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Exam 2 ASTR
Terms in this set (58)
In which type of rock are fossils most often found?
Which types of radioactive decay cause the parent nucleus to become a different element or isotope (and thus are useful for radioactive dating)?
Both alpha and beta decay
redirects particles from the solar wind to keep them away from Earth, preventing its atmosphere from being stripped away
generates gas and liquid, creating Earth's atmosphere and oceans
by regulating the formation of oceans, continents and ocean currents, may contribute to long-term climate stability
Which eon of the geologic time scale is the only time period in Earth's history that doesn't yield any fossils (although life may have already existed)?
Hadean (4.6 to 4.0 bya)
which of the following is NOT true about the Earth's magnetic field?
the magnetic field deflects the charged particles from the solar wind like a force field that they bounce off of back into space
The Earth's atmosphere is transparent to which regions of the electromagnetic spectrum?
Visible and radio
_______ passes through the atmosphere without being absorbed, and causes the Earth's surface to become hotter
This heat is re-emitted from the surface in the form of ______, which gets continually absorbed and re-emitted by greenhouse gases in the lower atmosphere.
Ultimately, this leads to the _____ of the lower atmosphere
which is not one of the properties of life on Earth, as described in the lecture and the textbook?
relying on oxygen for respiration and carbon for building body structures
Darwin's "inescapable conclusion" that lead to the theory of evolution is
population pressure and individual variation leads to unequal reproductive success
in the context of the metabolic classifications of living organisms, the term _____ refers to an organism that only uses carbon dioxide to obtain the carbon necessary to build cellular structures
On the other hand, ______ refers to one that uses pre-existing organic compounds, for example, the structures of plants and animals, for raw material
Which of the following is not a true statement about mutations in an organism's DNA?
they are always lethal in the long run
What do scientists call organisms that live in places that are too cold/hot, too acidic/alkaline, too salty, or too irradiated for "normal" life to survive?
Which of the following (there may be more than one) are true of the domain Eukarya?
-includes all plants and animals
-their cells have a nucleus
How is geology crucial to our existence?
Earth's geology has made our planet habitable, ultimately allowing not only the existence of life but also the long-term evolution of life into complex forms that include us.
the three basic rock types, how are they formed, and in which do fossils arise?
Igneous rock: made from molten rock that cools and solidifies
Metamorphic rock: rock that has been structurally or chemically transformed by high pressure or heat that was not quite high enough to melt it
Sedimentary rock: made by the gradual compression of sediments, such as sand and silt at the bottoms of seas and swamps. Fossils are most commonly found in sedimentary rocks
Rock analysis; how to determine relative ages in layers of rocks
Mineralogical analysis generally means identifying the minerals present in a rock.
Chemical analysis: generally means determining the elemental or molecular composition of a rock or mineral. For example, chemical analysis will tell you the percentage of a rock that consists of iron, silicon, carbon, or other elements
Isotopic analysis: generally means determining the ratio of different isotopes. For example, oxygen has three stable isotopes: oxygen 16 is by far the most common, but it is always mixed with small amounts of oxygen 17 and oxygen 18; isotopic analysis can tell us the relative amounts of a the three oxygen isotopes in a rock
structure of the atom and its key components
Protons and neutrons are inside the atom's nucleus. Electrons surround the atom like a cloud. Isotopes of an element have the same amount of protons but a different amount of neutrons
where a large atomic nucleus ejects a helium nucleus. the remaining daughter nucleus has a lower atomic mass than its parent nucleus. Daughters have two less protons so they are a different element with a lower atomic mass
Determine absolute ages; radiometric dating, concept of half-life
Radiometric dating: most reliable method for measuring the age of a fossil, rock, or other solid objects. relies on careful measurement of an object's proportions of various atoms and isotopes
Half-life:: the time it would take for half of the atoms in a sample of the substance to decay
Out-gassing and development of earth's atmosphere
out gassing: when molten rock erupts onto the surface as lava, the release of pressure violently expels the trapped gas. Probably released most of the water vapor that condensed to form our oceans as well as most of the gas that formed our atmosphere.
Recent studies of come composition suggest that outgassing was more important to the formation of the atmosphere and oceans. volcanism is the major source of outgassing
geological activity, differentiation, plate tectonics
Differentiation: where materials separate according to their density. Earth's interior layering tells us that it underwent this process
importance of earth's magnetic fields
Earth's magnetosphere acts like a protective bubble, shielding our planet from the charged particles of the solar wind
transparency of the Earth's atmosphere and green-house gasses
Greenhouse gases such as carbon dioxide, methane, and water vapor absorb infrared light emitted from the planet's surface. the absorbed photons are quickly reemitted, but in random directions. the result acts much like a blanket, warming the planet's surface. without the warming due to the greenhouse effect, earth would be frozen
climate regulation, greenhouse effect
Earth's long-term climate is remarkably stable because of feedback processes that tend to counter any warming or cooling that occurs. The most important feedback process is the carbon dioxide cycle, which naturally regulates the strength of Earth's greenhouse effect. Earth's temperature has remained in a range allowing liquid water at least since the end of the heavy bombardment, but there have been periods of unusual warmth or cold. Recent ice ages are tied to small changes in Earth's rotation and orbit Geological evidence also shows more extreme variations in the past, including the snowball Earth episodes that ended more than 500 million years ago
What if we push Earth into the orbit of Venus? What would happen to Earth?
