a wave nature and a particle nature?a wave?particle duality. It reveals itself as a wave or particle depending on how it is being observed. Simply stated, light behaves as a stream of photons when it interacts with a sheet of metal or other detector and it behaves as a wave in travelling from a source to the place where it is detected. Light travels as a wave and hits as a stream of photons. The fact that light exhibits both wave and particle behaviour is one of the most interesting surprises that physicists discovered in the twentieth century.
What is an electromagnetic wave?
Are the mechanism by which electromagnetic energy (electromagnetic radiation) moves. They are composed of two components: an electric wave, or an electric field, and a magnetic wave or magnetic field.
How are all electromagnetic waves the same? How do they differ?
The electromagnetic spectrum is a continuous range of electromagnetic waves extending from radio waves to gamma rays. The descriptive names of the sections are merely a historical classification, for all the waves are the same in nature, differing principally in frequency and wavelength; all travel at the same speed.
Describe the general structure of an atom.
The atom is a basic unit of matter consisting of a dense, central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons (except in the case of hydrogen-1, which is the only stable nuclide with no neutrons). The electrons of an atom are bound to the nucleus by the electromagnetic force. Likewise, a group of atoms can remain bound to each other, forming a molecule. An atom containing an equal number of protons and electrons is electrically neutral; otherwise it has a positive or negative charge and is an ion. An atom is classified according to the number of protons and neutrons in its nucleus: the number of protons determines the chemical element, and the number of neutrons determines the isotope of the element.
What makes an atom radioactive?
Atoms with unstable nuclei are said to be radioactive. Sooner or later, they break down and eject energetic particles and emit electromagnetic radiation.
Explain the difference between an alpha particle, a beta particle, and a gamma ray.
An alpha particle is the combination of two protons and two neutrons (in other words, it is the nucleus of the helium atom, atomic number 2). Alpha particles are relatively easy to shield against because of their relatively large size and their double positive charge (+2) whileW A beta particle is an electron ejected from a nucleus. Once ejected, it is indistinguishable from an electron in a cathode ray or in an electrical circuit, or from an electron orbiting the atomic nucleus. The difference is that a beta particle originates inside the nucleus?from a neutron. As we shall soon see, the neutron becomes a proton once it loses the electron that has become a beta particle. A beta particle is normally faster than an alpha particle, and it carries only a single negative charge (-1 ) and Gamma rays are the high-frequency electromagnetic radiation emitted by radioactive elements. Like photons of visible light, a gamma ray is pure energy. The amount of energy in a gamma ray, however, is much greater per photon than in visible light, ultraviolet light, or even X-rays. Because they have no mass or electric charge, and because of their high energies, gamma rays are able to penetrate through most materials.
List sources of radiation.
Cosmic radiation, Ground , Air (radon-222), Human tissues (K-40; Ra-226), Smoking , Medical procedures, Diagnostic X rays , Nuclear medicine , TV tubes, other consumer products , Weapons-test fallout , Coal-burning power plants, Commercial nuclear power plants
What is the difference between a rad (radiation absorbed dose) and a rem (roentgen equivalent mass)?
Radiation dosage is commonly measured in rads (radiation absorbed dose), a unit of absorbed energy. One rad is equal to 0.01 joule of radiant energy absorbed per kilogram of tissue while rem is a unit of measurement for radiation dosage based on potential damage
Explain the strong nuclear force and the electric force in an atom.
Strong nuclear force in an atom is an attraction of positively charged protons in the nucleus that remain clumped together. It acts between all nucleons. This force is very strong, but only over extremely short distances (about 10?15 meters, the diameter of a typical atomic nucleus). While Repulsive electrical interactions (electric force), on the other hand, have a relatively long range.
Why must the strong nuclear force be present in the nucleus of an atom?
While two protons repel each other by the electric force, they also attract each other by the strong nuclear force. Both of these forces act simultaneously. So long as the attractive strong nuclear force is stronger than the repulsive electric force, the protons will remain together. Under conditions in which the electric force overcomes the strong nuclear force, however, the protons fly apart from each other. Neutrons serve as?nuclear cement? holding the atomic nucleus together. Protons attract both protons and neutrons by the strong nuclear force.
How does the size of an atom affect the strength of the strong nuclear force and the electric force?
A large nucleus is not as stable as a small one. In a helium nucleus, for example, each of the two protons feels the repulsive effect of the other. In a uranium nucleus, each proton feels the repulsive effects of the other 91 protons! The nucleus is unstable. We see that there is a limit to the size of the atomic nucleus. It is for this reason that all nuclei having more than 82 protons are radioactive. For large nuclei, more neutrons than protons are needed. Because the strong nuclear force diminishes rapidly over distance, nucleons must be practically touching in order for the strong nuclear force to be effective. Nucleons on opposite sides of a large atomic nucleus are not attracted to one another. The electric force, however, diminishes very little across the diameter of a large nucleus, and so it wins out over the strong nuclear force. To compensate for the near absence of the strong nuclear 24 force across the diameter of the nucleus, large nuclei have more neutrons than protons.
What happens during nuclear fission?
In the nucleus of every atom, there exists a delicate balance between attractive nuclear forces and repulsive electric forces between protons. In all known nuclei, the nuclear forces dominate. In uranium, however, this domination is tenuous. If a uranium nucleus stretches into an elongated shape (Figure 10.19), the electrical frces may push it into an even more elongated shape. If the elongation passes a certain point, electrical forces overwhelm strong nuclear forces and the nucleus splits.
Why is a critical mass of radioactive material necessary for a large explosion?
This is because of geometry: The ratio of surface area to mass is larger in a small piece than in a large one (just as there is more skin on six small potatoes having a combined mass of 1 kilogram than there is on a single 1-kilogram potato). So there is more surface area on a bunch of small pieces of uranium than on a large piece. In a small piece of U-235, neutrons leak through the surface before an explosion can occur. In a bigger piece, the chain reaction builds up to enormous energies before the neutrons reach the surface and escape (Figure 10.21). For masses greater than a certain amount, called the critical mass, an explosion of enormous magnitude may occur.
Explain the meaning of the equation E=mc2.
E stands for the energy that any mass has at rest, m stands for mass, and c is the speed of light. The quantity is the proportionality constant of energy and mass. This relationship between energy and mass is the key to understanding why and how energy is released in nuclear reactions. The more energy associated with a particle, the greater the mass of the particle.
What happens to the mass per nucleon in uranium when it is split into smaller nuclei?
Energy is released when a uranium nucleus splits into two nuclei of lower atomic number. Uranium have a relatively large amount of mass per nucleon. When the uranium nucleus splits in half, however, smaller nuclei of lower atomic numbers are formed. Uranium have a smaller amount of mass per nucleon. Thus, nucleons lose mass in their transition from being in a uranium nucleus to being in one of its fragments. When this decrease in mass is multiplied by the speed of light squared ( in Einstein?s equation), the product is equal to the energy yielded by each uranium nucleus as it undergoes fission.
Describe the process of nuclear fusion.
Energy is gained as light nuclei combine. This combining of nuclei is nuclear fusion?the opposite of nuclear fission when two small nuclei fuse?say, a pair of hydrogen isotopes?the mass of the resulting helium nucleus is less than the mass of the two small nuclei before fusion. Energy is released as smaller nuclei fuse. For a fusion reaction to occur, the nuclei must collide at a very high speed in order to overcome their mutual electric repulsion. The required speeds correspond to the extremely high temperatures found in the Sun and other stars. Fusion brought about by high temperatures is called thermonuclear fusion. In the high temperatures of the Sun approximately 657 million tons of hydrogen is converted into 653 million tons of helium each second. The missing 4 million tons of mass is converted to energy?a tiny bit of which reaches Planet Earth as sunshine. Such reactions are, 25 quite literally, nuclear burning. Thermonuclear fusion is analogous to ordinary chemical combustion. In both chemical and nuclear burning, a high temperature starts the reaction; the release of energy by the reaction maintains a high enough temperature to spread the fire. The net result of the chemical reaction is a combination of atoms into more tightly bound molecules. In nuclear fusion reactions, the net result is more tightly bound nuclei. In both cases, mass decreases as energy is released.
How does the mass per nucleon change in nuclear fusion?
As we move along the list of elements from hydrogen to iron, the average mass per nucleon decreases. Thus, when two small nuclei fuse?say, a pair of hydrogen isotopes?the mass of the resulting helium nucleus is less than the mass of the two small nuclei before fusion. Energy is released as smaller nuclei fuse
Tracers can be used to measure the speed of chemical processes and to track the movement of a substance through a natural system such as a cell or a tissue. In medicine tracers are applied, such as Technetium-99 in autoradiography and nuclear medicine, including single photon emission computed tomography (SPECT), positron emission tomography (PET) and scintigraphy. It has a basic isotope requirement during its isotopic reactions
isotopic dating and radiometric dating:
is a technique used to date materials such as rocks , usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates. It is the principal source of information about the absolute age of rocks and other geological features, including the age of the Earth itself, and can be used to date a wide range of natural and man-made materials. Together with stratigraphic principles, radiometric dating methods are used in geochronology to establish the geological time scale. Among the best-known techniques are radiocarbon dating, potassium-argon dating and uranium-lead dating. By allowing the establishment of geological timescales, it provides a significant source of information about the ages of fossils and the deduced rates of evolutionary change. Radiometric dating is also used to date archaeological materials, including ancient artefacts. Different methods of radiometric dating vary in the timescale over which they are accurate and the materials to which they can be applied.
Geiger counters are used to detect ionizing radiation (usually beta particles and gamma rays, but certain models can detect alpha particles) Some Geiger counters can be used to detect gamma radiation as general purpose alpha/beta/gamma portable contamination and dose rate instruments etc..
Radiotherapy is used for the treatment of malignant cancer, and may used as a primary or adjuvant modality. It is also common to combine radiotherapy with surgery, chemotherapy, hormone therapy or some mixture of the three. Most common cancer types can be treated with radiotherapy in some way. The precise treatment intent (curative, adjuvant, neoadjuvant, therapeutic, or palliative) will depend on the tumor type, location, and stage, as well as the general health of the patient
Smoke Detectors and Americium-241
How many of us have smoke detectors in our house? Chances are that a great number of homes have had one or more of these devices installed as an early warning system in case of fire. What most consumers don't know is that many of these units contain a small amount of americium-241. By utilizing the radioactive properties of this material, smoke from afire can be detected at a very early stage. This early warning capability has saved many lives.
is a method of treating food in order to make it safer to eat and have a longer shelf life. This process is not very different from other treatments such as pesticide application, canning, freezing and drying. The end result is that the growth of disease-causing microorganisms or those that cause spoilage are slowed or are eliminated altogether. This makes food safer and also keeps it fresh longer.Food irradiated by exposing it to the gamma rays of a radioisotope -- one that is widely used is cobalt-60. The energy from the gamma ray passing through the food is enough to destroy many disease-causing bacteria as well as those that cause food to spoil, but is not strong enough to change the quality, flavor or texture of the food. It is important to keep in mind that the food never comes in contact with the radioisotope and is never at risk of becoming radioactive.
What happens during the thermonuclear fusion reaction in the Sun?
Fusion brought about by high temperatures, as occurs in the Sun, is called thermonuclear fusion. All fusion reactions release energy because the total mass of reactants is greater than the total mass of the products. The mass ?lost? in the reaction is converted to energy in accordance with Einstein?s famous equation, the mass-energy equivalence: . Each thermonuclear fusion reaction in the Sun causes four hydrogen nuclei to fuse together to form one helium nucleus. The resulting helium has 99.3 percent of the original hydrogen mass. The difference in mass is converted to energy, which transfers away from the core in the form of X rays and gamma rays. At the surface, much is emitted as light, a tiny bit of which nicely reaches Planet Earth.
When does the thermonuclear fusion reaction start?
In the radiation zone, atoms absorb and reradiate electromagnetic energy generated in the core, moving it toward the Sun?s surface and start the thermonuclear fusion. The process is slow, taking perhaps a million years, because the X rays and gamma rays from the core undergo countless collisions with atoms as they trace an indirect route through the radiation zone. The convection zone is a turbulent layer consisting of low-density gases that are stirred by convection, a mode of heat transfer. At the bottom of the convection zone, atoms of gas are heated by radiation from the radiation zone. As the gases warm and become less dense, they rise to the Sun?s surface. The gases emit energy into space from the surface in the form of visible light, ultraviolet light, and infrared radiation. The atoms of gas in the convection zone, having lost some of their energy as radiation, lose volume, become denser, and sink back to the radiation zone. There, they become heated again as they absorb radiation from the Sun?s core. The heated gas atoms rise again, carrying energy from the bottom to the top of the convection zone, then losing it at the surface by radiation, and sinking again.
Describe the difference between hydrogen-burning and helium-burning in stars.
a star?s hydrogen-burning lifetime lasts for a period of a few million to 50 billion years, depending on its mass. High-mass stars are more luminous than low-mass stars, meaning that they burn their hydrogen fusion fuel at a faster rate. Massive stars must be more luminous than small-mass stars so that the outward pressure of their nuclear fusion can offset the greater gravitational force of their contraction. Massive stars start out with more hydrogen fuel than small-mass stars, but they consume their fuel so much faster that they die billions of years younger than smaller stars. No star lasts forever. In the old age of an average-mass star like our Sun, the supply of hydrogen fuel is diminished so gravity overwhelms thermal pressure and the star pulls inward. As the burned-out hydrogen core contracts due to gravity, its temperature rises. At a certain point, the temperature becomes high enough in the core to launch helium burning?the fusion of helium to carbon. The star then has a structure consisting of concentric shells. Helium fuses to carbon at the star?s center while hydrogen fuses to helium in a surrounding shell. Energy output soars, moving the star off the main sequence.
What is the general chemical composition of stars?
About three-fourths of the interstellar material from which any star forms is hydrogen; one-fourth is helium; and no more than 2 percent of the material from which a star forms consists of heavier chemical elements.
Explain how stars can differ in brightness and color.
Brightness relates to how much energy a star is producing, while its color indicates its surface temperature.
What is the Hertzsprung-Russell (H-R) diagram?
The H?R diagram is a plot of the luminosity versus surface temperature of stars. Luminous stars are near the top of the diagram, and dim stars toward the bottom. Hot bluish stars are toward the left side of the diagram and cool reddish stars are toward the right side.
Explain the difference in the following types of stars: main sequence stars, red giants, and white dwarfs.
Stars on the main sequence, including our Sun, generate energy by fusing hydrogen to helium. As we would expect, the hottest main sequence stars are the brightest and bluest stars and the coolest main-sequence stars are the most dim While Red giants stars do not follow the pattern of the hydrogen-burning they are very bright. The fact that the red giants are both much cooler and much brighter than the Sun tells us that these stars must also be much larger than the Sun and White dwarfs stars are so dim they cannot be seen with the unaided eye. The surfaces of these stars can be hotter than the Sun, White dwarfs are typically the size of Planet Earth or even smaller, yet they have mass comparable to the Sun. The density (or mass per volume) of a white dwarf is thus extremely high?higher than anything found on Earth.
A protostar is the birth of a star. They are stars that are starting out in their life as a star. They don?t get very warm, and are pretty cool for a star?s temperature.
a star?s hydrogen-burning lifetime lasts for a period of a few million to 50 billion years, depending on its mass. More massive stars have shorter lives than less massive stars.
