How can we help?

You can also find more resources in our Help Center.


Investigations are conducted to
Identify potential problems and to create solutions to those problems before they actually occur
An explanation formulated to answer the questions being investigated; A statement that can be tested
Steps of Forming a Hypothesis
1. Identify the problem-Observe and determine the problem to be investigated

2. Ask questions-Ask questions and attempt to formulate a solution to the problem

3. Formulate a Hypothesis-Formulate explanations to answer the questions. This involves making predictions that follow from the initial statement of the problem. Is not subject to interpretation.
If no reasonable test can be designed..
it becomes necessary to reformulate the hypothesis. It is of little value to quantitatively pursue the validity of a statement without any ability to measure an outcome.
Scientific Method
1. Problem identification
2. Question asking
3. Hypothesis development
4. Data collection and experimentation
5. Analysis
6. Conclusion
Data Collection
Collect data throughout the scientific process to test the hypotheses or predictions in a controlled environment.
4 Main Steps of Data Collection
1. Observation
2. Measurement
3. Samples
4. Organization
Scientists use the 5 senses to learn as much as possible during data collection.
Direct-such as listening to a bird call
Indirect-such as observing qualities of planets
Allows for collection of quantitative data
Data typically cannot be collected from every member of a population. Collect information from a representative sample of the population. Obtain data from a subset of the population that looks like the population, but is small and more manageable.
Data should be organized. May involve placing informatin in tables and/or charts.
Involves comparing a control group and an experimental group. Both groups are compared to understand what effect the variable has on the experimental group.
Must analyze data collected during experimentation. The researchers must determine if the data is reliable (consistent with past results) and whether or not it supports the hypothesis.
Scientists produce models to represent the explanations supported by the data.
A way of drawing conclusions without direct observatioin
Broad statement of what is thought to be true; A theory that is thought to be true may be proven incorrect when technology enables better data collection
Mathematics in Science Research
Data is recorded in numerical form.
Data are then related to one another through the relationships established by graphs and empirical formulas.
No modern conveniences could exist without math because the creation of all technology is ultimately mathematical.
If mathematics was not used..
the best scientific descriptions would be purely qualitative in nature.
Quantitative Investigations
Uses numerical information (or data)
Data management
through the use of software programs improves the efficiency of an investigation
Scientific explanations (or models)
Direct results of the evidence that currently supports them
As improvements are made, collection of new data often leads to more refined alternative explanations
Measuring and observational devices have been developed so that smaller increments of time and length have become accessible
Deductive reasoning
A method whereby conclusions follow from general principles; Leads to a specific conclusion; General to Specific
Inductive reasoning
A method of arriving at general principles from specific facts; Specific to General
Study of the structure of organs and body systems
Study of the function of the organs and body systems
Smallest parts of elements that still retain all the original properties of the element
Atoms combine to form this
Specific molecules combine to form this
is the basic unit of all life
Cells combine in terms of function and type to form this
Organ Level
Two or more tissue types work together to perform a specific function; Possible to perform extremely complex functions
Organ System
When organs work together to perform a task
How many organ systems are there in the human body?
11 organ systems
Result of all organ systems working together within the body
Hierarchy of the Structure of the Human Body
Bottom to Top:
Organ Systems
4 Tissue Types
Epithelial, Connective, Muscular, and Nervous
Epithelial Tissue Functions
It can provide covering or produce secretions
Epithelial Tissue
Exists in sheets and does NOT have its own blood supply.
Simple Epithelium
One layer of cells. Is found in body structures where absorption, secretion, and filtration occur.
Stratified Epithelium
Has more than one layer of cells. It serves as protection
Shapes of Epithelial Cells
Squamous, Cuboidal, Columnar
Connective Tissue
Found throughout the body; It serves to connect different structures of the body; Has its own blood supply
Types of Connective Tissue
Bone, Cartilage, Adipose (Fat), and Blood Vessel, Ligaments
