Astrobiology PHYS 13: Chpt 4
Which of the following is a piece of evidence suggesting that all life on Earth evolved from a common ancestor? A) All amino acids in living organisms are "left-handed." B) All life on Earth requires liquid water. C) All life on Earth is carbon based. D) All life on Earth is built from membrane-enclosed cells.
A) All amino acids in living organisms are "left-handed." Both left-handed and right-handed versions exist naturally, and we have no known reason to think that one is more suited to life than the other, so the fact that all life uses the left-handed versions suggests a common ancestry.
Why do we say that life on Earth is carbon-based? A) Carbon forms the backbone of the molecules responsible for cell structure and function. B) Bones of animals are made mostly of carbon. C) Carbon is the most abundant element in living organisms. D) Carbon is the most abundant element on Earth's surface.
A) Carbon forms the backbone of the molecules responsible for cell structure and function. Note that carbon is not the most abundant molecule by mass; but it is the most important in terms of structure.
While we may never be able to prove that our Moon really formed in a giant impact, which of the following would give scientists greater confidence that the model is correct? Select all that apply. A) Finding evidence that other giant impacts occurred in our solar system, with a total number of impacts consistent with what models of solar system formation lead us to expect. B) Observing evidence of recent giant impacts in other solar systems that are currently in the process of formation. C) Smashing together two glass marbles in a laboratory and then gluing the remnants together to make marbles that have the same size ratio as the Earth and Moon. D) Creating more sophisticated models of the giant impact that correctly predict many detailed characteristics of the Earth and Moon. E) Having the giant impact model endorsed by a dozen Nobel prize winners.
A) Finding evidence that other giant impacts occurred in our solar system, with a total number of impacts consistent with what models of solar system formation lead us to expect. B) Observing evidence of recent giant impacts in other solar systems that are currently in the process of formation. D) Creating more sophisticated models of the giant impact that correctly predict many detailed characteristics of the Earth and Moon. In fact, we already have greater confidence for all three reasons. Models of solar system formation suggest that at least a few other giant impacts should have occurred in our solar system, and we do indeed see other solar system bodies that appear to have been involved in giant impacts (including Uranus and Pluto). Telescopic observations have revealed some evidence for giant impacts in other young solar systems. And scientists are continually refining models of the giant impact thought to have formed our Moon, and these models yield testable predictions that, at least so far, have proven valid.
What happens to the energy that the ground absorbs in the form of visible sunlight? A) It is returned upward in the form of infrared light. B) It is returned upward in the form of visible light. C) It makes the ground continually get hotter and hotter.
A) It is returned upward in the form of infrared light. Remember that objects emit thermal radiation characteristic of their temperatures. Earth's surface has a temperature for which its thermal radiation peaks in the infrared. In other words, Earth absorbs energy from space in the form of visible light, and returns this energy to space in the form of infrared light.
What do we mean by the "heavy bombardment"? A) It was the period early in the solar system's history during which most impacts occurred. B) It was the period during which the large impacts that formed the lunar maria occurred. C) It was the giant impact thought to have formed the Moon. D) It was a short period of time, dating to about 4.1 to 3.9 billion years ago, when there appears to have been a lot of craters forming on the Moon.
A) It was the period early in the solar system's history during which most impacts occurred. As time passed, fewer planetesimals on potentially impacting orbits remained, which is why the impact rate dropped over time.
Which of the following is not a greenhouse gas? A) Oxygen B) Methane C) Carbon dioxide D) Water vapor
A) Oxygen Diatomic molecules of oxygen (and nitrogen) do not absorb infrared radiation and therefore are not greenhouse gases.
All of the following statements are true. Which one provides strong observational support for the claim that greenhouse gases make a planet warmer than it would be otherwise? View Available Hint(s) A) Venus has a higher average temperature than Mercury. B) Mercury is much hotter than the Moon. C) Earth has a higher average temperature than Mars. D) Earth is the only planet with an ozone layer in its atmosphere.
A) Venus has a higher average temperature than Mercury. The fact that Venus is hotter than Mercury despite being nearly twice as far from the Sun tells us that its thick carbon dioxide atmosphere must warm it significantly—just as we expect from the theory of the greenhouse effect.
The property of growth and development appears to be A) a necessary condition, but not a sufficient condition for life B) both a necessary condition and a sufficient condition for life neither a necessary condition nor a C) sufficient condition for life D) a sufficient condition, but not a necessary condition for life
A) a necessary condition, but not a sufficient condition for life
Without the protection of the Earth's magnetic field, most of the atmosphere would by now have A) been lost into space B) frozen onto the surface C) dissolved in the oceans D) been destroyed by chemical reactions
A) been lost into space
Metabolism is a term that describes the A) chemical processes that occur inside cells B) rate at which molecules travel across cell membranes C) rate of cell division of bacteria D) breaking down of complex organic molecules by bacteria
A) chemical processes that occur inside cells
The two strands making up the double helix of DNA are said to be A) complementary B) corresponding C) paired D) matching
A) complementary
Scientists can estimate the age of a planetary surface by counting __________. A) impact craters B) erosion features C) tectonic features D) volcanoes
A) impact craters The key to this method is the fact that (1) most impact craters formed during the heavy bombardment, but additional impacts have occurred since, and (2) all solid worlds should have had similar frequencies of impacts over time. Therefore, when we see many impact craters, a surface must be old, still bearing its ancient scars. When we see few impact craters, the ancient craters must have been erased by other geological processes that occurred more recently, which means the surface is younger.