Helium fuses to carbon at the star?s center while hydrogen fuses to helium in a surrounding shell. Energy output soars, moving the star off the main sequence.
are stars that have entered one of the late phases in stellar evolution. After being in the main sequence for billions of years, red giants used up
the rapid implosion of a star under its own gravitational forces that occurs when the internal temperature drops sufficiently
a small, dim, extremely dense star that has collapsed on itself and is in the final stages of its evolution.
An event wherein a white dwarf suddenly brightens and appears as a ?new? star/ The explosion of a massive star caused by gravitational collapse with the emission of enormous quantities of matter.
A small, extremely dense star composed of tightly packed neutrons formed by the welding of protons and electrons.
The remains of a giant star that has collapsed upon itself, so dense, and with a gravitational field so intense, that light itself cannot escape from it.
What components make up our solar system?
The solar system is the collection of objects gravitationally bound to our Sun. In addition to the Sun itself, the solar system contains at least nine planets, their approximately 150 moons, a large number of asteroids (small, rocky bodies), and comets (small, icy bodies). These objects exist in the interplanetary medium, a sparse blend of dust and gas particles.
Describe how the solar system is organized.
The Sun is at the center of the solar system and contains most of its mass?a whopping 99.86 percent. Moving outward from the Sun are, in order, the inner planets: Mercury, Venus, Earth, and Mars. Next is the main asteroid belt, which lies between the orbits of Mars and Jupiter. Then, there are the outer planets: Jupiter, Saturn, Uranus, Neptune, and, as we shall see, controversial Pluto. Beyond Neptune, containing Pluto, lies the disk shaped Kuiper Belt (pronounced ?koy-per?) of comets and assorted objects. Far beyond the Kuiper Belt is the Oort Cloud (rhymes with short), a giant cometary sphere completely surrounding the solar system.
Draw a diagram that shows the location of the various components that make up the solar system.
location of the various components that make up the solar system.
Sun, Mercury, Venus, Earth, Moon, Mars, Jupiter, Saturn, & Uranus
Describe the structure of the sun.
The Sun is at the center of the solar system and contains most of its mass?a whopping 99.86 percent.
Explain the orbits and rotations of the planets.
The planets exhibit a high degree of orderliness in their motions and in their positioning. For example, all the planets travel in elliptical orbits around the Sun. And except for Pluto, all the planets and their larger moons follow orbits that lie roughly in the same plane. This plane, called the ecliptic, is defined as the plane of Earth?s orbit. Further, all the planets and almost all of their moons orbit in the same direction?counterclockwise (when viewed from the Sun?s north pole). This is also the direction in which the Sun and almost all of the planets and their moons spin or rotate. Also, the planets are neatly divided such that the inner planets are small, solid, and rocky while the outer planets are large and gaseous.
How are the terrestrial planets different than the Jovian planets?
The inner planets?Mercury, Venus, Earth, and Mars?are solid and relatively small and dense. For this reason they are often called the ?terrestrial planets.? The outer planets are large, have many rings and satellites, and are composed primarily of hydrogen and helium gas. The outer planets are often referred to as the ?Jovian planets? because they resemble Jupiter in terms of their large sizes and gaseous compositions.
Explain the big bang theory.
The study of the universe in its totality, and especially its origin and structure, is called cosmology. The cornerstone of modern cosmology is the theory of the Big Bang, the idea that the physical universe began in a primordial explosion 13.7 billion years ago. The Big Bang marks the beginning of both space and time for our universe. Since its violent beginning, cosmologists argue, the universe has developed in a steady progression of physical processes governed by physical laws. Evidence that the universe began as a primordial explosion?the Big Bang?is the expansion of the universe. It is thought that, at the start, all space existed as one point that contained all the matter that exists today. Since the Big Bang, the Universe has continued to expand outward from this point. The present expansion of the universe is evident in a Doppler red shift in the ligh that we receive from galaxies. The Big Bang theory developed from observations of the structure of the Universe and from theoretical considerations. It is the prevailing cosmological theory of the early development of the universe. Cosmologists use the term Big Bang to refer to the idea that the universe was originally extremely hot and dense at some finite time in the past and has since cooled by expanding to the present diluted state and continues to expand today. The theory is supported by the most comprehensive and accurate explanations from current scientific evidence and observation.
the law holding that the speed at which distant galaxies are moving away from Earth is proportional to their distance from the observer. In 1929, Edwin Hubble announced that almost all galaxies appeared to be moving away from us. This phenomenon was observed as a redshift of a galaxy's spectrum. This redshift appeared to have a larger displacement for faint, presumably further, galaxies. Hence, the farther a galaxy, the faster it is receding from Earth.
cosmic background radiation
no matter which way they directed their receiver, they detected microwaves with a wavelength of 7.35 cm coming toward Earth. Arno and Penzias were puzzled?with no specific source of the radiation, where were the microwaves coming from and why? Remember that any object above absolute zero emits energy in the form of electromagnetic radiation. The frequency (wavelength) of this radiation is proportional to the absolute temperature of the emitter. Theorists at Princeton, working around the same time as Scientists showed that if the universe began in a primordial explosion as described by the Big Bang, it would still be cooling off. Further, they showed that the universe would have cooled by today to an average temperature of 2.7 K. A universe of this temperature would be expected to emit microwave radiation of just the frequency observed by Penzias and Wilson. Thus the influx of microwave radiation that initially puzzled Penzias and Wilson was found to be emitted by the cooling universe itself. This faint microwave radiation is now referred to as cosmic background radiation and is taken as strong evidence of the Big Bang.
Doppler red shift
Is an extremely large and unprecedented redshift, which indicated enormous recessional velocities?some of these objects were receding at more than 90 percent the speed of light. Clearly, the objects couldn?t be stars in our own galaxy, because we would have noticed a change in their positions against the background of the fixed stars.
More evidence for the Big Bang is provided by measurements of different elements in the universe. The universe is found to contain about 74 percent hydrogen and 26 percent helium by mass, the two lightest elements. All the other heavier elements, including elements common on Earth such as carbon and oxygen, make up just a tiny trace of all matter. Calculations show that these abundances could only have been made in a universe that began in a very hot sea of radiation and elementary particles.
is a scatter graph of stars showing the relationship between the stars' absolute magnitudes or luminosity versus their spectral types or classifications and effective temperatures. Hertzprung-Russell diagrams are not pictures or maps of the locations of the stars. Rather, they plot each star on a graph measuring the star's absolute magnitude or brightness against its temperature and color. A plot of intrinsic brightness versus surface temperature for stars. When so plotted, stars? positions take the form of a main sequence for average stars, with exotic stars above or below the main sequence.
An optical telescope is a telescope which is used to gather and focus light mainly from the visible part of the electromagnetic spectrum for directly viewing a magnified image for making a photograph, or collecting data through electronic image sensors.
Hubble space telescope:
The Hubble Space Telescope (HST) is a space telescope that was first carried into orbit by a space shuttle in 1990. A telescope mounted on a satellite that orbits the Earth, used to observe distant parts of the universe and photograph them. Although not the first space telescope, Hubble is one of the largest and most versatile, and is well-known as both a vital research tool and a public relations boon for astronomy.
Very Large Array telescope:
The Very Large Array is a Y-shaped collection of 27 individual radio dishes that can be moved close together or far apart. The resolution of the array depends on whether the dishes are positioned near each other or spread out. The amount of light the array can collect, however, depends on the size and number of dishes, not on the space between the dishes.
(XRT) is a high resolution grazing incidence telescope, which is a successor to the highly successful Yohkoh. A primary purpose of the Solar-B is to observe the generation, transport, and emergence of solar magnetic fields, and ultimate dissipation of magnetic energy in a form such as flares and pico-flares, coronal heating, coronal mass ejection. The XRT aboard Solar-B observes the dissipation part of the life-cycle story of solar magnetic fields. High-resolution soft X-ray images would reveal magnetic field configuration and its evolution, allowing us to observe the energy buildup, storage and release process in the corona for any transient event.
A radio telescope is a form of directional radio antenna used in radio astronomy. The same types of antennas are also used in tracking and collecting data from satellites and space probes.
A telescope, similar in operation to an optical telescope that is designed to detect infrared radiation. Because infrared radiation is emitted by warm objects, infrared telescopes need to be shielded from local heat sources, as by chilling them with liquid nitrogen or locating them in polar regions. Many are placed on high mountains or are mounted on balloons or satellites in order to place them above the lower atmosphere, where water vapor absorbs much of the incoming infrared radiation.
Gamma ray telescope:
Is a device for detecting and determining the directions of extraterrestrial gamma rays, using coincidence or anticoincidence circuits with scintillation or semiconductor detectors to obtain directional discrimination.
an instrument for dispersing light, usually light in the visible range, into a spectrum in order to measure it
A spectral line is a dark or bright line present in a uniform and continuous electromagnetic spectrum. The spectral lines result from the interaction between a quantum system (generally atoms, but sometimes also molecules or atomic nuclei) and electromagnetic radiation. A discrete band of light in a spectrum associated with a specific wavelength and used to identify substances. Characteristic spectral lines are emitted by atoms and molecules and may be used to identify substances.
General theory of relativity:
General relativity is a theory of gravitation developed by Einstein in the years 1907?1915. The development of general relativity began with the equivalence principle, under which the states of accelerated motion and being at rest in a gravitational field (for example when standing on the surface of the Earth) are physically identical. The upshot of this is that free fall is inertial motion; an object in free fall is falling because that is how objects move when there is no force being exerted on them, instead of this being due to the force of gravity as is the case in classical mechanics. This is incompatible with classical mechanics and special relativity because in those theories inertially moving objects cannot accelerate with respect to each other, but objects in free fall do so. To resolve this difficulty Einstein first proposed that spacetime is curved. In 1915, he devised the Einstein field equations which relate the curvature of spacetime with the mass, energy, and momentum within it.
the portion of the invisible electromagnetic spectrum consisting of radiation with wavelengths in the range 750 nm to 1 mm, between light and radio waves.
the branch of physics in which the structure, forces, and behavior of the atomic nucleus are studied
a device that uses a lens or system of lenses to produce a greatly magnified image of an object.
an instrument that separates atoms and molecules according to their mass and that records the resulting mass spectrum
is the application of physics to the study of the atmosphere. Atmospheric physicists attempt to model Earth's atmosphere and the atmospheres of the other planets using fluid flow equations, chemical models, radiation balancing, and energy transfer processes in the atmosphere.
Motion, like temperature, also shifts frequency. You hear this all the time with the sound of a passing car, going eeeeeeyyyyoooom. Objects moving toward you have a higher pitch than the same object moving away. The same thing applies in space. Light from stars moving toward us -- and all the "notes" or elements in that stellar orchestra -- gets shifted to higher energies. Through spectroscopy, scientists study the contents and temperature of a celestial symphony in motion.
the study of quantity, structure, space, and change. Mathematicians seek out patterns, formulate new conjectures, and establish truth by rigorous deduction from appropriately chosen axioms and definitions
a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines. Among the most important topics are five unifying principles that can be said to be the fundamental axioms of modern biology
the science of matter and the changes it undergoes. The science of matter is also addressed by physics, but while physics takes a more general and fundamental approach, chemistry is more specialized, being concerned with the composition, behavior, structure, and properties of matter, as well as the changes it undergoes during chemical reactions. It is a physical science which studies various substances, atoms, molecules, crystals and other aggregates of matter whether in isolation or combination, and which incorporates the concepts of energy and entropy in relation to the spontaneity of chemical processes.
Heisenberg?s Uncertainty Principle is one of the fundamental concepts of Quantum Physics, and is the basis for the initial realization of fundamental uncertainties in the ability of an experimenter to measure more than one quantum variable at a time. Attempting to measure an elementary particle?s position to the highest degree of accuracy, for example, leads to an increasing uncertainty in being able to measure the particle?s momentum to an equally high degree of accuracy.
an equation used to estimate the number of detectable extraterrestrial civilizations in the Milky Way galaxy. It is used in the fields of exobiology and the search for extraterrestrial intelligence (SETI). The equation was devised by Frank Drake in 1961. N=R x Fp x Ne x Fl x Fi x Fc x L Where: R= the number of suitable stars?stars like the Sun?that form in our galaxy per year. Fp =The fraction of these stars that have planets. Ne =The number of Earth-like planets?meaning planets that have liquid water? within each planetary system. Fl = The fraction of Earth-like planets where life develops. Fi = The fraction of life sites where intelligent life develops. Fc =The fraction of intelligent life sites where communication develops. L= The ?lifetime? (in years) of a communicative civilization. N= The number of civilizations with which we could possibly communicate.
the angle between two imaginary lines from two different observation points meeting at an astronomical object, used to measure the object's distance from Earth.
What are elements?
Any material that is made up of only one type of atom. Any substance that cannot be broken down into a simpler-one by a chemical reaction. Elements consist of atoms with the same number of protons in their nuclei, and 92 occur naturally on Earth.
Describe the location and charge of the subatomic particles that make up an atom.
Protons, neutrons and electrons. Protons have a relative mass of 1 and a charge of +1, they are found in the nucleus of an atom. Neutrons have a relative mass of 1 and no charge, they are also found in the nucleus. Electrons have a relative mass of 1/1836 and a charge of -1. They are found in specific orbits around the nucleus and are held in these orbits by the positive charge of the protons in the nucleus.
Why are atoms electrically neutral?
So the opposite charges of protons and electrons balance each other, producing a zero net charge. The atom is electrically neutral. For example, an electrically balanced oxygen atom has a total of eight electrons and eight protons.
the number of protons each atom of a given element contains and its isotopes, used to determine that element's position in the periodic table.
is the mass of an atom, most often expressed in unified atomic mass units. The atomic mass may be considered to be the total mass of protons, neutrons and electrons in a single atom (when the atom is motionless).
atomic mass unit (amu):
a unit used to express the masses of atoms and molecules, equal to one-twelfth of the mass of a carbon-12 atom or about 1.660 x 10-27 kg. Symbol u
How do the three isotopes of hydrogen (hydrogen-1, hydrogen-2, and hydrogen-3) differ?
a hydrogen isotope with only one proton is called hydrogen-1, where 1 is the mass number. A hydrogen isotope with one proton and one neutron is therefore hydrogen-2, and a hydrogen isotope with one proton and two neutrons is hydrogen-3. The three isotopes of hydrogen differ in the number of its neutron. They have the same number of proton but differs in the number of neutron and therefore, different mass number. And also hydrogen-1 is called protium, hydrogen-2 is called deuterium, and hydrogen-3 is called tritium.
Compare the mass, atomic number, electrical charge, and neutron number or isotopes of iron (iron-55 and iron-56).
Iron-55 - Mass - 55 - Atmotic Mass -Electrical Charge -- Neutron Number - 29 - Iron-56 Mass 56 - Atomic Number 26 - Electrical charge- - Neutron number 30
Explain the shell model of the atom.
According to the shell model, electrons behave as if they are arranged in a series of concentric shells. A shell is defined as a region of space about the atomic nucleus within which electrons may reside. An important aspect of this model is that there are at least seven shells and that each shell can hold only a limited number of electrons.The innermost shell can hold two; the second and third shells, eight electrons each; the fourth and fifth shells, 18 each; and the sixth and seventh shells, 32 each.