Muscle Tissue
Produces movement.
Three Types of Muscle Tissue
Skeletal, Cardiac, Smooth
Skeletal Muscle
Supports voluntary movement since it is connected to bones in the skeletal system
Voluntary Movements
Consciously controlled by the brain
Smooth Muscle
Involuntary control; Found in the walls of hollow organs, such as intestines, blood vessels, bladder, and uterus
Involutary Movements
Cannot be consciously controlled
Cardiac Muscle
Found only in the heart
Nervous Tissue
Provides structure for the brain, spinal cord, and nerves
Made up of specialized cells called neurons
Send electrical impulses throughout the body
Support Cells
Help protect nervous tissue
ex. Myelin
Circulatory System
also called the Cardiovascular System
Consists of the heart, blood vessels, and blood
Supports the circulation and distribution of various substances throughout the body
Oxygen, hormones, and nutrients from food are some of these substances
Digestive System
Consists of all the organs from the mouth to the anus involved in ingestion and breakdown of food
Organs include the esophagus, stomach, small and large intestines, rectum, and anus
Makes enzymes that break down food
Any food that is not digested is expelled through the anus
Absorption of nutrients occurs in the small intestine
Small Intestine
Absorption of nutrients
Consists of duodenum, jejunum, and ileum
Removes water from the waste
Produces bile that helps break down fats
Delivers enzymes to the small intestine that aid in digestion
Urinary System
Also called the excretory system
Helps maintain the water and electrolyte balance, regulates the acid-base balance of the blood, and removes all nitrogen-containing wastes from the body
Helps regulate blood volume and pressure by adjusting urine volume
Activates vitamin D
Nervous System
Controls the blood pressure, heart rate, and distribution of blood
Consists of the brain, spinal cord, and nerves
Serves as body's control system
Integumentary System
Allows heat to escape by dilating blood vessels
Blood Cells are formed in the
Marrow of the bones in the skeletal system
Endocrine System
Glands secrete hormones that regulate growth and the release of calcium
Integumentary System
Consists of the skin, mucous membranes, hair, and nails
Also serves as a barrier to pathogens
Lymphatic System
Consists of lymph nodes, lymph vessels that carry lymph, the spleen, the thymus, and tonsils
Supports the immune system
Transports sex hormones
Muscular System
Consists of skeletal muscles, tendons that connect muscles to bones, and ligaments that attach bones together to form joints
Cardiac and Smooth muscles are not included here
Reproductive System
Main purpose is to produce offspring
Consists of the testes, penis, ovaries, vagina, and breasts
Respiratory System
Keep's the body's cells supplied with oxygen and removes carbon dioxide as it is released from cells
Consists of the nasal cavity, pharynx, larynx, trachea, bronchi, and lungs
Provides for air exchange and supplies tissues with oxygenated blood
House tiny air sacs called alveoli
Through these walls, the oxygen and carbon dioxide move in and out of the lungs via small blood vessels called arterioles
Skeletal System
Provides support and protection for the body and its organs
Creates movement
Consists of bones, cartilage, ligaments, and joints
Storage for minerals such as calcium and phosphorus
Anatomical Position
Body facing forward, feet are parallel to each other, arms are at he sides with the palms facing forward
Toward the upper end of the body or body structure
Toward the lower end of the body or body structure
Toward the front of the body or body structure
Toward the back of the body or body structure
Toward the middle of the body or body structure
Toward the outer sides of the body or body structure
Between medial and lateral
Close to the origin of the body part or point of attachment
Away from the origin of the body part or point of attachment
Toward or at the body surface
Away from or below the body surface
Sagittal Section
Cut made along a longitudinal plane dividing the body into right and left parts
Midsagittal Section
Sagittal section made down the median of the body
Transverse Section
Cut made along a horizontal plane to divide the body into upper and lower regions
Frontal Section
Cut made along a longitudinal plane that divides the body into front and back regions
Dorsal Body Cavity
Contains the cranial cavity and spinal column
Ventral Body Cavity
Contains all the structures within the chest and abdomen
Divides the ventral cavity into the thoracic cavity
Abdominal and Pelvic Cavities
Below the diaphragm
Receive, interpret, and respond to internal and external stimuli via the nervous system
Transport oxygen and other nutrients to tissues via the cardiovascular system
Remove metabolic wastes from the body via the renal system
Allow voluntary and involuntary movement of body via the musculoskeletal and neurological systems