Earth's temperature remains fairly steady, which means that Earth must return nearly the same amount of energy to space that it receives from the Sun. In what form(s) does Earth return most of this energy to space? Check all that apply. View Available Hint(s) A) infrared light emitted by the surface and atmosphere B) visible light emitted by the surface and atmosphere C) visible light reflected by clouds D) visible light reflected by the surface E) ultraviolet light reflected by the surface
A) infrared light emitted by the surface and atmosphere C) visible light reflected by clouds D) visible light reflected by the surface The total amount of energy returned to space in these three forms of radiation is nearly equal to the amount of energy that reaches Earth in the form of sunlight, which is why Earth's average temperature stays fairly steady. (Note: global warming is occurring, but the change is taking place over time scales of years, which means the incoming and outgoing energy at any moment are quite closely balanced.)
Chemists refer to molecules containing carbon atoms as A) organic B) inorganic C) carbonic D) carbonaceous
A) organic
During the past few million years, ice ages were MOST LIKELY caused by A) small changes in the Earth's axis tilt and orbit B) changes in the energy output of the Sun C) changes in the distance from the Earth to the Sun D) changes in the heat released from the Earth
A) small changes in the Earth's axis tilt and orbit
What is the main factor that drives Darwinian evolution? A) the competition for finite resources B) the size of an organism C) the ability of an organism to harness the energy of the Sun D) the need to have sex
A) the competition for finite resources
The process of converting a sequence of nucleotides in a section of DNA to a sequence of nucleotides in RNA, as a precursor to protein synthesis is called A) transcription B) deciphering C) translation D) encryption
A) transcription
DNA has four chemical bases, which we call A, T, C, and G. The key reason that DNA strands can replicate when separated is that ________. A) it takes only three bases in a row to code for one amino acid B) A always pairs up with T and C always pairs up with G C) each base can pair up with any other base D) extra bases are always floating around in cells
B) A always pairs up with T and C always pairs up with G This means that the two strands of a DNA molecule are always complementary, and each can serve as a template for forming a new strand of the other.
Which of the following mutations would you expect to have the greatest effect on a living cell? A) A mutation that changes a single base in a region of noncoding DNA B) A mutation that deletes one base in the middle of a gene C) A mutation that changes the third letter of one of the three-base "words" in a particular gene D) A mutation that duplicates an entire gene
B) A mutation that deletes one base in the middle of a gene This type of mutation will change the way the gene codes for amino acids and will almost certainly make the protein built by the gene nonfunctional.
When humans get hot, they sweat in order to reduce their body temperature. Which of the key properties of life is this an example of? A) order B) response to environment C) reproduction D) growth and development
B) response to environment
As discussed in the Extraordinary Claims box, when the giant impact idea was first proposed, it was generally thought to be so unlikely that it wasn't seriously considered until decades alter, after the Apollo missions to the Moon. What key piece of scientific understanding was missing that made it seem so unlikely when first proposed? A) An understanding of the difficulty of gravitationally capturing a body as large as our Moon. B) An understanding of the number and size of leftover planetesimals in the early solar system. C) A precise age for the solar system. D) An understanding of how heavily cratered the Moon's surface is.
B) An understanding of the number and size of leftover planetesimals in the early solar system. Models of solar system formation were not yet sophisticated enough to have made the idea of giant impacts seem plausible. The likelihood of a giant impact only began to seem reasonable after we understood that many large, leftover planetesimals would have been roaming the early solar system.
How do we determine where an organism belongs in the tree of life? A) By observing its physical characteristics B) By comparing its DNA to that of other organisms C) By classifying its metabolism according to its sources of nutrients and energy D) By the age of its oldest known fossils
B) By comparing its DNA to that of other organisms The tree of life, with the three domains bacteria, archaea, and eukarya, is based on genetic comparisons of DNA. The more closely DNA sequences match up, the more closely two species are related.
Which of the following best describes the relationship between fossil evidence for evolution and Darwin's theory of evolution. A) Fossil evidence shows that evolution really occurred, and Darwin's theory is a guess about how evolution might occur. B) Fossil evidence shows that evolution really occurred, while Darwin's theory provides a model for how evolution occurs. C) Darwin's theory can correctly predict every known feature of the fossil record.