What are valence electrons?
In the shell model of an atom, electrons behave as if they are arranged in a series of concentric shells. Wherein the shell is defined as a region of space about the atomic nucleus within which electrons may reside. An important aspect of this model is that there are at least seven shells and that each shell can hold only a limited number of electrons.
How can the number of valence electrons for a given element be determined using the periodic table?
In using the periodic table, to predict the number of valence electrons in an atom works reasonably well for the metals, metalloids and nonmetals. However, with the transition metals quantum theory is needed to explain behavior. In determining Metals, metalloids and nonmetals number of valence electrons in an atom, the transition metals should be ignored and count from left to right in group A of the Periodic Table. Thus, elements in group IA have 1 valence electron, elements in group IIA have 2, IIIA have 3 valence electrons, etc.
Elements Group 1 (IA,IA):
valence electron is 1. the alkali metals or lithium family- The alkali metals are a series of chemical elements forming Group 1 of the periodic table: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). (Hydrogen, although nominally also a member of Group 1, very rarely exhibits behavior comparable to the alkali metals). The alkali metals provide one of the best examples of group trends in properties in the periodic table, with well characterized homologous behavior down the group.
Elements Group 2 (IIA,IIA):
valence electron is 2. the alkaline earth metals or beryllium family- The alkaline earth metals are a series of elements comprising Group 2 (IUPAC style) (Group IIA) of the periodic table: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra). This specific group in the periodic table owes its name to their oxides that simply give basic alkaline solutions. These elements melt at such high temperature that they remain solids (?earths?) in fires. The alkaline earth metals provide a good example of group trends in properties in the periodic table, with wellcharacterized homologous behavior down the group. With the exception of Be and Mg, the metals have a distinguishable flame color, brick-red for Ca, magenta-red for Sr, green for Ba and crimson red for Ra.
Elements Group 3 (IIIA,IIIB):
the scandium family up to Group 12- The general method for counting valence electrons is generally not useful for transition metals. Instead the modified d electron count method is used. generally hard metals with low aqueous solubility, and have low availability to the biosphere. No group 3 has any documented biological role in living organisms. The radioactivity of the actinides generally makes them highly toxic to living cells.
Elements Group 4 (IVA,IVB):
the titanium family- elements that occur naturally are titanium (Ti), zirconium (Zr) and hafnium (Hf). The first three members of the group share similar properties; all three are hard refractory metals under standard conditions. However the fourth element rutherfordium (Rf), has been synthesized in the laboratory, none of them have been found occurring in nature. All isotopes of rutherfordium are radioactive.
Elements Group 5 (VA,VB):
the vanadium family- is one in the series of elements in group 5 in the periodic table, which consists of vanadium (V), niobium (Nb), tantalum (Ta), and dubnium (Db). Like other groups, the members of this family show patterns in its electron configuration, especially the outermost shells.
Elements Group 6 (VIA,VIB):
the chromium family- is one in the series of elements in group 6 (IUPAC style) in the periodic table, which consists of the transition metals chromium (Cr), molybdenum (Mo), tungsten (W), and seaborgium (Sg). Like other groups, the members of this family show patterns in its electron configuration, especially the outermost shells resulting in trends in chemical behavior:
Elements Group 7 (VIIA,VIIB):
the manganese family- is one in the series of elements in group 7 (IUPAC style) in the periodic table, which consists of the transition metals manganese (Mn), technetium (Tc), rhenium (Re), and bohrium (Bh). Like other groups, the members of this family show patterns in its electron configuration, especially the outermost shells resulting in trends in chemical behavior: Two of the four members, technetium and bohrium, are radioactive with short enough half life that they are not present in nature. Furthermore rhenium is a rare element which occurs only in traces in other mineral. These facts make manganese the only abundant element of the group. This is also shown in difference in the annual world production. In 2007 11 million metric tons of manganese was mined while in the same year the world production of rhenium was between 40 and 50 metric tons. They are also very reactive.
Elements Group 8 (VIII, VIIIB):
the iron family- is one in the series of elements in group 8 (IUPAC style) in the periodic table, which consists of the transition metals iron (Fe), ruthenium (Ru), osmium (Os) and hassium (Hs). Like other groups, the members of this family show patterns in its electron configuration, especially the outermost shells though ruthenium curiously does not follow the trend: All of these elements are classed in Group 8 because their valence shells hold eight electrons. Hassium can only be produced in the laboratory and has not been found in nature.
Elements Group 9 (VIII, VIIIB):
the cobalt family- contains the elements cobalt (Co), rhodium (Rh), iridium (Ir), and meitnerium (Mt). These are all d-block transition metals. All known isotopes of Mt are radioactive with short half-lives, and it is not known to occur in nature; only minute quantities have been synthesized in laboratories. Like other groups, the members of this family show patterns in its electron configuration, especially the outermost shells resulting in trends in chemical behavior, though rhodium curiously does not follow the pattern:
Elements Group 10 (VIII, VIIIB):
the nickel family- is one in the series of elements in group 10 (IUPAC style) in the periodic table, which consists of the transition metals nickel (Ni), palladium (Pd), platinum (Pt), and darmstadtium (Ds). Like other groups, the members of this family show patterns in its electron configuration, especially the outermost shells.
Elements Group 11 (IB,IB):
the coinage metals (not an IUPAC-recommended name) or copper family- is one in the series of elements in group 11 in the periodic table, consisting of transition metals which are the traditional coinage metals of copper (Cu), silver (Ag), and gold (Au). Roentgenium (Rg) belongs to this group of elements based on its electronic configuration, but cannot be considered coinage metal (short lived transactinide with a 3.6 seconds half-life). The name "coinage metals" should not be used as an alternative name for Group 11 elements, as various cultures have used other metals in coinage including aluminum, lead, nickel, stainless steel, and zinc). Also, Group 11 includes roentgenium, which is unable to be used as coinage due to its radioactivity. The term 'coinage metal' is not recognized by the International Union of Pure and Applied Chemistry (IUPAC) as a designator for group 11 elements.
Elements Group 12 (IIB,IIB):
the zinc family- elements in group 12 in the periodic table, consisting of zinc (Zn), cadmium (Cd) and mercury (Hg). The inclusion of copernicium (Cn) in group 12 is supported by recent experiments on individual Cn atoms. All elements in this group are metals.
Elements Group 13 (IIIB,IIIA):
valence electron is 3 the boron family- The boron group consists of boron (B), aluminium (Al), gallium (Ga), indium (In), thallium (Tl), and ununtrium (Uut).Like other groups, the members of this family show patterns in its electron configuration, especially the outermost shells resulting in trends in chemical behaviour. The group has previously also been referred to as the earth metals and the triels, from the Latin tri, three, stemming from the naming convention of this group as Group IIIB. These elements are characterized by having three electrons in their outer energy levels (valence layers). Boron is considered a metalloid, and the rest are considered metals of the poor metals groups. Boron occurs sparsely probably because of disruption of its nucleus by bombardment with subatomic particles produced from natural radioactivity. Aluminium occurs widely on earth and in fact, it is the third most abundant element in the Earth's crust (7.4%).
Elements Group 14 (IVB,IVA):
valence electron is 4 the carbon family- is a periodic table group consisting of carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), and ununquadium (Uuq). The group was once also known as the tetrels (from Greek tetra, four), stemming from the Roman numeral IV in the group names, or (not coincidentally) from the fact that these elements have four valence electrons (see below). Like other groups, the members of this family show patterns in its electron configuration, especially the outermost shells resulting in trends in chemical behaviour.
Elements Group 15 (VB,VA):
valence electron is 5 the pnictogens or nitrogen family- is a periodic table group consisting of nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi) and ununpentium (Uup). It is also collectively named the pnictogens. The "five" ("V") in the historical names comes from the fact that these elements have five valence electrons. Like other groups, the members of this family show patterns in its electron configuration, especially the outermost shells resulting in trends in chemical behaviour. This group has the defining characteristic that all the component elements have 5 electrons in their outermost shell, that is 2 electrons in the s subshell and 3 unpaired electrons in the p subshell. They are therefore 3 electrons short of filling their outermost electron shell in their non-ionized state. The most important element of this group is nitrogen (chemical symbol N), which in its diatomic form is the principal component of air.
Elements Group 16 (VIB,VIA):
valence electron is 6 the chalcogens or oxygen family- The chalcogens (pronounced /?kælk?d??n/) are the chemical elements in group 16 (old-style: VIB or VIA) of the periodic table. This group is also known as the oxygen family. It consists of the elements oxygen (O), sulfur (S), selenium (Se), tellurium (Te), the radioactive element polonium (Po), and the synthetic element ununhexium (Uuh). Although all group 16 elements of the periodic table, including oxygen are defined as chalcogens, oxygen and oxides are usually distinguished from chalcogens and chalcogenides. The term chalcogenide is more commonly reserved for sulfides, selenides, and tellurides, rather than for oxides. Oxides are usually not indicated as chalcogenides. Binary compounds of the chalcogens are called chalcogenides (rather than chalcides, which breaks the pattern of halogen/halide and pnictogen/pnictide).
Elements Group 17 (VIIB,VIIA):
valence electron is 7 the halogens or fluorine family- halogen elements are a series of nonmetal elements from Group 17 IUPAC Style (formerly: VII, VIIA) of the periodic table, comprising fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The artificially created element 117, provisionally referred to by the systematic name ununseptium, may also be a halogen. The group of halogens is the only periodic table group which contains elements in all three familiar states of matter at standard temperature and pressure. Owing to their high reactivity, the halogens are found in the environment only in compounds or as ions. Halide ions and oxoanions such as iodate (IO3 ?) can be found in many minerals and in seawater. Halogenated organic compounds can also be found as natural products in living organisms. In their elemental forms, the halogens exist as diatomic molecules. At room temperature and pressure, fluorine and chlorine are gases, bromine is a liquid and iodine and astatine are solids; Group 17 is therefore the only periodic table group exhibiting all three states of matter at room temperature.
Elements Group 18 (Group 0, VIIIA):
the helium family/neon family; for the first six periods, these are the noble gases- is any chemical element from the last column of the standard periodic table. For the first six periods, the group 18 elements are exactly the noble gases. However, the seventh member of group 18 (the synthetic element ununoctium) is probably not a noble gas. According to the classical shell model for electrons, the group 18 elements have a fully filled outer shell, rendering them inert to most chemical reactions. This holds true for the first six elements of this group (though they tend to become slightly less inert with increasing periods). For the seventh period group 18 element (ununoctium), this "nobility" is predicted to break down due to relativistic effects. valence electron is 8. Except for helium, which has only two valence electrons.
Identify the number of valence electrons for each of these groups.
Atoms of the first group, which includes hydrogen, lithium, and sodium, each have a single valence electron. The atoms of the second group, including beryllium and magnesium, each have two valence electrons. Similarly, atoms of the last group, including helium, neon, and argon, each have their outermost shells filled to capacity with valence electrons?two for helium, and eight each for neon and argon.
How does the number of valence electrons affect the properties of each group of elements?
The number of valence electrons affects the properties of each group of elements, since the valence electrons are the electrons in the highest energy level, they are the most exposed of all the electrons and, consequently, they are the electrons that get most involved in chemical reactions. In Lewis electron dot diagram, you can see how many valence electrons a particular element has. An electron dot diagram consists of the element's symbol surrounded by dots that represent the valence electrons. Typically the dots are drawn as if there is a square surrounding the element symbol with up to two dots per side. You can determine how many valence electrons an element has by determining which group it is in.
How can you determine the number of neutrons in an isotope if you know the atomic number?
The total number of neutrons in an isotope can be calculated by subtracting its atomic number from its mass number
How does an atom of carbon-14 differ from an atom of carbon-12?
Carbon-12 and carbon-14 both have the same number of protons and electrons because they are the same element. They differ in the number of neutrons found in the nucleus. Carbon-14 isotope is radioactive and has eight neutrons. While the most common isotope, carbon-12, has six neutrons and is not radioactive.
Does this difference between carbon isotopes affect how carbon behaves in a chemical reaction?
The difference between carbon isotopes does not affect carbon's behavior in the chemical reaction.
Why is this difference important for isotopic dating of organic remains?
The difference between isotopic dating of organic remains is important because scientists are able to calculate the age of carbon containing artifacts or remains, such as wooden tools or skeletons, by measuring their current level of radioactivity. This process, known as carbon-14 dating, enables us to probe as much as 50,000? 60,000 years into the past. Beyond this time span, there is too little carbon- 14 remaining to permit accurate analysis.
Explain how the number of valence electrons in an atom affects its ability to bond with other atoms.
The number of electrons in an atom's outermost valence shell governs its bonding behavior. Atoms tend to attract additional valence electrons to attain a full valence shell. This can be achieved one of two ways: an atom can either share electrons with neighboring atoms, a covalent bond, or it can remove electrons from other atoms, an ionic bond.
Why do atoms form chemical bonds?
This tendency is called the octet rule: Atoms tend to form chemical bonds so that they each have eight electrons in their valence shells, similar to the electron configuration of a noble gas.
Compare the bonding behavior of Na (sodium) and Ne (neon).
Sodium readily gives up the single electron in its third shell. This makes the second shell, which is already filled to capacity, the outermost occupied shell. Neon gains or loses electrons to acquire the outer shell electron configuration of a noble gas.
Explain how elements form an ionic bond.
type of chemical bond that involves a metal and a nonmetal ion (or polyatomic ions such as ammonium) through electrostatic attraction. In short, it is a bond formed by the attraction between two oppositely charged ions. The metal donates one or more electrons, forming a positively charged ion or cation with a stable electron configuration. These electrons then enter the non metal, causing it to form a negatively charged ion or anion which also has a stable electron configuration. The electrostatic attraction between the oppositely charged ions causes them to come together and form a bond. ionic bond is formed when an atom that tends to lose electrons is placed in contact with an atom that tends to gain them.
What is unique about a metallic bond?
Two or more metals can be bonded to each other by metallic bonds. This occurs, for example, when molten gold and molten palladium are blended to form the homogeneous solution known as white gold. The quality of the white gold can be modified simply by changing the proportions of gold and palladium. White gold is an example of an alloy, which is any mixture composed of two or more metallic elements.
How do elements form a covalent bond?
covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms, and other covalent bonds. In short, the attractionto- repulsion stability that forms between atoms when they share electrons form covalent bond of the elements. A covalent bond is formed when two atoms that tend to gain electrons are brought into contact with each other.
How can you use the periodic table to predict which atoms are likely to bond together?
You?ve learned that an ionic bond is formed when an atom that tends to lose electrons is placed in contact with an atom that tends to gain them. A covalent bond, by contrast, is formed when two atoms that tend to gain electrons are brought into contact with each other. Atoms that tend to form covalent bonds are therefore primarily atoms of the nonmetallic elements in the upper right corner of the periodic table (with the exception of the noble gas elements, which are very stable and tend not to form bonds at all). Hydrogen tends to form covalent bonds because, unlike the other group 1 elements, it has a fairly strong attraction for an additional electron. Two hydrogen atoms, for example, covalently bond to form a hydrogen molecule, H2. The number of covalent bonds an atom can form is equal to the number of additional electrons it can attract, which is the number it needs to fill its valence shell. Hydrogen attracts only one additional electron, and so it forms only one covalent bond. Oxygen, which attracts two additional electrons, finds them when it encounters two hydrogen atoms and reacts with them to form water, H2O. In water, not only does the oxygen atom have access to two additional electrons by covalently bonding to two hydrogen atoms but each hydrogen atom has access to an additional electron by bonding to the oxygen atom. Each atom thus achieves a filled valence shell.