Take in and break down nutrients to be used for metabolism via the digestive system
Take in oxygen and expel carbon dioxide via the respiratory system
Hormonal control of body functions via the endocrine system
Production of offspring via the reproductive system
When all the needs of the body are met and all of the organ systems are working properly
Stable state
Where can Connective tissue be found in the human body?
Where can Epithelial tissue be found in the human body?
Where can Muscle tissue be found in the human body?
Where can Nervous tissue be found in the human body?
This system works as the transportation system for substances such as oxygen, carbon dioxide, and nutrients in the body
Circulatory System
This system breaks down food so that the nutrients can be easily passed into the blood and circulated throughout the body
Digestive System
This system controls body functions
Endocrine System
This system protects internal tissues from injury, waterproofs the body, and helps regulate body temperature, This system also serves as a barrier to foreign substances
Integumentary System
This system helps cleanse the blood and houses the white blood cells that are involved in protecting the body from environmental pathogens
Lymphatic System
This system produces movement through contraction
Muscular System
This system acts as the body's control system and is necessary to protect the body from changes in the internal and external environment
Nervous System
This system produces offspring
Reproductive System
This system keeps all the cells in the body supplied with oxygen and removes the carbon dioxide
Respiratory System
This system provides support and protection for the body, supplies a framework used to create movement, and serves as storage for minerals, such as calcium
Skeletal System
This system helps maintain the water and electrolyte balance within the body, regulates the acid-base balance in the blood, and removes all nitrogen-containing wastes from the body
Urinary System
Organ that contracts and pumps blood throughout the body
Blood vessels that transport blood away from the heart to the capillaries
Blood vessels that transport blood from the capillaries back to the heart
Tiny blood vessels that transport blood from arteries to veins within the body
Serve as the location for the exchange of oxygen, carbon dioxide, fluid, and nutrients within the body
Four Chambers in the Heart
Right and left atriums and the right and left ventricles
Four Valves in the Heart
Prevent flow of blood back into the heart's chambers after a contraction
Tricuspid and Pulmonary Valves
On the right side of the heart
Mitral and Aortic Valves
On the left side of the heart
Flow of Blood through the Heart
Deoxygenated blood enters into the heart through the superior and inferior vena cava
Blood travels into the right atrium and flows through the tricuspid valve into the right ventricle
Blood is pushed through the pulmonary valve into the pulmonary artery and lungs when the right ventrical contracts and picks up oxygen
Oxygenated blood is then carried back to the heart by the pulmonary veins into the left atrium through the mitral valve and into the left ventricle
Contraction of the left ventricle forces the blood through the aortic valve, through the aorta, and out to the entire body
Q: If the mitral valve is damaged, which problem may occur?
A: Backflow of blood into the left atrium
The mitral valve is on the left side of the heart, separating the ventricle and atrium
True or False: Blood that passes through the tricuspid valve enters the left ventricle
False. Blood that passes through the tricuspid valve enters the right ventricle
True or False: Blood that passes through the mitral valve enters the pulmonary artery
False. Blood that passes through the mitral valve enters the left ventricle
True or False: After contraction of the left ventricle, blood enters the aorta
True or False: After contraction of the right ventricle, blood enters the pulmonary artery
True or False: After contraction of the right atrium, blood enters the right ventricle
True or False: The pulmonary valve ensures that blood stays in the aorta
False. The pulmonary valve ensures that blood stays in the pulmonary artery
Primary function is breathing in oxygen and exhaling carbon dioxide
Act of taking in oxygenated air
When abdominal muscle contracts, pulls air into the lungs
Chest cavity enlarges, creating negative pressure in the chest cavity and pulls air into the lungs
Carbon dioxide is forced out of the body
When the diaphragm relaxes
The respiratory system supplies the body with _____ and removes _____
Oxygen, Carbon dioxide
It is through the walls of the _____ that oxygen and carbon dioxide move in and out of the capillaries in the lungs
Cranial Nervous System
Brain and Spinal Cord
Peripheral Nervous System
Cranial and spinal nerves that extend beyond the CNS