The water on Earth would evaporate immediately. Earth would no longer be in the habitable zone
Know the six defining properties of life
-growth and development
-response to the environment
explain Darwin's "mechanism of evolution". Fact one, fact two, and his inescapable conclusion
Darwin made a case for evolution in two fundamental ways. First, he described his observations of living organisms and showed how they supported the idea the evolutionary change really does occur. Second, he put forth a new model of how evolution occurs, backing up his model with a wealth of evidence. Darwin's theory of evolution explains how evolution happens.
Fact One discusses overproduction and competition for survival. Any localized population of a species has the potential to produce far more offspring than the local environment can support with resources such as food and shelter. This overproduction leads to a competition for survival among the individuals of the population
Fact Two discusses individual variation. Individuals in a population of any species vary in many heritable traits. No two individuals are exactly alike, and some individuals possess traits that make them better able to compete for food and other vital resources
The inescapable conclusion: unequal reproductive success. In the struggle for survival, those individuals whose traits best enable them to survive and reproduce will, on average, leave the largest number of offspring that in turn survive to reproduce. Therefore, in any local environment, heritable traits that enhance survival and successful reproduction will become progressively more common in succeeding generations
the basic unit of life-the cell. What are typical structures and major components of cells?
Why are living cells carbon-based? Why not oxygen-based? Why not silicon-based?
Carbon can have up to four bonds whereas oxygen can only have up to two bonds and mostly bonded to water molecules. Silicon's bonds are far weaker than carbon's, silicon does not normally form double bonds unlike carbon, and silicon doesn't have the same mobility that carbon does.
what are the four molecular components of cells and what are their functions?
Carbohydrates: source of food energy; make important cellular structures
Lipids: cans store energy for cells i.e. fats; lipids form barriers that make it possible for cells to exist
Proteins: serve as structural elements; enzymes that are crucial to biochemical reactions; catalysts; amino acids
Nucleic acids: DNA, RNA are responsible for allowing cells to function according to precise, heritable instructions
Be familiar with organic molecules and hydrocarbons. What is a chemical bond?
Chirality, or handedness. Which mirror image is all of life on Earth?
all life on earth has left handedness or left chirality
Two basic cell types: Prokaryotes and Eukaryotes; compare their properties
both have plasma membrane, both undergo cell division, both have cytoplasm, both have ribosomes and chromosomes.
Eukaryotic cells have membrane bound organelles and a nucleus
Tree of life (major groupings) of life: Bacteria, Archea, and Eukarya. Which are we?
Humans are a part of the Eukarya domain
The ATP-ADP metabolic cycle; phosphate groups
energy from food is used to bond phosphate groups to ADP molecules to form ATP. Energy is released into cell when ATP splits into ADP and a phosphate
cell metabolism; the four metabolic classifications and examples of each
How/why can a mutation like sickle cell disease provide an ecological advantage for individuals
sickle cell suppresses malaria. those with the mutation live longer and can pass it down to their offspring. the mutation becomes the dominant expression.
Understand and be familiar with extremophiles
can withstand extreme environments. Acid/alkaline, hot/cold, etc
The three main aspects geology and why are they important
Volcanism: volcanoes are important to our existence one a much deeper level. Volcanic activity releases gases trapped in Earth's interior, and these gases were the original source of Earth's atmosphere and oceans. Volcanism releases heat and creates chemical environments that, we suspect, helped lead to the origin of life on our planet.
Plate tectonics: Earth's surface has been shaped largely by the movement and recycling of rock between the surface and the interior. This process is best known for gradually rearranging the continents, but its most profound relevance to life involves Earth's climate-according to modern understanding, plate tectonics is largely responsible for the long-term climate sustainability that has allowed life to evolve and thrive for some four billion years
Earth's magnetic field: compass needles point north because our planet has a global magnetic field generated deep in its interior. You may know that the magnetic field has at least a few biological effects-for example, some birds use magnetic field to help guide their migrations-but its deeper significance is to our atmosphere. The magnetic field shields Earth's atmosphere from the energetic particles of the solar wind and without this shielding, it's likely that a significant portion of our planet's atmosphere would by now have been stripped away into space
when a nucleus spontaneously emits or absorbs an electron, causing one of its neutrons to turn into a proton, or a proton to turn into a neutron. the parent and daughter nuclei will both have the same atomic mass number, but they will represent different elements because they have a different number of protons (daughter gains a proton)
after alpha or beta decay, surplus energy is sometimes emitted. has a high frequency with a shorter wavelength. the atom is not changed (daughter element has the same number of protons so it is the same element with the same atomic number)
occurred during the Hadean eon (3.9-4.5 billion years ago)
Evidence of first life forms
occurred at the end of the Hadean eon and the beginning of the Archean eon (3.85 billion years ago)
rise of oxygen
occurred at the end of the Archean eon and the beginning of the Proterozoic eon (2.5 billion years ago)
occurred during the Cambrian period in the Paleozoic era (510-530 million years ago)
plants colonize land
occurred during the Ordovician period during the Paleozoic era (475 million years ago)
animals colonize land
occurred during the Silurian period during the Paleozoic era (appr. 415 million years ago)
mammals and dinosaurs appear
occurred during the Triassic period during the Mesozoic era (210-230 million years ago)
occurred on the edge of the Cretaceous and Tertiary periods during the end of the Mesozoic era and the beginning of the Cenozoic era (65 million years ago)
appear in the Tertiary period of the Cenozoic era
the four DNA bases
storing of information; set of "operating instructions" for the cell and a way of passing these instructions down through the generations
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