What is the difference between polar and nonpolar covalent bonds?
A chemical bond that has a dipole and nonpolar has no dipole.
What is the difference between organic and inorganic compounds?
Inorganic compounds do not contain carbon.
What is a hydrocarbon?
an organic chemical compound containing only hydrogen and carbon atoms arranged in rows, rings, or both, and connected by single, double, or triple bonds. Hydrocarbons constitute a very large group including alkanes, alkenes, and alkynes.
DNA (deoxyribonucleic acid)
it consists of two long polymers of simple units called nucleotides, with backbones made of sugars and phosphate groups joined by ester bonds. These two strands run in opposite directions to each other and are therefore anti-parallel. Attached to each sugar is one of four types of molecules called bases.
RNA (ribonucleic acid).
is a biologically important type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nitrogenous base, a ribose sugar, and a phosphate. RNA is very similar to DNA, but differs in a few important structural details: in the cell, RNA is usually single-stranded, while DNA is usually double-stranded; RNA nucleotides contain ribose while DNA contains deoxyribose (a type of ribose that lacks one oxygen atom); and RNA has the base uracil rather than thymine that is present in DNA.
How would the opposing strand differ if it was a strand of RNA instead of DNA?
Adenine will pair with uracil (A?U) instead of T and guanine will still pair with cytosine (G?C).
Describe the difference between a pure substance and a mixture.
made up of one type of submicroscopic particle. For an ionic compound, that particle is an ion; for a covalent compound, it is a molecule; and for an element, it is an atom while a mixture is when two or more different substances are mixed together but are not combined chemically. The molecules of two or more different substances are mixed in the form of alloys, solutions, suspensions, and colloids. While there are no chemical changes to its constituents, the physical properties of a mixture, such as its melting point, may differ from those of the components. Some mixtures can be separated into their components by mechanical means; azeotropes cannot, at least not directly. Mixtures are the product of a mechanical blending or mixing of chemical substances like elements and compounds, without chemical bonding or other chemical change, so that each ingredient substance retains its own chemical properties and makeup
What is the difference between a heterogeneous and homogeneous mixture?
Mixture refers to the physical combination of two or more substances the identities of which are retained. Mixtures can be either homogeneous or heterogeneous. A homogeneous mixture is a type of mixture in which the composition is uniform. A heterogeneous mixture is a type of mixture in which the composition can easily be identified, as there are two or more phases present. Air is a homogeneous mixture of the gaseous substances nitrogen, oxygen, and smaller amounts of other substances. Salt, sugar, and many other substances dissolve in water to form homogeneous mixtures. A homogeneous mixture in which there is both a solute and solvent present is also a solution.
What is a solution?
A homogeneous mixture consisting of ions or molecules a substance consisting of two or more substances mixed together and uniformly dispersed, most commonly the result of dissolving a solid, fluid, or gas in a liquid.
air (oxygen and other gases in nitrogen), oxygen in water, alcoholic beverages, sugar in water
air (oxygen and other gases in nitrogen), oxygen in water, alcoholic beverages, sugar in water
Describe thermal energy and temperature.
Thermal (internal) energy is the total energy (kinetic plus potential) of the Sub-microscopic particles that make up a substance while the temperature is a measure of the hotness or coldness of substances, related to the average translational kinetic energy per molecule in a substance; measured in degrees Celsius, or in degrees Fahrenheit, or in kelvins.
Explain how thermal expansion affects substances.
Thermal expansion is the tendency of matter to change in volume in response to a change in temperature. When a substance is heated, its particles begin moving and become active thus maintaining a greater average separation.
What happens to the structure of water when it melts and freezes?
When ice melts; not all the six-sided crystals collapse. Some of them remain in the ice-water mixture, making up a microscopic slush that slightly ?bloats? the water, increasing its volume slightly (Figure 6.20). This results in ice water being less dense than slightly warmer water. As the temperature of water at 0°C is increased, more of the remaining ice crystals collapse. This further decreases the volume of the water. This contraction occurs only up to 4°C. That?s because two things occur at the same time?contraction and expansion. Volume tends to decrease as ice crystals collapse, while volume tends to increase due to greater molecular motion. The collapsing effect dominates until the temperature reaches 4°C. After that, expansion overrides contraction, because most of the ice crystals have melted. When ice water freezes to become solid ice; its volume increases tremendously? and its density is therefore much lower. That?s why ice floats on water. Like most other substances, solid ice contracts without further cooling. This behavior of water is very important in nature. If water were most dense at 0°C, it would settle to the bottom of a lake or pond. Because water at 0°C is less dense, it floats at the surface. That?s why ice forms at the surface
Explain the differences between solids, liquids, and gases.
Solids are Matter that has a definite volume and a definite shape. Liquid is Matter that has a definite volume but no definite shape, assuming the shape of its container. Gas is Matter that has neither a definite volume nor a definite shape, always filling any space available to it.
How does the addition of heat energy affect the motion of molecules?
In solid matter, the attractions between particles are strong enough to hold them in some fixed three-dimensional arrangement despite their random, thermal motion. The particles are able to vibrate about fixed positions, but they cannot move past one another. Adding heat causes these vibrations to increase until, at a certain temperature, the vibrations are strong enough to disrupt the fixed arrangement. The particles can then slip past one another and tumble around, much like a bunch of marbles in a bag. Further heating causes the particles in the liquid to move with such high amplitude vibrations that the attractions they have for one another can?t hold them together.
A substance is often characterized by its boiling point, which is the temperature at which it boils. At sea level, the boiling point of fresh water is 100°C
A liquid can be heated so that it becomes a gas?evaporation. As heat is added, the particles of the liquid acquire more kinetic energy and move faster. Particles at the liquid surface eventually gain enough energy to jump out of theliquid and enter the air. In other words, they enter the gaseous phase.
solid to gas, while at no point becoming a liquid molecules jump directly from the solid to the gaseous phase. Mothballs are well known for their sublimation. Ice also sublimes. Because water molecules are so tightly held in a solid, frozen water sublimes much more slowly than liquid water evaporates.
liquid turns into a solid when its temperature is lowered below its freezing point. As heat is withdrawn from the liquid, particle motion diminishes until the particles, on average, are moving slowly enough for attractive forces between them to take permanent hold. The only motion the particles are capable of then is vibration about fixed positions, which means the liquid has solidified, or frozen.
solid deposition of water vapor from saturated air. Water vapor condenses high in the atmosphere, forming clouds. It condenses close to the ground as well. When condensation in the air occurs near Earth?s surface, we call it dew, frost, or fog. On cool, clear nights, objects near the ground cool down more rapidly than the surrounding air. As the air cools to its dew point, it cannot hold as much water vapor as it could when it was warmer. Water from the now-saturated air condenses on any available surface.
gaseous phase into liquid phase, and is the reverse of evaporation This process can occur when the temperature of a gas decreases.
How does a chemical change differ from a physical change?
Any change in a substance that involves a rearrangement of the way its atoms are bonded is called a chemical change. in a physical change, a change in appearance is the result of a new set of conditions imposed on the same material. Restoring the original conditions restores the original appearance; we say a physical change is easy to reverse. The freezing and melting of water is a good example. Second, in a chemical change, a change in appearance is the result of the formation of a new material that has its own unique set of physical properties. Most chemical changes, therefore, are not so easy to reverse. The more evidence you have suggesting that a different material has been formed, the greater the likelihood that the change is a chemical change. Iron is a material that can be used to build cars. Rust is not. This suggests that the rusting of iron is a chemical change.
Explain why some materials are conductors while some are insulators.
because of the electrons, Electrical conductors are materials that allow charged particles (usually electrons) to pass through them easily. Copper, silver, and other metals are good electrical conductors for the same reason they are good heat conductors: atoms of metals have one or more outer electrons that are loosely bound to their nuclei. These are called free electrons. It is these free electrons that conduct through a metallic conductor when an electric force is applied to it, making up a current. (A current is a flow of charged particles, usually electrons). The electrons in other materials?rubber and glass, for example?are tightly bound and belong to particular atoms. Consequently, it isn?t easy to make them flow. These materials are poor electrical conductors for the same reason they are generally poor heat conductors. Such a material is called a good insulator.
Why is it useful to have materials with different properties?
It is useful to have materials with different properties to have different applications.
Why does water expand when it freezes?
The expansion upon freezing comes from the fact that water crystallizes into an open hexagonal form. This hexagonal lattice contains more space than the liquid state. While the hexagonal ice form discussed above is the primary form of ice and is the dominant form from the freezing point at 273K down to about 72 K.
is an opaque, yellowish substance that is a solid at room temperature and has a density of 19.3 grams per milliliter.
is a transparent substance that is a solid at room temperature and has a density of 3.5 grams per milliliter.
is a transparent substance that is a liquid at room temperature and has a density of 1.0 gram per milliliter.
a shiny grayish white metallic element that has the highest thermal and electric conductivity of any substance.
bluish-white, lustrous, diamagnetic metal, though most common commercial grades of the metal have a dull finish. It is somewhat less dense than iron and has a hexagonal crystal structure.
non-metallic element that exists in two main forms, diamond and graphite, and has the ability to form large numbers of organic compounds. Source: coal, petroleum..
The nonmetallic elements, with the exception of hydrogen, are on the right of the periodic table. Nonmetals are very poor conductors of electricity and heat, and they may also be transparent.
How does differentiation account for the different densities of Earth?s layers?
Differentiation the process by which gravity separates materials of different densities. (A mixture of oil and water undergoes differentiation, for example, when the denser water sinks to the bottom and the less-dense oil rises to the top.) Similarly, when Earth was a hot fluid mass, it formed layers through the process of differentiation.
Describe the characteristics and properties of minerals?
Minerals vary in color, luster, specific gravity, cleavage, fracture, tenacity, hardness and transparency. And the Special Properties of minerals are magnetism, chatoyancy, fluorescence, odor, streak, burn test, conductivity It is naturally occurring (formed naturally rather than manufactured.), It is a solid, It has a definite chemical composition, It is generally inorganic?it?s not alive and is not derived from living things, It has a characteristic crystalline structure. (The particles in it?atoms, ions, or molecules?are positioned in a specific, orderly arrangement.)
Graphite and diamond contain pure carbon and are called polymorphs. What is different about the structure and stability of these two minerals?
Diamond is among the hardest materials known. It is the ultimate abrasive, an excellent electrical insulator, best known naturally occurring thermal conductor, highly transparent and crystallizes in the cubic system. Graphite is one of the softest materials known. It is a very good lubricant, a conductor of electricity, is opaque. Some forms of graphite are used for thermal insulation (i.e. firebreaks and heat shields) and it crystallizes in the hexagonal system.
Explain the process of crystallization in mineral formation.
starts as single microscopic crystals form whose boundaries are flat, planar surfaces. As more and more atoms bond to the microscopic crystal, the crystal grows from the outside. Minerals crystallize from two primary sources: magma and water solutions. Consider first minerals that crystallize out of magma. Magma is molten rock found unde rground. There are a few major types of magma with differing compositions, but, in general, magmas are hot fluids with a texture like thick oatmeal. They contain some solids and gases, but magma is consist mainly of freely flowing atoms from the silicate group of minerals?silicon, and oxygen, plus aluminum, potassium, sodium, calcium, and iron. When magma starts to cool, the hot liquid atoms lose kinetic energy. Then the attractive forces among them pull the atoms into orderly crystal structures. Minerals crystallize systematically based upon their melting points. The first minerals to crystallize from magma have the highest melting points and, the last minerals to crystallize have the lowest melting points. Minerals crystallize out of water solutions as well.
contain both silicon (Si) and oxygen (O). Most silicates contain other elements in their crystal structure as well. Oxygen is the most abundant element in Earth?s crust; silicon is the second most abundant. Together these two elements constitute about 75% of the Earth?s crust, as shown in Figure 23.2. Silicon has a great affinity for oxygen. In fact, silicon has such a strong tendency to bond with oxygen that silicon is never found in nature as a pure element; it is always chemically combined with oxygen. For these reasons, the silicates are the most common mineral group, constituting 92% of the Earth?s crust. minerals make up just 8% of the Earth?s crust by mass.
The nonsilicates include the carbonates, oxides, and such native elements as gold and silver, and a few others. The carbonates are the most abundant nonsilicate minerals. The carbonate minerals have a much simpler chemical structure than the silicates. Carbonate structure is triangular, with a central carbon atom bonded to three oxygen atoms, . Groups of carbonate ions are arranged in sheets. Two common carbonate minerals are calcite and dolomite. Calcite consists of the chemical compound calcium carbonate, CaCO3. Dolomite is a mixture of calcium carbonate and magnesium carbonate, CaMg(CO3)2. Calcite and dolomite are the main minerals found in the group of rocks called limestone
What is the structural unit of silicates?
silicon (Si) and oxygen (O). Most silicates contain other elements in their crystal structure as well.
List examples of minerals that are silicates and those that are nonsilicates.
Silicates- Olivine, Quartz, biotite,Muscovite,Orthoclase Nonsilicates- Colcite,gypsum,Apatite,Pyrite,Hematite
Fool?s Gold,? typically forms cubic crystals marked with parallel lines called ?striations.?
a magnesium iron silicate with the formula (Mg,Fe)2SiO4. It is one of the most common minerals on Earth, and has also been identified in meteorites, the Moon, Mars, in the dust of comet Wild 2, within the core of comet Tempel 1, as well as on asteroid 25143 Itokawa
coarse-grained sedimentary rock containing fragments of other rock larger than 2 mm/0.08 in. in diameter
a coarse-grained high-grade metamorphic rock formed at high pressures and temperatures, in which light and dark mineral constituents are segregated into visible bands.
sedimentary rock formed from the skeletons and shells of ocean organisms that consist chiefly of calcium carbonate. Use: in construction, in making lime and cement.
a white, reddish, or greenish mineral consisting of calcium magnesium carbonate. Source: sedimentary rocks. Use: building stone, cement, fertilizers.
a hard, black, often glassy, volcanic rock. It was produced by the partial melting of the Earth's mantle.
a shiny aluminosilicate mineral belonging to a group having varying compositions. Source: igneous and metamorphic rocks. Use: electrical insulators, heating elements.
a colorless or white crystalline mineral consisting of sodium chloride. Source: dried up lake beds. Use: table salt, source of chlorine.
a common, hard, usually colorless, transparent crystalline mineral with colored varieties. Use: electronics, gems.
Explain how seismic waves are used to determine the structure of the Earth?s interior.