Divided into the automatic nervous system and the sensory-somatic nervous system
Autonomic Nervous System
Controls automatic body functions, like heartbeat and digestion
Includes both the sympathetic and parasympathetic nerves
Sympathetic Nerves
Are active when a person is excited or scared
Parasympathetic Nerves
Are active when a person is eating or at rest
Sensory-Somatic Nervous System
Consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves and associated ganglia
Controls voluntary actions like talking and walkin
Collections of nerve cell bodies
Receive stimuli from the internal and external environment and bring those stimuli to the neurons for interpretation
Specialized cells that make the nervous system and transmit messages
Connects one neuron with another neuron over a fluid filled gap called a synaps
Three Main Functions of the Nervous System
Provide sensory, motor and integrative functions within the body
Sensory Functions
Feeling pain, heat, and other stimuli
True or False: The nervous system directs bodily defenses against external stimuli
True or False: The nervous system regulates heart and breathing rates
True or False: The nervous system supplies the body with oxygen and removes carbon dioxide
False.This is a function of the respiratory system
True or False: The nervous system releases heat built up by the muscular system
False. This is a function of the integumentary system
Rhythmic contractions that propel food towards the colon and anus
Move food along the gastrointestinal tract as the food is mechanically and chemically broken down
Mixture of food, chemicals, and enzymes in the stomach
Colon (Large Intestine)
Absorption of water and storage and formation of feces
The digestion of carbohydrates begins in the _____
The propulsion of food through the gastrointestinal tract is called
The surface area for absorption in the small intestine is increased as a result of
Villi and microvilli.
Villi and Mircovilli
Finger-like projections of tissue in the intestines that significantly increase the surface area from which nutrients are absorbed
Immune System
Tissues, cells, and organs that fight off illness and disease
Produced by natural killer cells or NK cells
Target cancer and virus cells
Process of white blood cells squeezing through capillary slits in response to cytokines
Passive Immunity
An individual does not produce his or her own antibodies, but rather receives them directly from another source, such as mother to infant through breast milk
Active Immunity
An individual receives a vaccine that stimulates an actual infection by a pathogen, stimulating the body to produce antibodies for future protection
Cell-mediated Immunity
T cells are responsible for recognizing nonself cells
T cell
Lymphocyte that triggers the action of other lymphocytes
What kind of immunity is produced by a vaccine?
Artificially acquired active immunity
What is released by damaged cells in an effort to draw white blood cells to the area of damage?
What is the physiological benefit of a mild to moderate fever?
The warm body temperature that occurs, accelerates the destruction of pathogens and increases the activity of white blood cells
Fertility Rates
Average number of children a woman will have during her childbearing years which occur between the ages of 15 and 44
Replacement Rate
The number of births needed to maintain the population at its current number
Factors that affect birth and fertility rates
Religion, culture, economy, employment, government, education, literacy, infant mortality rates, abortions, and accessibility of family planning
Fertility rates are higher in which types of countries?
Fertility rates are higher in less-developed countries due to higher infant and child mortality rates
Crude Birth Rate
Number of births per 1,000 people per year
Crude Death Rate
Number of deaths per 1,000 people per year
Act of an individual moving into a region or country to live (migrate into)
Act of an individual moving out of one region or country to live in another (migrate out)
Changes in a Population are affected by the country's
Economy, politics, medical care, natural resources, food, land, water, and climate
Biological Classification System
Developed by biologists to name, organize, and categorize organisms
Eight Levels in Taxonomy Hierarchy
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Not capitalized
Charles Darwin
Was the first to study and write about species adaptation
Natural Selection
Occurs when some individuals of a species are better able to survive in their environment and reproduce than others
"Survival of the Fittest"
Responsible for heredity
Different forms of genes
Changes in the DNA that affect the way a gene functions
Permanent changes in DNA sequences
Some individuals of a species are better able to survive and adapt to the environment in which they live
Deoxyribonucleic Acid
Double helix
Ribonucleic Acid
Single Strand
Nucleic Acid
Store and transmit hereditary information
Nucleic Acid Structure
Chain of nucleotides that consists of a pentose, a phosphate group, and a nitrogenous base
Five types of Nitrogenous Bases
Adenine, Cytosine, Guanine, Thymine, Uracil
Two Rings
Adenine and Guanine
One Ring
Thymine and Cytosine
Cells copy the instructions in the DNA into RNA and send the messenger RNA to the ribosomes
Proteins are made by ribosomes from the information and sent out to the entire cell
True or False: RNA is the messenger between DNA and protein production
Prokaryotic Cells
Eubacteria and Archaebacteria
Cell Wall
Separate the inside and outside of the cell
Plasma Membrane
Semipermeable-allows certain substances in and out of the cell as needed
Tiny organs
Condensed DNA of the cell
Small, circular portions of DNA not associated with the nucleoid
Long and whip-like and project outward from the cell
Allow communication and transfer of information between two cells
Eukaryotic Cells
Not bacteria
Endoplasmic Reticulum
Stack of flattened membranous sacs
Two types: Rough and Smooth
Rough ER
Ribosomes on top, causing it to have a rough appearance
Golgi Apparatus
Involved in the packaging and transport of proteins in the cell
Small membrane-bounded sacs within the cytoplasm
Basic storage unit of the cell that can hold various compounds
Contains digestive enzymes that are capable of disposing of cellular debris and worn cellular parts
Rid the body of toxic components
Where ATP is produced
Act as tracks
Microtubule-organizing centers that help to form and organize the mitotic spindle during mitosis
Control center of the entire cell because it contains the cell's genetic material and directs all of the activities of the cell
Produce ribosomes that get moved to the cytoplasm to make cell proteins
More than Flagella
In plants
Nuclear Membrane
Encases the nucleus
In prokaryotic (bacterial) cells, the DNA is located in the
In eukaryotic (animal/plant) cell, the DNA is found in the
Chain of Amino Acids
Are large structures of DNA that contain the genes
Produces a more specialized cell from a less specialized cell
Determines what cell type each cell will become
An animal or plant in the early stages of development after fertilization
Fertilized egg
Individual tissue layers begin to form
Stem Cells
Cells divide and remain undifferentiated
Three types of stem cells
Totipotent, pluripotent, multipotent
Process of cell duplication in which two daughter cells receive exactly the same nuclear material as the original cell
Occurs to replace old and dying cells with genetically identical ones
S Phase
Synthesis of DNA
G₁ and G₂
Gap periods before and after synthesis
G₁, S phase, G₂
Cells that form a new organism via sexual reproduction
Gametes reduce their DNA content in half
Occurs only in gametes or fertilized eggs
Diploid Cells
Two sets of chromosomes
Haploid Cells
Single set of chromosomes
Homologous Chromosome
Identical chromosomes
Process carried out by green plants, green algae, and certain bacteria
Energy from sunlight is trapped and used for synthesis of glucose
Able to produce its own food
Organisms that cannot produce their own food
Green pigment
Contain coded information that controls the heredity of particular traits
Composed of three bases
Workhorses of the cell
Responsible for the expression of genetic traits
Complete set of DNA for an individual that contains all genes
Mutations occur due to
Errors in DNA replication or via a mutagen
Substance that induces mutations
DNA Polymerase
Enzyme that speeds up the process of DNA synthesis
Excision repair
Inspect the DNA for mutagens and attempt to repair it
Mismatch repair
Scans over the DNA to find any mismatches of bases
Germ Cells
Reproductive cells that give rise to sperm and ovum
Physical expressions of genetic traits
What can be seen or observed in an individual
Genetic makeup or code
"Letters-AA, Aa, aa"
Study of heredity and how traits are passed on from parent to offspring
Dominant Alleles
Capital Letters
Recessive Alleles
Lowercase Letters
Both parents give the offspring the same allele
Each parent gives the offspring a different allele for a particular trait
Punnett Square
Shows all the possible combinations of alleles
Incomplete Dominance
When the dominant and recessive genotypes interact to produce an intermediate phenotype
Mixture of two traits
The distance that light will travel within 1 year of time
Electromagnetic Waves
Waves of radiation that are characterized by electric and magnetic fields
Bands of Wavelengths from Short to Long
Gamma ray, Xray, Ultraviolet, Visible, Infrared, Microwave, and Radio waves
Color Bands from Long to Short
Red, Orange, Yellow, Green, Blue, Indigo, Violet
Ability to do work
Kinetic Energy
Energy of motion
Potential Energy
Stored energy
Conservation of Energy
Total constant energy is maintained by the conversion of energy between kinetic and potential
Law of Conservation of Energy
Energy is not lost but rather transferred back and forth between kinetic energy and potential energy