The study of measurement of seismic wave has provided most of what we know today about Earth's interior. Like any kind of wave, seismic waves reflect from surfaces and refract through others. Exactly how seismic waves reflect and refract, as well as variations in their speed and wavelength, reveals much about the medium in which these waves travel. Seismic waves come in two main varieties: body waves, which travel through the Earth?s interior, and surface waves, which travel on the Earth?s surface like ripples on water. secondary waves (S-waves). Primary waves are longitudinal?they compress and expand the material through which they move. P-waves are the fastest seismic waves, traveling at speeds between 1.5 and 8 km per second through any type of material?solid rock, magma, water, and air. S-waves, on the other hand, are transverse?they vibrate the particles of their medium up-and-down and side to side, and they travel more slowly than P-waves. Swaves can only travel through solid materials. Surface waves come in two types: Rayleigh waves and Love waves (each named after its discoverer). Rayleigh waves roll over and over in a backward tumbling motion similar to ocean waves, except that ocean waves tumble in a forward direction. Love waves move just like S-waves, except the shaking motion is horizontally side-to-side. Since Love waves shake things side-to-side, they are particularly damaging to tall buildings.
What is the Mohorovicic discontinuity (Moho)?
The dividing line between the Earth?s crust and mantle
Where are mountain roots, important in isostasy, located?
Mountains are supported from below by ?roots? that extend deep into the mantle. Taller mountains have deeper roots that maintain their isostatic balance. Why? As erosion carries the top of a mountain away over time, like an iceberg with its top shaved off, the lightened mountain is buoyed higher. So the submerged portion of continental crust also raises to shallower depths
The upper mantle itself is divided into two zones. The uppermost zone, directly beneath the crustal surface, is relatively cool and rigid. In many ways, it behaves like the stiff and breakable crust. In fact, because the crust and the upper region of the upper mantle are so similar, they act as a single layer of relatively rigid rock.
Asthenosphere is solid, it actually flows over long periods of geologic time.* It behaves in a plastic manner. This is similar to Silly Putty or taffy; which acts like a solid under sudden stress (it can break) but behaves like a fluid when stress is applied to it slowly (it can flow). Hence, the rigid lithosphere rides like a raft on the slowly flowing asthenosphere. Beneath the asthenosphere, into the remaining 2,200 km of lower mantle, the rock becomes more rigid again. Although the lower mantle retains the ability to flow, it isn?t as plastic as the overlying asthenosphere.
Explain what happens in the outer core when the Earth spins.
As Earth rotates, this liquid outer core spins. Convection currents in the outer core are stirred up. These motions in the core have effects far outside the Earth?s surface. The moving iron and other metals produce a flowing electric charge?a current. It is this electric current that creates Earth?s magnetic field.
Explain why Wegener?s hypothesis of continental drift failed and the evidence that was needed to support his predictions.
Wegener supported his hypothesis of continental drift with impressive biological, geological, and climatological evidence, which he put forth in his book The Origins of Continents and Oceans, published in 1912. Wegener cited fossil evidence?that nearly identical land-dwelling animals and plants had once lived in (what are today) South America and Africa and nowhere else. This was a strange finding because, today, animals and plants of these regions are notable for their striking differences. Also, fossils of the plants Glossopteris flora, shown in, were found in rocks in India, Australia, South America, Africa, and Antarctica. Seeds from the plants were too large to have been distributed by air. How could these plants be the result of parallel evolution in such widely separated regions? To explain the fossils, geologists of Wegener?s time proposed that prehistoric land bridges once connected the continents. Yet there was no physical evidence that such land bridges ever existed. Continental drift provided a neat explanation for the fossil findings. The continents had once been a single landmass, with a single community of animals and plants. When the continents later split along the present day Mid-Atlantic Ocean, species were allowed to evolve independently in separate environments. Wegener also found matching rock types on both sides of the Atlantic. For example, diamond-bearing formations occur in corresponding locations in Africa and South America on opposite sides of the Atlantic Ocean. Further, in many cases, the orientation of folds in mountain chains of the same age is continuous across the oceans?both in North America and Europe and in South America and Africa. Besides the matching of fossils, rock types, and mountain folds, still more evidence supported Wegener?s hypothesis. For example, continental drift explained puzzling evidence of ancient ice sheets on regions now located near the equator. When these regions were covered by ice sheets, they were located near the South Pole. Also, the location of young mountains along the edges of the continents was explained by the crumpling of Earth?s crust when landmasses collided. Yet Wegener?s hypothesis was generally dismissed in scientific circles.
Summarize plate tectonics.
is a scientific theory which describes the large scale motions of Earth's lithosphere. The theory builds on the older concepts of continental drift, developed during the first decades of the 20th century by Alfred Wegener, and seafloor spreading, developed in the 1960s. The lithosphere is broken up into what are called tectonic plates. In the case of Earth, there are currently seven to eight major (depending on how they are defined) and many minor plates. The lithospheric plates ride on the asthenosphere. These plates move in relation to one another at one of three types of plate boundaries: convergent, or collisional boundaries; divergent boundaries, also called spreading centers; and transform boundaries. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along plate boundaries. The lateral relative movement of the plates varies, though it is typically 0?100 mm annually. Tectonic plates are able to move because the Earth's lithosphere has a higher strength and lower density than the underlying asthenosphere. Their movement is thought to be driven by the motion of hot material in the mantle. Lateral density variations in the mantle result in convection, which is transferred into tectonic plate motion through some combination of drag, downward suction at the subduction zones, and variations in topography and density of the crust that result in differences in gravitational forces.
What are convection currents?
Uneven heating of Earth?s surface underlies the differences in air pressure that produce winds. Because warm air expands and cool air contracts, warm air is characterized by low density and low air pressure, while cool air is characterized by high density and high pressure. As air heated at Earth?s surface becomes less dense and rises, it cools, moves laterally, and then sinks, only to be heated by the surface and to rise again. This upward, horizontal, and downward movement of air is called a convection cell. The vertically rising air in a convection cell is called a convection current. The average horizontal motion is called wind.
What is the role of convection currents in plate tectonics?
Local differences in surface heating give rise to small-scale convection cells and pressure gradients, and these create small-scale local winds. Planet-scale temperature differences that occur because equatorial regions experience greater solar intensity produce much larger convection cells and pressure gradients. These give rise to global wind patterns called prevailing winds.
occur where plates slide or, perhaps more accurately, grind past each other along transform faults. The relative motion of the two plates is either sinistral (left side toward the observer) or dextral (right side toward the observer). The San Andreas Fault in California is an example of a transform boundary exhibiting dextral motion.
occur where two plates slide apart from each other. Midocean ridges (e.g., Mid-Atlantic Ridge) and active zones of rifting (such as Africa's Great Rift Valley) are both examples of divergent boundaries.
Convergent boundaries (or active margins)
occur where two plates slide towards each other commonly forming either a subduction zone (if one plate moves underneath the other) or a continental collision (if the two plates contain continental crust). Deep marine trenches are typically associated with subduction zones. The subducting slab contains many hydrous minerals, which release their water on heating; this water then causes the mantle to melt, producing volcanism. Examples of this are the Andes mountain range in South America and the Japanese island arc.
Explain how convection cells cause the following types of air movement in the atmosphere: local winds and Hadley cells.
The pair of convection cells between 0° and 30° north and south which produce the prevailing winds are called Hadley cells. There are two other pairs making a total of six Hadley cells on Earth?s surface. Although most of the air that sinks at 30° north and south latitude returns to the equator, some of it moves poleward. Somewhere around 60° north and south, this low-altitude air flowing from the equator meets cold air coming from the poles. The air moving in from the lower latitudes is usually warmer, and so it is buoyed upward by the cold, polar air. It then moves back to the equator, cooling and finally sinking at about 30° north and south. This sinking air contributes to the high-pressure air found at 30° north and south while adjacent surfaces may have different temperatures because of compositional or topographic differences between them. A notable example occurs where water meets land. The land heats and cools more rapidly than water, primarily due to water?s high specific heat capacity. (As you learned in Chapter 6, specific heat capacity is the quantity of heat required to change one gram of a substance by 1°C. You can think of it as thermal inertia?the higher the specific heat capacity of a substance, the more resistant it is to changing its temperature.) The specific heat capacity of water is 5 times the specific heat of soil; hence, water absorbs much more heat than soil before it warms by the same amount. As an example, consider land and sea breezes. During the day, land gets hotter faster than the ocean because land has a lower specific heat capacity. The hot air over the warmed land rises, creating an area of lower air pressure. The cooler, higher-pressure air from over the ocean then blows from the sea to the land. This is a sea breeze. But at night, the land cools off faster than the sea, again because of its low specific heat capacity relative to water. Cooler air descends over the land and so creates an area of higher pressure. Wind blows from the land to the sea. This is a land breeze.
Describe mechanical and chemical weathering of rocks.
Mechanical weathering, usually caused by water, physically breaks rock down into smaller pieces. Ice wedging, is an example. In this process, water seeps into rock, freezes and expands, and eventually melts and contracts. This physically pushes sections of rock apart. Biological agents, such as trees, may produce mechanical weathering, too. Chemical weathering is actually the main producer of sediment. In chemical weathering, the compounds in rock decompose into substances that are more stable in the surface environment. Again, water is the main agent. When rain falls, it reacts with carbon dioxide in the air and soil to produce carbonic acid, which makes rainwater slightly acidic. When it seeps downward into rock, acidified rainwater can partially dissolve the rock and alter the minerals it contains
wedging-Is a form of mechanical weathering (that is, weathering that involves physical, rather than chemical change). Frost wedging is caused by the repeated freeze-thaw cycle of water in extreme climates.
Exfoliation is a form of mechanical weathering in which curved plates of rock are stripped from rock below. This results in exfoliation domes or dome-like hills and rounded boulders.
solids expand when heated and contract when cooled. Although such expansion due to changes in temperature from day to night or from summer to winter may contribute to rock disintegration, experiments indicate it has only a minor effect.
similar to frost wedging, the force of growing salt crystals in fractures and pore spaces can pry loose grains and expand openings. Such a process is important in arid and coastal areas.
Is another wedging phenomenon. A tree root tips are tiny and penetrate easily into fine fractures of rocks. As the roots grow in diameter, they put stress on the rock that can cause the fractures to expand. Roots of large trees can be several inches in diameter. As they grow to this size they can cause significant separation in rock fractures.
dissolving of minerals into solution. Most minerals have low solubility in pure water, but rain contains carbonic acid, so that carbonate minerals dissolve readily in acidic solutions.
atmospheric oxygen combines with metal ions to form oxides (orhydroxides). Oxidation of pyrite, for example, produces sulfuric acid.
hydrolysis-reaction between a mineral and water can produce a new mineral or dissolved material. Hydrolysis of feldspar, for example, produces clay.
Explain the process of erosion.
Mass wasting is the down-slope movement of rock and sediments, mainly due to the force of gravity. Mass movement is an important part of the erosional process, as it moves material from higher elevations to lower elevations where other eroding agents such as streams and glaciers can then pick up the material and move it to even lower elevations. Mass-movement processes are always occurring continuously on all slopes; some mass-movement processes act very slowly; others occur very suddenly, often with disastrous results.
Describe the action of the following erosional agents: gravity, surface water, groundwater, wind, and glaciers.
It is gravity that causes rain to fall, and it also moves the water down slope once it is on the surface of the earth. As water moves down slope, it cuts river channels, which can become deep valleys. Water on Earth is constantly circulating, driven by the heat of the Sun and the force of gravity. As the Sun?s energy evaporates water, a cycle begins Evaporation moves water molecules from Earth?s surface to the atmosphere?the thin envelope of gases surrounding the Earth. The resulting moist air may be transported great distances by the wind. Some of the water molecules condense to form clouds and then precipitate as rain, sleet, or snow. The total amount of water vapor in the atmosphere remains relatively constant, because evaporation and condensation balance each other. If precipitation falls on the ocean, the cycle is complete?water goes from the ocean back to the ocean. A longer cycle occurs when precipitation falls on land, for water may drain to streams, then rivers, and then journey back into the ocean. Or it may soak deep into the ground which we call groundwater, or evaporate back into the atmosphere before reaching the ocean. Also, water falling on land may become part of a snow pack or a glacier. Although snow or ice may lock up water for many years, it eventually melts or evaporates, so the water once again can move through the cycle. This natural circulation of water is known as the hydrologic cycle or, simply, the water cycle. One part of the water cycle has particular relevance to the shaping of Earth?s landforms, and that is the journey fresh water takes from the time it falls as rain, makes its way across Earth?s surface, and eventually returns to the ocean.
the lowest and most dense layer of the atmosphere, extending 10 to 20 km/6 to 12 mi, in which temperature decreases with rising altitude and most weather occurs
the region of the Earth's atmosphere between the troposphere and mesosphere, from 10 km/6 mi to 50 km/30 mi above the Earth's surface.
the layer of the Earth's atmosphere in which temperature decreases rapidly, located between the stratosphere and thermosphere
the region of the atmosphere above the mesosphere in which temperature steadily increases with height, beginning at about 85 km/53 mi above the Earth's surface
four layers of the Earth's upper atmosphere in which incoming ionizing radiation from space creates ions and free electrons that can reflect radio signals, enabling their transmission around the world
What gases make up Earth?s atmosphere?
Nitrogen, Oxygen, Argon, Carbon dioxide, Neon, Helium, Methane, Krypton, Hydrogen, Water vapor, Carbon monoxide, Sulfur dioxide, Nitrogen dioxide, Particles (dust, pollen) and Ozone
Which gases are found in trace amounts?
water vapor, argon, carbon dioxide, Oxygen, Ozone, Neon, Carbon monoxide, Helium, Sulfur dioxide, Methane, Hydrogen, and Particles (dust, pollen)
Explain the Coriolis effect?
As the Earth spins, all freely moving objects?air and water, aircraft and ballistic missiles, and even snowballs to a small extent?appear to deviate from their straight-line paths as the Earth rotates beneath them.This apparent deflection due to the rotation of the Earth is the Coriolis effect. A significant impact of the Coriolis effect is the apparent deflection of the winds toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere. The impact of the Coriolis effect varies according to the speed of the wind. The faster the wind, the greater the deflection. Latitude also influences the degree of deflection. Deflection is greatest at the poles and decreases to zero at the equator.
How does humidity differ from relative humidity?
Humidity is the amount of water vapor in air. More specifically, humidity is the mass of water vapor a given volume of air contains. While Relative humidity is the ratio of the amount of water vapor currently in the air compared with the largest amount of water vapor that it is possible for the air to hold at that temperature.
Describe the different types of air masses.
maritime arctic - cool, moist, unstable; continental arctic - cool, dry, stable; maritime polar - cool, moist, unstable; continental polar - cold, dry, stable; maritime tropical - warm, moist, usually unstable; continental tropical- hot, dry, stable aloft; unstable at surface
Explain the changes in weather that accompany a cold front. How do the changes differ when a warm front moves into an area?
Although the warmer air always rises vertically above the cooler air, the horizontal movements of the air masses vary. Sometimes, it?s the colder, denser air mass that advances into and displaces a stationary warm air mass. In this case, the contact zone between the air masses is called a cold front. But, if it?s the warm air that moves into territory that had been occupied by a cold air mass, the zone of contact is called a warm front.
Describe the changes in weather associated with a low-pressure center (cyclone) and a high-pressure center (anticyclone).