Anything that takes up space and has mass
Not the same as weight
Quantity of matter an object has
Substances that cannot be broken into simpler types of matter
Smallest part of an element that still retains all the original properties of the element
Positively charged subatomic particles found in the nucleus of an atom
Atomic Number
Number of protons in the nucleus of an atom of an element
Neutral subatomic particles found in the nucleus of an atom
Negatively charged subatomic particles found in various energy levels (orbital shells) around the nucleus
Subatomic Particles
Protons, Neutrons, Electrons
Chemical Reaction
Alters the chemical makeup of an atom
Positively or negatively charged atom
Atomic Mass
Number of protons and neutrons found within the nucleus of an atom
Same atoms that have different atomic mass
Rounded mass number
Control the rate of chemical reactions
Increase reaction rates by lowering activation energy
Row in the Periodic Table
The arrangement of electrons within orbits around the nucleus
Ionization Energy or Ionization Potential
Energy required to completely remove an electrom from a gaseous atom or ion
Measure of an atom's attraction on electrons in a chemical bond
Column in the Periodic Table
Displays elements that are similar in their chemical properties due to having a similar arrangement of outer shell electrons
Excellent conductors of electricity and also cool and heat faster than nonmetals
Act as catalysts for special chemical reactions within the human body
Protein molecules
Catalyze both forward and reverse reactions so equilibrium is maintained
Measure of hydrogen ion concentration within a solution
Measure the strength of acidic solutions and the strength of basic solutions
Metabolic Pathways
Chemical reactions with a cell
Lower Activation Energy
Greater reaction rate to occur
Compete with the substrate by blocking its active sites, reducing activity
pH less than 7
Red in litmus paper
pH more than 7
Blue in litmus paper
Q: Suppose the activit of hydrogen ions in a solution is 1 part per ten thousand. Find the pH value of the solution. Is this a basic or acidic solution?
A: pH=4; acid
Q: What does a difference of one unit on the pH scale below represent?
A: A concentration difference of 10
Ionic Bond
Electrical attraction between ions of opposite charges
Covalent Bond
Sharing of electrons between atoms
Saturated Hydrocarbons
also called Alkanes
Most basic structure of the hydrocarbons
Single bonds
Unsaturated Hydrocarbons
Have one or more double or triple bonds between carbon atoms
One double bond-Alkenes
Triple bonds-Alkynes
Elements that may accept or donate electrons readily and possess a mixture of metallic and nonmetallic properties
Positive ion
Metallic ion
Negative ion
Nonmetallic ion
Lewis Structures or Lewis dot diagrams
Provide visual representations of covalent bonding between atoms of a molecule
Atoms are shown and surrounded by dots that represent each of the valence shell electrons
Why do two hydrogen atoms need to be connected together in the natural state?
Hydrogen exists only in pairs because the atom is unstable on its own. A covalent bond is necessary to make the atom stable
On the left side of the reaction sign (→); Are substances consumed or altered in the chemical reaction
Located on the right of the reaction sign (→); Substances formed as the results of a chemical reaction
Balancing Chemical Equations
Make certain that there are equal numbers of each atom on the reactant side and the product side
ex. ___NI₃→___N₂+___I₂
*Since adding the 2 to N, it also multiplies the it's still not balanced
=2NI₃→N₂+3I₂ Balanced
Electron donation to produce a more positive ion
Electron acceptance to produce a more negative ion
Chemical reactions in living organisms that are necessary to maintain life
Acid + Base =
Salt and Water
Ex. of Acid-Base Reaction
pH neutralization
Ex. of Oxidation-Reduction Reaction
Combustion, Photosynthesis, Metabolism
Polar Molecule
Polar Molecule
A molecule that possesses both positive and negative atomic structure
Pure Water
pH standard-acid base neutrality
Low electrical conductivity
Ratio of mass per volume
Ice is less dense than liquid water; therefore, it floats
Boiling Point in Celsius
Specific Heat
The energy required to raise one unit of mass of a substance by 1deg C; Enables water to undergo minor temperature changes compared to the environment
High Heat of Vaporization
The amount of heat necessary to cause a phase transition between a liquid and a gas; Large a mount of heat is needed to vaporize liquid
Creation of larger molecules
Creation of smaller molecules
Latent Heat
Related to the energy needed to cause a phase transition at a fixed temperature
Flow of energy due to a difference in temperature
Liquid to a Gas
Phase Transition
Alteration of the physical state between a solid, liquid, and gas
Gas Diffusion and Molecular Mass Formula
R1/R2 = square root (M2/M1)