In meteorology a cyclone (or a low-pressure center or simply a low) is an area of low pressure around which winds flow. Due to the Coriolis effect, the winds in a cyclone move counter clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Since the cyclone?s center is the region of lowest pressure, air converges into the center, but it is then forced to rise upward. Rising air in a cyclone can produce clouds and precipitation, ranging from rain and thunderstorms in the summer and fall to rain, thunderstorms, and possibly snow in the winter. An anticyclone (or high-pressure center or high) is an area of high pressure. Air moves from high pressure to low, so air moves downward and outward from an anticyclone. This sinking motion leads to generally fair skies and no precipitation near the high. The Coriolis effect turns the moving air around a high-pressure center so that anticyclonic winds blow clockwise around a high in the Northern Hemisphere and counterclockwise around a high in the Southern Hemisphere.
an extremely destructive funnel-shaped rotating column of air that passes in a narrow path over land.
a severe tropical storm with torrential rain and extremely strong winds. Hurricanes originate in areas of low pressure in equatorial regions of the Atlantic or Caribbean, and then strengthen, traveling northwest, north, or northeast.
Describe the greenhouse effect.
The warming of the atmosphere that results from terrestrial radiation being trapped by these ?greenhouse gases.?
Summarize the effects of human activities on the levels of greenhouse gases.
There are many ways in which people are accelerating global temperature change, but two principal causes are the burning of fossil fuels and the cutting down of forests, a practice known as deforestation. Both of these activities accelerate temperature change. Fossil fuels contribute by adding carbon dioxide (CO2) to the atmosphere, and deforestation adds to the problem by removing the trees that absorb carbon dioxide from the troposphere. Carbon dioxide ranks as the numberone gas emitted by human activities. When speaking of atmospheric pollutants such as, say, sulfur dioxide, we talk in terms of millions of tons. The amount of carbon dioxide we pump into the atmosphere is measured in billions of tons. A single tank of gasoline in an automobile produces up to 90 kilograms of carbon dioxide. A jet plane flying from New York to Los Angeles releases more than 200,000 kg. Clearing and burning rainforests releases vast amounts of such greenhouse gases as carbon dioxide, methane, ozone, and nitrous oxide into the atmosphere. It is estimated that deforestation contributes 23?30% of all carbon dioxide in the atmosphere each year. Tropical deforestation also leads to global warming by destroying one of the Earth?s few ways to absorb excess atmospheric carbon. Through photosynthesis, forests absorb and store so much atmospheric carbon that scientists refer to tropical rainforests as ?carbon sinks.? Thus, while more and more carbon is released into the atmosphere, there are fewer and fewer forests to remove the carbon from the atmosphere.
Are instruments that measure motions of the ground, including those of seismic waves generated by earthquakes, nuclear explosions, and other seismic sources. Records of seismic waves allow seismologists to map the interior of the Earth, and locate and measure the size of these different sources.
Global Positioning System (GPS):
is a space-based global navigation satellite system that provides reliable location and time information in all weather and at all times and anywhere on or near the Earth there is an unobstructed line of sight to four or more GPS satellites.
Thermal imaging cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 900?14,000 nanometers or 0.9?14 Km) and produce images of that radiation, called thermograms. Since infrared radiation is emitted by all objects near room temperature, according to the black body radiation law, thermography makes it possible to see one's environment with or without visible illumination.
Satellite Remote Sensing:
Today, remote sensing is the primary tool for mapping landforms and observing rapid or slow changes on Earth?s surface. As the term is generally applied, remote sensing consists of imaging Earth?s surface with satellite-based cameras, radio receivers, scanners, thermal sensors, and other instruments. Such tools are used to create digital images, maps, and graphs of Earth?s surface features. Most often, remote-sensing devices gather data in the form of electromagnetic waves?visible light, infrared radiation, microwaves, etc. If an image, map, or graph is a ?satellite image,? you know it was obtained with remote-sensing technology. There are many remote-sensing applications. Satellite images are used for mapmaking and surveying, to detect temperature variations over Earth?s surface, and to track weather changes. Satellite images provide clues that point to subsurface deposits of mineral ores, oil, gas, and groundwater, and they help scienists and others to manage the land, the ocean, and the atmosphere. Satellite pictures also allow us to compare landscapes before and after such natural events as floods, earthquakes, and fires, and to assess the damage done.
Radar (Doppler Radar):
Doppler refers to the principle the Austrian scientist Christian Doppler discovered in 1842. Doppler worked out his ideas using sound waves, long before radio, much less radar, was invented. But the same principle applies to radar's radio waves and to light arriving from distant stars. All weather radars send out radio waves from an antenna. Objects in the air, such as raindrops, snow crystals, hailstones or even insects and dust, scatter or reflect some of the radio waves back to the antenna. All weather radars, including Doppler, electronically convert the reflected radio waves into pictures showing the location and intensity of precipitation. Doppler radars also measure the frequency change in returning radio waves. Waves reflected by something moving away from the antenna change to a lower frequency, while waves from an object moving toward the antenna change to a higher frequency. The computer that's a part of a Doppler radar uses the frequency changes to show directions and speeds of the winds blowing around the raindrops, insects and other objects that reflected the radio waves. Scientists and forecasters have learned how to use these pictures of wind motions in storms, or even in clear air, to more clearly understand what's happening now and what's likely to happen in the next hour or two.
An organism?s environment includes nonliving, or abiotic, features, such as temperature, sunlight, precipitation, rocks, ponds, and so forth.
Ecologists may study how a specific population uses resources, including what kinds of foods are eaten and what types of habitats are used.
What are examples of competition in ecosystems?
Anytime two species in a community use the same resource?one that exists in limited supply?they compete
What components are included in a species? niche?
A species? niche is defined as the total set of biotic and abiotic resources it uses within a community. This includes food eaten, water drunk, space occupied, and so forth.
A remora hitches a ride on a shark. The remora obtains protection from its hosts and feeds on leftover scraps from the shark?s meals.
fleas, tapeworms, and other organisms that live on or in their hosts and obtain nutrientsfrom them.
The fungus receives nutrients from the plant while helping the roots to absorb water and minerals
Describe the different types of terrestrial biomes and aquatic biomes.
Temperate Forest is found in areas with four distinct seasons, including a warm growing season and a cold winter. Temperatures vary considerably over the course of the year. Temperate forests receive between 75 and 150 centimeters of rainfall per year. Coniferous forest sometimes called evergreen forests, are found in areas with long, cold winters and short summers. They are relatively dry, receiving about 40 to 100 centimeters of precipitation per year, mainly in the form of snow. Tundra is found in areas of extreme cold and little precipitation. One of the defining features of tundra is a layer of permafrost, or permanently frozen subsoil, beneath the topsoil. Savannas are tropical grasslands with a warm climate and along dry season. They are covered with grass and occasional scattered trees. Savanna plants have longroots for dealing with drought, and the trees also have a thick bark that helps them survive periodic fires. Temperate grass land are found in areas with four distinct seasons, including a hot summer and cold winter. Temperate grasslands have more widely varying temperatures and less rainfall?about 50 to 90 centimeters per year?than savannas Chaparral is found in places with mild, rainy winters and hot, dry summers characterized by drought and fire. Deserts are habitats that receive very little precipitation, usually less than 50 centimeters per year. AQUATIC BIOMES: Freshwater habitats include the still waters of lakes and ponds and the flowing waters of rivers and streams. Lakes and ponds vary tremendously in size and in biodiversity. Saltwater Habitat .The oceans offer a wide range of habitats to living organisms. Many marine species are found in the pelagic zone?that is, they live in the watercolumn itself.
sometimes called rainforests, are found close to the equator. Temperatures are warm and fairly constant throughout the year. Tropical forests receive between 200 and 400 centimeters of rain a year, distributed between a wet season and a dry season.
receive between 75 and 150 centimeters of rainfall per year. Temperatures vary considerably over the course of the year.
are found in areas with long, cold winters and short summers. They are relatively dry, receiving about 40 to 100 centimeters of precipitation per year, mainly in the form of snow.
are tropical grasslands with a warm climate and a long dry season. Temperate grasslands have more widely varying temperatures and less rainfall?about 50 to 90 centimeters per year?than savannas.
is found in places with mild, rainy winters and hot, dry summers characterized by drought and fire.
are habitats that receive very little precipitation, usually less than 50 centimeters per year. Although deserts are usually associated with hot climates, cold deserts, in which precipitation generally falls as snow, also exist.
Describe primary and secondary succession.
Primary succession occurs when bare land, devoid of soil, is colonized by successive waves of living organisms. Primary succession begins when new land is formed by volcanic activity, for example, or when a glacier?s retreat reveals bare rock. Secondary succession occurs when a disturbance destroys existing life in a habitat but leaves soil intact. Fires and the abandonment of old farmland are examples of events that could initiate secondary succession.
What effect do regular moderate disturbances have on ecosystems?
According to the intermediate disturbance hypothesis, regular disturbances, if not too extreme, actually contribute to biodiversity. This is because different make use of different habitats.
species that live by making organic molecules out of inorganic materials and energy. Most producers photosynthesize but some may chemosynthesize
are organisms that break down dead organisms, and in doing so carry out the natural process of decomposition.
an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging
Explain the transfer of energy from the Sun through the food chain.
A food chain begins with producers, species that live by making organic molecules out of inorganic materials and energy. Most producers photosynthesize the process in plants and some other organisms in which light energy from the Sun is convertedto energy in organic molecules.
Describe how organisms use the energy contained in their food supply.
All organisms need energy in order to grow, reproduce, and perform the activities necessary for survival. In most ecosystems, energy comes ultimately from the Sun. Earth receives a lot of sunlight energy?about 1019 kilocalories reach Earth?s surface every day. Only a small fraction of this enters the biotic world, however, when plants and other organisms use it to build organic molecules during the process of photosynthesis. Photosynthesizing organisms convert about 1 percent of the sunlight energy that strikes them into organic matter. Although this may sound inefficient, it is still enough, globally, to build 170 billion tons of organic material a year.
What happens to energy as it moves from the first trophic level to the second and third trophic levels?
the amount of energy at each successive trophic level decreases. This is because not every organism at one trophic level is eaten by an organism at the next level and because some energy is lost to feces and maintenance.
Carbon is found in carbon dioxide molecules in the atmosphere and oceans. Producers move carbon into the biotic world during photosynthesis. Carbon is returned to the abiotic world as carbon dioxide, a product of cellular respiration. Most of the inorganic carbon on Earth exists as carbon dioxide and is found either in the atmosphere or dissolved in ocean waters. Carbon moves into the biotic world when plants and other producers convert carbon dioxide to glucose during photosynthesis. This carbon becomes available to other organisms as it passes up the food chain. Carbon is returned to the abiotic world as carbon dioxide, a product of cellular respiration
the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out via both biological and non-biological processes.
hydrologic (water) cycle:
water evaporates from the oceans into the atmosphere, is moved around the atmosphere by winds, and then precipitates as rain or snow over ocean or land. Water that falls on land eventually flows back to the oceans through rivers, streams, and groundwater. Water moves into the biotic world when it is absorbed or swallowed by organisms. Some of this water then passes up the food chain. The rest is returned to the abiotic environment in a variety of ways, including through respiration, perspiration, excretion, and elimination.
Temperate forest biome:
The soil of temperate forests is fertile, and these forests make good farmland.
Coniferous forest biome:
The ground in coniferous forests is usually covered with shed needles, and the soil is poor in nutrients.
Tropical forest biome:
most of the nutrients present in tropical forests are being used by one or another living organism?as a result, the soil tends to be poor.
a process by which green plants and other organisms turn carbon dioxide and water into carbohydrates and oxygen, using light energy from the sun trapped by chlorophyll. Is it also a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight.
hydrologic (water) cycle:
The hydrologic cycle also involves the exchange of heat energy, which leads to temperature changes. For instance, in the process of evaporation, water takes up energy from the surroundings and cools the environment. Conversely, in the process of condensation, water releases energy to its surroundings, warming the environment.
Planet-scale temperature differences that occur because equatorial regions experience greater solar intensity produce much larger convection cells and pressure gradients.
Small water droplets form at lower altitudes below the freezing level and ice crystals at high altitudes. In some cases, high clouds may be partly composed of supercooled water droplets. The droplets and crystals are typically about 0.01 mm (0.00039 in) in diameter. The most common agents of upward motion causing condensation are convective lift caused by daytime solar heating of the air at surface level, frontal lift that forces a warmer air mass to rise over top of a cooler airmass, and orographic lift of the air over mountains. When air rises, it expands as the pressure decreases.
About 50% of the Sun's energy is absorbed at the Earth's surface and the rest is reflected or absorbed by the atmosphere. The reflection of light back into space - largely by clouds - does not much affect the basic mechanism; this light, effectively, is lost to the system
Explain how heterotrophs, autotrophs, and chemoautotrophs obtain energy.
from sunlight or inorganic compounds
Describe how Darwin?s observations supported his hypothesis that heritable traits change over time.
What is natural selection?
Organisms with heritable, advantageous traits leave more offspring than organisms with other traits, causing advantageous traits to become more common in populations over time.
Traits that are passed from parents to offspring because they are at least partially determined by genes.
The number of offspring an organism produces in its lifetime compared to other organisms in the population.
Describe an example of a population that changes due to natural selection.
During the Industrial Revolution, coal was the primary fuel in England. Burning coal slathered dark soot on trees, rocks, and ground. And then a startling thing happened to the moths. Peppered moths in England had always been light in color, with the scattering of dark peppery flecks that gave them their name. Their coloration made them hard to see against a habitat of lichen-covered trees and rocks
Why are adaptations an important component of a species? survival?
Natural selection acts as the driving force behind evolution because it leads to the evolution of adaptations?traits that make organisms well suited to living and reproducing in their environments. Adaptations can relate to many different aspects of an organism?s life. Many of the adaptations organisms evolve help them survive. Survival is, after all, usually a requirement for leaving offspring.
Describe how animals are adapted to survive in hot or cold environments.
Animals that live in extremely hot or extremely cold habitats need to be able to maintain appropriate body temperatures in those environments?to thermoregulate. In deserts, animals have to be able to dissipate heat to avoid overheating. In cold habitats, animals have to be able to retain heat. In both types of environments, animals have evolved behavioral, physiological, and anatomical adaptations relating to heat balance.
As with body structures, the macromolecules of organisms retain evidence of their shared evolutionary history. For example, the DNA of related species have similar ACGT sequences. This is true not only for sequences in the DNA molecule that tell cells how to build proteins but even for sequences that have no obvious function (Chapter 16). This sequence similarity, and the fact that DNA sequences tend to be more similar in more closely related species, is logically explained by shared evolutionary history.
natural selection and adaptation:
Natural selection has produced remarkable adaptations over time. Nature does not plan ahead?it does not plan to make a falcon or a polar bear. Instead, adaptations are built step-by-step, through the never-ending selection of the most successful forms that arise from chance mutations.
antibiotic resistance bacteria:
Microorganisms evolve resistance through natural selection acting upon random mutation. Once a gene conferring resistance arises to counteract an antibiotic, not only can that bacterium thrive, but it can spread that gene to other types of bacteria through horizontal gene transfer of genetic information by plasmid exchange. It is unclear whether the genetic information responsible for antibiotic resistance typically arises from an actual mutation, or is already present in the gene pool of the population of the organism in question.
Originally, the vast majority of peppered moths had light colouration, which effectively camouflaged them against the light-coloured trees and lichens which they rested upon. However, because of widespread pollution during the Industrial Revolution in England, many of the lichens died out, and the trees that peppered moths rested on became blackened by soot, causing most of the light-coloured moths, or typica, to die off from predation. At the same time, the dark-coloured, or melanic, moths, carbonaria, flourished because of their ability to hide on the darkened trees.[
Humans are primates, a group of mammals that also includes the monkeys and apes. This does not mean we are descended from any modern species of monkey or ape, just that we share a common more recent ancestor with these species than we do with a dog, or frog, or plant. Humans are also hominids, the group within the primates that includes modern Homo sapiens as well as some of our extinct relatives. Although humans are the only hominids in existence today, fossil hominids provide clues as to how humans evolved.
are morphological or physiological similarities between different species of plants or animals. is the source of most traditional evidence for evolution and common descent. It continue to provide many examples of deep relationships between species which are best or only explained through evolutionary theory when the similarities simply don't make sense from a functional perspective.
is the geographic location and distribution of living organisms. It supports evolution in many ways because organisms are not distributed evenly throughout the world, but related organisms are found in the same isolated parts of the world ... and this is not explained by climate.
compare layers of sediment from different parts of the world, the sequence from the very earliest life to the present can be observed, and in this way the fossil record shows a change from simple to complex which supports the theory of evolution. For example it shows that invertebrates came before vertebrates.
What are vestigial organs?
Vestigial organs are remnants of structures that served important functions in the organism?s ancestors
What is Linnaean classification?
system of classification that emphasized the shared similarities of organisms.
List the levels included in Linnaean classification.
domain, kingdom, phylum, class, order, family, genus, and species
Explain how a cladogram is constructed.
Cladograms are constructed by grouping organisms together based on their shared derived
What happens during a chemical reaction?
one or more new compounds are formed as a result of the rearrangement of atoms.
Why is the law of conservation of energy important in chemical reactions?
states that matter is neither lost nor gained in traditional chemical reactions; it simply changes form. Thus, if we have a certain number of atoms of an element on the left side of an equation, we have to have the same number on the right side. This implies that mass is also conserved during a chemical reaction
Give an example of an acid-base reaction and an oxidation-reduction reaction.
Acid?base reactions are responsible for the sharp taste of a cola drink and the digestion of food in your stomach, as well as the formation and removal of atmospheric carbon dioxide. Oxidation?reduction reactions involve the transfer of one or more electrons from one reactant to another. Oxidation?reduction reactions underlie the workings of batteries, fuel cells, and the creation of energy from food in animals and are also responsible for the corrosion of metals and combustion of nonmetallic materials such as wood.
concentration of reactants:
One effective way to increase the rate of collisions is to increase the concentration of reactants. The reason is simply that, with higher concentrations, there are more molecules in a given volume, which makes collisions more probable
Higher temperatures tend to increase reaction rates. The reason is that the higher the temperature of a material, the faster its molecules are moving, and the more orceful the collisions between them so the more likely that these collisions will break bonds within reactant molecules.
the addition of a catalyst:
a substance that increases the rate of a chemical reaction by lowering its activation energy. The catalyst may participate as a reactant but it is then regenerated as a product and is thus available to catalyze subsequent reactions.
How can the addition of Sunlight affect chemical reactions?
The energy required to break bonds sometimes comes from the absorption of electromagnetic radiation. As the radiation is absorbed by reactant molecules, atoms in the molecules may start to vibrate with so much energy that the bonds between them are easily broken. For example, the common atmospheric pollutant nitrogen dioxide, NO2, may transform to nitrogen monoxide and atomic oxygen merely upon exposure to sunlight.
How do enzymes speed up chemical reactions in cells?
they lower what is called the activation energy of a chemical transformation
What are the reactants and products in photosynthesis?
The reactants of photosynthesis are sun light, carbon dioxide, and water. The products of photosynthesis are glucose, Oxygen, lipids, amino acids, monosaccharides, disaccharides, polysaccharides (organic molecules)
Why is light needed in photosynthesis?
a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight
Explain how the light dependent and light independent reactions produce the products of photosynthesis.
The light-dependent reactions involved photolysis, or the splitting of water by light to produce O2.? The light-independent reactions involved fixing CO2 to hydrogen to produce glucose.
What happens during the Calvin cycle?
During photosynthesis, light energy is used in generating chemical free energy, stored in glucose. The light-independent Calvin cycle, also known as the "dark reaction" or "dark stage," uses the energy from short-lived electronically-excited carriers to convert carbon dioxide and water into organic compounds that can be used by the organism (and by animals that feed on it). This set of reactions is also called carbon fixation.
What are the reactants and products for cellular respiration?
The reactants are the materials needed for the process: glucose and oxygen. The products are the materials produced during the process: carbon dioxide and water.
During the Krebs cycle, acetyl-CoA is broken down to carbon dioxide. Two molecules of ATP are harvested, and additional energy is stored in two other molecules, NADH and FADH2.
electrons carried by NADH and FADH2 are sent down electron transport chains. As electrons are passed from one carrier in the transport chain to the next, they lose energy. The energy released is used to pump hydrogen ions ( ) across a membrane inside the mitochondria. At the end of the electron transport chain, the electrons combine with an oxygen molecule to generate water.
Why is cellular respiration aerobic?
Cellular respiration refers to the biochemical pathway by which cells release energy from the chemical bonds of food molecules and provide that energy for the essential processes of life. It is aerobic because of the presence of Oxygen in breakdown of glucose
What happens when oxygen is not present in a cell?
Cells cannot break down glucose molecule to produce ATP.
Explain the role of the electron transport chain in photosynthesis and respiration.
electrons are transferred from a high-energy electron donor (e.g., NADH) to an electron acceptor (e.g., O2) through an electron transport chain. In photophosphorylation, the energy of sunlight is used to create a high-energy electron donor and an electron acceptor. Electrons are then transferred from the donor to the acceptor through another electron transport chain. Electron transport chains are used for extracting energy from sunlight (photosynthesis) and from redox reactions such as the oxidation of sugars (respiration).
Identify the cell organelles needed for photosynthesis and respiration.
Chloroplasts and mitochondria
Describe the characteristics of organisms.
They all use Energy, Another characteristic of living things is that they develop and grow Living things maintain themselves. They generate structures, such as stems and leaves or skin and bones, and they repair damage done to those structures, Living things also maintain their internal environment, keeping it stable in the face of changing external conditions, Living things have the capacity to reproduce, Finally, living things are parts of populations that evolve. Populations do not remain constant from one generation to the next but change over time, across generations.
Explain the size, structure, and characteristics prokaryotic cells and eukaryotic cells.
Prokaryotes are single-celled organisms and are very small, ranging from about 0.1 to 10 micrometers ( meter) in diameter. Their structure is considerably simpler than that of eukaryotes. The DNA of prokaryotes is found in a single circular structure called a chromosome and is not contained within a nucleus. Most prokaryotes have an outer cell wall that helps protect the cell. The prokaryote Escherichia coli, an occupant of the human digestive tract and one of the best-studied organisms in the world, is shown in Figure 15.8. Eukaryotes can be single-celled, like prokaryotes, or they can be composed of many cells. The fungus known as baker?s yeast, commonly used in baking and brewing, is a single-celled eukaryote (Figure 15.9). Plants, animals, and most other fungi are multicellular eukaryotes. Eukaryotic cells have their DNA in a distinct nucleus, a feature that distinguishes them from prokaryotes. In addition, the DNA of eukaryotic cells is found in linear, rather than circular, chromosomes. Eukaryotic cells also have numerous organelles, structures that perform specific functions for the cell. Finally, eukaryotic cells are larger than prokaryotic cells?where prokaryotic cells measure 0.1 to 10 micrometers, eukaryotic cells generally measure 10 to 100 micrometers.
Which structures are the same in prokaryotic and eukaryotic cells?
They perform most of the same kinds of functions, and in the same ways. Both are enclosed by plasma membranes, filled with cytoplasm, and loaded with small structures called ribosomes. Both have DNA which carries the archived instructions for operating the cell. And the similarities go far beyond the visible--physiologically they are very similar in many ways. For example, the DNA in the two cell types is precisely the same kind of DNA, and the genetic code for a prokaryotic cell is exactly the same genetic code used in eukaryotic cells.
How do plant cells differ from animal cells?
One of the primary differences between animal and plant cells is that plant cells have a cell wall made up of cellulose. This helps the plant cells to allow high pressure to build inside of it, without bursting. A plant cell has to be able to accept large amounts of liquid through osmosis, without being destroyed. An animal cell does not have this cell wall. If you start to fill the animal cell with too much distilled water or other fluid, it will eventually pop. Plant cells also are different from animal cells because they use photosynthesis to covert sunlight into needed food for the plant. Plant cells have chloroplasts, which has its own DNA, essentially directing the work of the chloroplasts.
the spread of particles through random motion from regions of higher concentration to regions of lower concentration.
the movement of water molecules through a selectively-permeable membrane down a water potential gradient
the movement of a substance against its concentration gradient (from low to high concentration).
In endocytosis, a portion of the cell membrane folds inward and pinches off, enclosing material within a vesicle inside the cell. Endocytosis is used by some white blood cells of the human immune system to engulf invading bacteria
In exocytosis, the opposite process occurs?a vesicle fuses its membrane with the cell membrane and dumps its contents outside the cell. Exocytosis in used by certain endocrine cells to release hormones into the bloodstream. Neurotransmitters? the chemicals that neurons use to signal one another?are also released through exocytosis
Describe the stages of mitosis.
During mitosis, the nucleus divides in four phases?prophase, metaphase, anaphase, and telophase. During prophase, the chromosomes condense, the nuclear membranes break down, and the mitotic spindle forms. During metaphase, the chromosomes line up along the equatorial plane of the cell. During anaphase, the two sister chromatids are pulled apart and move to opposite poles of the cell. During telophase, new nuclear membranes form around each set of chromosomes, and the chromosomes return to their loosely packed state.
What is the end result of mitosis?
cytokinesis, the division of the cytoplasm to yield two separate daughter cells.
What are the roles of cell division?
Cell division is normally a carefully orchestrated process controlled by a large number of genes.
List the events that occur during mitosis.
During mitosis, the nucleus divides in four phases?prophase, metaphase, anaphase, and telophase. During prophase, the chromosomes condense, the nuclear membranes break down, and the mitotic spindle forms. During metaphase, the chromosomes line up along the equatorial plane of the cell. During anaphase, the two sister chromatids are pulled apart and move to opposite poles of the cell. During telophase, new nuclear membranes form around each set of chromosomes, and the chromosomes return to their loosely packed state
List the events that occur during meiosis.
Interphase: Before meiosis begins, genetic material is duplicated. First division of meiosis, Prophase 1: Duplicated chromatin condenses. Each chromosome consists of two, closely associated sister chromatids. Crossing-over can occur during the latter part of this stage, Metaphase 1: Homologous chromosomes align at the equatorial plate, Anaphase 1: Homologous pairs separate with sister chromatids remaining together, Telophase 1: Two daughter cells are formed with each daughter containing only one chromosome of the homologous pair, Second division of meiosis: Gamete formation, Prophase 2: DNA does not replicate, Metaphase 2: Chromosomes align at the equatorial plate, Anaphase 2: Centromeres divide and sister chromatids migrate separately to each pole, Telophase 2: Cell division is complete. Four haploid daughter cells are obtained.
How does meiosis contribute to variation in offspring?
Meiosis produces great genetic diversity among an organism?s sex cells for two reasons. To see how, let?s consider the eggs produced by a human female. Like all humans, this woman has two of each kind of chromosome, one that she inherited from her mother and one that she inherited from her father. First, as we have seen, crossing over during meiosis I causes the woman?s homologous chromosomes to exchange parts, so that most of the chromosomes in her eggs are unique composites of the chromosome she inherited from her mother and the chromosome she inherited from her father. Even if there were no such thing as crossing over, however, the woman would still produce a huge number of genetically different eggs. This is because each pair of homologous chromosomes separates independently during meiosis I. If we ignore crossing over, each egg would receive either the chromosome the woman inherited from her mother or the chromosome she inherited from her father. One egg could receive chromosomes 1, 3, 4, 5, 7, 10, 13, etc., from her mother and chromosomes 2, 6, 8, 9, 11, 12, etc., from her father. A second egg she produces is almost certain to receive a different set of chromosomes, perhaps chromosomes 2, 3, 5, 6, 7, etc., from her mother and chromosomes 1, 4, 8, 9, etc., from her father. It is clear that the independent separation of homologous chromosomes alone produces a huge number of possible egg cells. Crossing over only expands the possibilities. It?s no wonder that no two eggs or sperm produced by a single individual are alike. This genetic diversity produced during meiosis is crucial to evolution.
Explain how crossing over promotes genetic variation.
Crossing over is the exchange of corresponding alleles at the same locus between non- sister chromatids in homologous chromosome pairs at metaphase 1 in meiosis. This shuffles the alleles and produces new combinations of alleles in the gametes produced.
Describe the patterns Mendel observed when he experimented with pea plants.
Mendel showed that the inheritance of traits follows particular laws, which were later named after him. The significance of Mendel's work was not recognized until the turn of the 20th century. Its rediscovery prompted the foundation of genetics.
the principle of segregation:
during the formation of reproductive cells (gametes), pairs of hereditary factors (genes) for a specific trait separate so that offspring receive one factor from each parent.
the principle of independent assortment:
determines which factor for a particular trait is inherited. Mendel's third law (also called the law of dominance) states that one of the factors for a pair of inherited traits will be dominant and the other recessive, unless both factors are recessive.
are chromosome pairs of the same length, centromere position, and staining pattern, with genes for the same characteristics at corresponding loci. One homologous chromosome is inherited from the organism's mother; the other from the organism's father.
What causes genetic mutations?
CA genetic mutation occurs when the sequence of nucleotides?the A, C, G, T sequence?in an organism?s DNA is changed. Genetic mutations may result from errors during DNA replication or from exposure to mutagens (mutationcausing agents) such as ultraviolet light, X-rays, chemicals, and even some products that occur naturally when we break down organic molecules to obtain energy.
What factors determine the effect of a genetic mutation?
Genetic mutations can have no effect at all or they can have very dramatic effects. The effect a mutation has depends on several factors, including where in the genome a mutation occurs, which cells are affected, and the nature of the mutation itself. Mutations that strike ?junk? DNA or introns are likely to have less impact than mutations affecting protein-coding sequences. Mutations in egg or sperm cells are particularly significant in that they can be passed to offspring, where they will occur in every cell in the body.
Describe the different types of mutations and how each type affects the production of protein and traits.
Mutations come in several forms?a nucleotide can be substituted with a different nucleotide, or nucleotides can be inserted into the genome or deleted from it. A point mutation occurs when one nucleotide is substituted for another. Point mutations sometimes change the sequence of amino acids in a protein. For example, a mutation from AAC to AAG would replace asparagine with lysine. Not all point mutations affect amino acids, however?a mutation from GCA to GCC would have no effect because both codons code for alanine. In addition, for proteins that function as enzymes, the lock-and-key fit of enzyme to substrate (Chapter 15) can potentially be disrupted by a single change in the enzyme?s amino acid sequence. One kind of point mutation that almost always affects protein function is the nonsense mutation, which creates a stop codon in the middle of a protein- coding sequence. Nonsense mutations result in the production of shorter, often nonfunctional, proteins. If nucleotides are added to or removed from a protein-coding sequence, the triplet codons that are ?read? and translated will be shifted, completely altering the sequence of amino acids. This is known as a frameshift mutation. Frameshift mutations also tend to have significant disruptive effects on proteins.