R1 = rate of effusion of gas 1
R2 = rate of effusion of gas 2
M2 = molecular weight of gas 2
M1 = molecular weight of gas 1
Percentage of Volume Formula for Solutions
%v/v = (volume of solute) / (volume of solution) * 100
Accuracy vs. Precision in science
A measurement system can be accurate but not precise, precise but not accurate, neither, or both.

For example, if an experiment contains a systematic error, then increasing the sample size generally increases precision but does not improve accuracy. The result would be a consistent yet inaccurate string of results from the flawed experiment. Eliminating the systematic error improves accuracy but does not change precision.
Energy Pyramid
producers > primary consumers > secondary consumers > decomposers (tertiary consumers)
Which ion would you expect to dominate in water solutions of bases?

A) MgCl2
B) 2HCl
C) H+
D) OH-
D) OH-

As a general rule of thumb, for acid solutions [H+] > [OH-], for basic solutions [H+] < [OH-], for the neutral solutions or for pure water [H+] = [OH-]
Why doesn't a raindrop accelerate as it approaches the ground?

A) Gravity pulls it down at a constant rate.
B) Air resistance balances the gravitational force.
C) It's mass decreases, decreasing its speed.
D) Objects in motion decelerate over distance.
B) Air resistance balances the gravitational force.

Gravity in fact causes acceleration, making choice A incorrect--unless air resistance counteracts that acceleration, which it may easily do for an object as small and lightweight as a raindrop. Raindrops may lose mass (choice C)_, that that would not decrease their acceleration. Choice D violates Newton's first law of motion.
Formula for Momentum
momentum = mass x velocity or
p = mv
Formula for constant of variation

k= m(slope) or the constant of variation

used in figuring out slopes/variations in graphs
The dorsal body cavity is ______ to the ventral body cavity.

A. medial
B. deep
C. posterior
D. anterior
C. posterior

The dorsal body cavity contains the spinal column, making it posterior or toward the back of the body, compared to the ventral body cavity, which contains the structures of the chest and abdomen.
Which is a major difference between eukaryotic and prokaryotic cells?

A) Eukaryotes have DNA, and prokaryotes have RNA.
B) Eukaryotes are animal cells, and prokaryotes are plant cells.
C) Eukaryotes have nuclei, and prokaryotes have no nuclei.
D) Eukaryotes house ribosomes, and prokaryotes have no ribosomes.
C) Eukaryotes have nuclei, and prokaryotes have no nuclei.
Stages of Meiosis
1. prophase
2. metaphase
3. anaphase
4. telephase

Stages of Mitosis