How does ionizing radiation from radioactive materials damage the DNA?
Radioactive materials release ionizing radiation?gamma rays, beta particles, and alpha particles. When these forms of radiation strike electrons in the body with enough energy, they free the electrons from the atoms they were orbiting. The free electrons can then strike and damage DNA directly.
Why are bone marrow cells, hair cells, and cells in the gastrointestinal tract more vulnerable to radiation damage?
Cells have the capacity to repair some of the damage done to their DNA, but they vary in their ability to do so. In particular, cells in the body that divide frequently have less time to repair DNA damage before that DNA is replicated and mutations are passed on.
Why do ultraviolet radiation and radon cause cancer?
Exposure to UV light can impair a cell?s ability to undergo programmed cell death when it is damaged. (It is this programmed death that causes skin to peel after a sunburn.) Without this ability, damaged cells survive, their DNA continues to accumulate mutations, and they ultimately give rise to cancer. Reducing sun exposure and making proper use of sunscreens are important for
hair, blood, saliva, and other bodily products they can find in order to look for the genetic version of fingerprints
Single nucleotide polymorphisms (SNPs):
study of single-nucleotide polymorphisms is important in crop and livestock breeding programs , in biomedical research is for comparing regions of the genome between cohorts (such as with matched cohorts with and without a disease).
the direct human manipulation of an organism's genetic material in a way that does not occur under natural conditions. It involves the use of recombinant DNA techniques, but does not include traditional animal and plant breeding or mutagenesis.
Polymerase chain reaction (PCR):
a scientific technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence. The method relies on thermal cycling, consisting of cycles of repeated heating and cooling of the reaction for DNA melting and enzymatic replication of the DNA. Primers (short DNA fragments) containing sequences complementary to the target region along with a DNA polymerase (after which the method is named) are key components to enable selective and repeated amplification.
in Plant Biotechnology, commercial forestry, vaccine against bacterial pneumonia, molecular cloning in biotechnology and research.
Recombinant restriction enzymes:
a technique that allows nucleotide sequences from two different species to be combined within a single organism.
the insertion, alteration, or removal of genes within an individual's cells and biological tissues to treat disease.
Preimplantation genetic diagnosis (PGD) is a genetic procedure used prior to implantation to help identify genetic defects within an embryo created through in vitro fertilization and to prevent certain diseases or disorders from being passed on to the child. In most cases, the female, the male, or both have been genetically screened and determined to be carriers.
Restriction fragment length polymorphisms (RFLPs):
Most frequently, forensic scientists use restriction fragment-length polymorphisms?RFLPs?to match DNA evidence to suspects. What are RFLPs? Many bacteria have enzymes known as restriction enzymes. Restriction enzymes cut DNA wherever they find a specific sequence of nucleotides.
Recombinant DNA technology:
a technique that allows nucleotide sequences from two different species to be combined within a single organism.
the process of producing similar populations of genetically identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually. Cloning in biotechnology refers to processes used to create copies of DNA fragments (molecular cloning), cells (cell cloning), or organisms.
found in all multi cellular organisms. They are characterized by the ability to renew themselves through mitotic cell division and differentiate into a diverse range of specialized cell types.
Describe how cells, tissues, organs, and organ systems work together to perform human body functions.
Multiple cells make up a tissue, a group of similar cells that performs a certain function. Skin and muscle are examples of tissues. Multiple tissues combine to make an organ, a structure in the body that has a certain function. The heart, stomach, ovaries, and brain are all organs. Finally, multiple organs make up an organ system that is responsible for performing particular bodily functions. The digestive system, consisting of the mouth, esophagus, stomach, small and large intestines, as well as the pancreas and liver, is an organ system that is responsible for processing the food we eat. In fact, the human body functions through ten major organ systems?nervous, endocrine, reproductive, sensory, muscular and skeletal, circulatory, respiratory, digestive, excretory, and immune.
How does our body maintain homeostasis?
Our body maintains Homeostasis by responding to the outside environment and maintaining the stable internal environment. If we feel cold, we may pile on more clothes, or wrap our arms around our bodies to reduce heat loss or shiver to generate heat. On the other hand, when it?s hot outside, we take off our clothes; look for shade, and sweat to cool off. Also, more blood goes to the extremities and to the face, which are good at shedding heat. (This explains why our faces get red when we?re hot.) Oxygen supply and body temperature are only two of the many variables the body carefully maintains. The amount of water in the body, the concentration of nutrients such as glucose and of waste products in the blood, the concentrations of important ions inside and outside cells, and blood pH?all these variables are carefully controlled as part of maintaining homeostasis.
Explain how the neurons, spinal cord, and brain work together to respond to stimuli.
The sense of touch is actually several different senses, telling us about stimuli as diverse as pressure, temperature, and pain. Pressure, like hearing, causes the ?hairs? on sensory cells to bend, opening ion channels and starting action potentials. We have separate sensory cells for detecting light touch and heavy pressure. Temperature sensing relies on cells with ion channels that are directly affected by temperature. Some temperature-sensing cells respond to cold, others to warmth. Interestingly, chemical menthol (found in peppermint) also stimulates cold receptors? it is this coincidence, not an actual cold temperature, which brings on the cool feeling you get from eating a mint. Pain receptors respond to stimuli that cause damage to the body. These sensory cells generally require strong stimulation before they will respond. However, damaged tissues release chemicals called prostaglandins that increase the sensitivity of pain receptors. (Aspirin, you may recall, provides pain relief by interfering with the production of prostaglandins (Chapter 15)). Also, whereas most sensory cells become less sensitive with repeated stimulation?this is why you stop noticing the funny smells in your house, or feeling the weight of your backpack?pain receptors actually become more sensitive with continued stimulation. Some types of chronic pain may in fact result from pain receptors that have become abnormally sensitive.
Explain the functions of the cells, heart, arteries, and veins of the circulatory system in transporting oxygen and carbon dioxide throughout the body
Blood leaves the left side of the heart and travels through arteries which gradually divide into capillaries. The blood then travels in veins back to the right side of the heart, where it is pumped directly to the lungs. In the lungs, carbon dioxide is exchanged for oxygen, and this renewed blood flows back to the left side of the heart, and the whole process begins again. The majors parts of the circulatory system are the heart, arteries and veins. The heart pumps blood to the arteries. The arteries take the oxygenated blood to the muscles. The veins take blood back to the heart, which then releases carbon dioxide in the lungs
Describe how the cells, tissues, and organs associated with the digestive system break down food.
At the bottom of the esophagus, chewed food moves through a sphincter, or ring-shaped muscle, into the stomach., release gastric juice, a highly acidic mix of hydrochloric acid, digestive enzymes, and a protective mucus that prevents the stomach from digesting its own tissues. When we vomit, the acidic nature of our stomach contents becomes immediately apparent both from the taste and from the burning sensation in our throats. The purpose of this acidity is to kill any bacteria we swallow with our food. In the stomach, digestive enzymes and a muscular churning action combine to reduce our food to a thick liquid called chyme. Chyme exits the stomach through a second sphincter and enters the small intestine. Typically, it takes the stomach about 4 hours to process a meal. The small intestine is about 20 feet long. In the duodenum, the first foot of the small intestine, digestion continues with the breakdown of proteins, fats, carbohydrates, and nucleic acids. Some of the digestive enzymes at work in the duodenum are made by the small intestine itself. Others are made by the pancreas. Pancreatic enzymes play an important role in neutralizing food, which arrives from the stomach in a highly acidic condition. In addition, the small intestine receives bile, a substance that is produced in the liver and stored in the gall bladder. Bile is an emulsifier?it breaks fats into tiny droplets that are more easily attacked by enzymes. Beyond the duodenum, the rest of the small intestine functions primarily in absorbing nutrients into the body. In order to be able to do this efficiently?that is, rapidly?the small intestine has a huge surface area. It is covered with numerous fingerlike projections called villi, each of which is in turn covered with tiny little projections called microvilli. Flattened, the small intestine would fill the area of a tennis court! Digested nutrients are absorbed across the surface of the small intestine into capillaries found inside each villus. Absorption of most types of molecules occurs through facilitated diffusion or active transport . After nutrient absorption, what?s left of our food moves into the large intestine. In the large intestine, water and minerals such as sodium are absorbed into the body. The large intestine is also home to large numbers of Escherichia coli and other bacteria, which feed off our undigested materials. Some of these bacteria are useful to us because they synthesize vitamins, notably vitamin K and some of the B vitamins, which we absorb and use. From the large intestine, feces are eliminated from the body through the anus. Feces are composed primarily of living and dead bacteria and undigestible materials such as plant cellulose.
Describe how the cells, tissues, and organs in the urinary system aid in eliminating waste from the body and maintaining water balance.
Excretion begins in the kidneys. The functional unit of a kidney is called a nephron. Our kidneys contain about a million nephrons apiece. From the circulatory system, fluid enters the nephron through a cupshaped structure known as Bowman?s capsule. It then flows through the rest of the nephron, moving through the proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct. What enters the nephron is more or less blood plasma, and what comes out is urine. Let?s look at how this happens. Each nephron in our kidneys is associated with a cluster of capillaries called the glomerulus. The glomerulus is surrounded by a cup-shaped structure called Bowman?s capsule. Blood pressure in the glomerulus pushes fluid out of the capillaries and into Bowman?s capsule. This fluid is called the filtrate and is pretty similar to blood plasma. From Bowman?s capsule, the filtrate flows into the proximal convoluted tubule. The proximal convoluted tubule acts like a sorting machine. In it, some ?good? molecules in the filtrate?including many ions, as well as glucose, vitamins, and amino acids?are transported back into the blood to be kept by the body. Also, additional waste molecules are transported from the blood into the filtrate. This movement of molecules in and out of the filtrate occurs through active transport (Chapter 15), one of the reasons why excretion consumes a considerable amount of energy. After moving through the proximal convoluted tubule, the filtrate continues into the loop of Henle, a hairpin-shaped loop. The loop of Henle functions in reabsorbing water from the filtrate. It does this by resting in a solute concentration gradient from one end of the loop to the other. Specifically, there is low solute concentration near the ?ends? at the top of the hairpin and high solute concentration near the loop at the bottom of the hairpin (Figure 20.20). As the filtrate flows down the descending branch of the loop of Henle, it encounters the zone of high solute concentration. Water moves from the filtrate to the surrounding tissues via osmosis (Chapter 15), making the filtrate much more concentrated than before. Then the filtrate moves up the ascending branch of the loop of Henle. Water does not flow back into the filtrate as it moves through the low-solute part of the loop of Henle because the walls of the ascending branch simply aren?t permeable to water. However, as the filtrate moves up the ascending branch, more ions are pumped out of it through active transport, so that the filtrate is once again less concentrated than the high solute concentration zone. We will see why this is important in a moment. After ascending the loop of Henle, the filtrate moves into the distal convoluted tubule, where additional wastes are transported into it. Finally, the filtrate moves down the collecting duct where more water may be reabsorbed.
Explain the role of cells, tissues, and organs in the acquired immune response.
The acquired immune system is very specific in its response to pathogens and other foreign substances. Each cell of the acquired immune system has receptors that respond to a single antigen?a molecule or part of a molecule belonging to a foreign pathogen. Most often, antigens are parts of foreign proteins. The acquired immune response is much slower than that of the innate immune system, usually taking between 3 and 5 days to reach full force. In addition, the acquired immune system retains a ?memory? of pathogens it has encountered in the past, so that subsequent responses to the same pathogen can be faster and more aggressive. The acquired immune system includes a tremendous number of different receptors?on the order of 10 million. This makes it very likely that any foreign pathogen, whether it is a bacterium, a virus, or a worm, will trigger a response by one or more acquired immune cells.
Chemistry and Biology
Biology deals with living material, chemistry with dead material that has not been alive. Themes in biology range from animals and plants to microorganisms and viruses. Since living things use the same chemical principles as a chemist (but not always the same conditions) they deal with lot of the same processes. The field of chemistry in living material is correctly called Biochemistry and this is somewhere in between Biology and Chemistry. So when looking what is happening inside a cell, it is no longer clear whether this is Biology or Chemistry. It is Natural Sciences.
Physics and Chemistry
Examples include error analysis and statistics, molecular collisions and the gas laws, wave interference and the analysis of crystal structure, and the Bohr model and the periodic table. Although the study of atomic orbitals in chemistry follows naturally from a treatment of the Bohr atom in physics, the treatment of the Bohr model must be done at the sacrifice of more traditional topics in basic physics. On the other hand, wave optics and the analysis of crystal structure using diffraction techniques are very natural topics for integration. Indirectly, physics and chemistry integration also occurs through engineering projects such as designing a natural gas storage tank for vehicles. Statistical distributions and molecular collisions are natural topics for physics and chemistry integration.
Physics and Astronomy
Examples are the physical principles of atmospheric phenomena; composition and structure of the atmosphere, energy flows, and the resulting air motions and weather from small to planetary scales. Physics and astronomy continues to expand with a growing body of research leading to discoveries such as the Standard Model of Fundamental Particles and a detailed history of the universe, along with revolutionary new technologies like nuclear weapons and semiconductors. This interdisciplinary field includes astrophysics and cosmology, atomic and molecular physics, mathematical and theoretical physics, nuclear physics, engineering and optical engineering.
Earth Science and Physics
Earth science is an all-embracing term for the sciences related to the planet Earth. The integration of Earth science and Physics is the application of physics to the study of the atmosphere. Atmospheric physicists attempt to model Earth's atmosphere and the atmospheres of the other planets using fluid flow equations, chemical models, radiation balancing, and energy transfer processes in the atmosphere (as well as how these tie in to other systems such as the oceans). In order to model weather systems, atmospheric physicists employ elements of scattering theory, wave propagation models, cloud physics, statistical mechanics and spatial statistics which are highly mathematical and related to physics. It has close links to meteorology and climatology and also covers the design and construction of instruments for studying the atmosphere and the interpretation of the data they provide, including remote sensing instruments. At the dawn of the space age and the introduction of sounding rockets, aeronomy became a sub discipline concerning the upper layers of the atmosphere, where dissociation and ionization are important.
Earth Science and Chemistry
Earth science is an all-embracing term for the sciences related to the planet Earth. The integration of Earth science and chemistry is the chemical composition of the Earth and other planets, chemical processes and reactions that govern the composition of rocks and soils, and the cycles of matter and energy that transport the Earth's chemical components in time and space, and their interaction with the hydrosphere and the atmosphere..
Astronomy and Physics
Examples are the physical principles of atmospheric phenomena; composition and structure of the atmosphere, energy flows, and the resulting air motions and weather from small to planetary scales. Physics and astronomy continues to expand with a growing body of research leading to discoveries such as the Standard Model of Fundamental Particles and a detailed history of the universe, along with revolutionary new technologies like nuclear weapons and semiconductors. This interdisciplinary field includes astrophysics and cosmology, atomic and molecular physics, mathematical and theoretical physics, nuclear physics, engineering and optical engineering.
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