B) Fossil evidence shows that evolution really occurred, while Darwin's theory provides a model for how evolution occurs. In other words, the fossil record establishes the fact of evolution, while the theory of evolution provides a model for how evolution occurs through natural selection.
Consider the following two facts: Any localized population of a speces has the potential to produce far more offspring than the local environment can support. Individuals in any population will vary in many hereditary traits. What did Darwin recognize as the obvious conclusion from these facts? A) All fossils must represent species that are extinct. B) Some individuals will be better able to survive and reproduce than others. C) Hereditary traits are passed on through DNA. D) Species must get larger and smarter with time.
B) Some individuals will be better able to survive and reproduce than others. These individuals will therefore be the ones that pass their hereditary traits on to future generations.
According to present understanding, which three features of Earth's geology are the most important in keeping Earth habitable on long time scales? A) Volcanism, plate tectonics, and erosion B) Volcanism, plate tectonics, and the magnetic field C) Impact cratering, volcanism, and erosion D) Impact cratering, volcanism, and plate tectonics
B) Volcanism, plate tectonics, and the magnetic field Volcanism was the original source of Earth's atmosphere, plate tectonics is crucial to climate stability, and the magnetic field shields the atmosphere against stripping by the solar wind.
Based solely on an understanding of the greenhouse effect (as displayed in the figure), which one of the following statements is true? View Available Hint(s) A) We do not yet understand the greenhouse effect well enough to make predictions about how it affects our planet. B) We should expect an increase in the greenhouse gas concentration to lead to global warming. C) Humans are causing global warming. D) Global warming poses a grave threat to our future.
B) We should expect an increase in the greenhouse gas concentration to lead to global warming. The evidence discussed in this tutorial makes it clear that greenhouse gases make a planet's surface warmer than it would otherwise be, so we should expect a rise in the greenhouse gas concentration to make Earth warmer. It is possible that there can be mitigating factors through feedbacks, but the basic link between greenhouse gas concentration and global warming is very strong. Provide Feedback
Bacteria reproduce by the process of cell division. This kind of reproduction is referred to as A) agamic B) asexual C) unsexual D) sexual
B) asexual
The composition of the early atmosphere of the Earth was dominated by A) oxygen (O2) B) carbon dioxide (CO2) C) hydrogen (H2) D) nitrogen (N2)
B) carbon dioxide (CO2)
Smaller worlds are more prone to atmospheric loss via impacts than large worlds because they A) are more likely to be hit B) have weaker gravities C) have no plate tectonics D) have less internal heat
B) have weaker gravities
What can be said about the presence of order in living organisms? A) it is both a necessary condition and a sufficient condition for life B) it is a necessary condition, but not a sufficient condition for life C) it is a sufficient condition, but not a necessary condition for life D) it is neither a necessary condition nor a sufficient condition for life
B) it is a necessary condition, but not a sufficient condition for life
How many different amino acids make up proteins found in virtually all life on Earth? A) 23 B) 4 C) 20 D) 5
C) 20
Consider the three items from Part A that are not relevant to the giant impact hypothesis. As you'll learn in later chapters, the lack of volcanoes is a result of the Moon's relatively small size. But what explains the other two items — the Moon's synchronous rotation and gradually increasing distance from Earth? A) The giant impact would have caused the Moon to rotate synchronously, and the outward fling from the impact would explain the increasing distance. B) Synchronous rotation is simply a coincidence, and this coincidence in turn causes the Moon to move farther away with time. C) Both are results of tidal interactions between the Moon and Earth. D) Both are results of the Moon's small size.
C) Both are results of tidal interactions between the Moon and Earth. As discussed in the section of your textbook on tides, the Moon's synchronous rotation arose as tidal friction slowed the Moon's rotation until its period matched its orbital period. The Moon's gradually increasing distance is a result of the fact that tidal friction is still gradually slowing Earth's rotation, and this leads to forces that push the Moon outward in its orbit so that the total angular momentum of the Earth-Moon system remains conserved.
Why is the "carbon dioxide cycle" important to our existence? A) It will save us from the otherwise destructive effects of global warming. B) It is the cycle in which carbon dioxide is exhaled by animals and used by plants. C) Over long periods of time, it acts as a thermostat to keep Earth's temperature in a relatively narrow range. D) It is the cycle responsible for ice ages, which have had profound effects on our evolution.
C) Over long periods of time, it acts as a thermostat to keep Earth's temperature in a relatively narrow range. C) Over long periods of time, it acts as a thermostat to keep Earth's temperature in a relatively narrow range.
What do we mean by metabolism? A) The processes that occur metaphysically in living cells B) A process that facilitates or accelerates a chemical reaction that would otherwise occur much more slowly C) The chemical reactions that occur in living cells to provide energy and nutrients D) The changes that occur in species over time
C) The chemical reactions that occur in living cells to provide energy and nutrients Note that metabolic processes all involve chemical reactions that occur in cells.
What is Earth's lithosphere? A) The part of Earth that is made of rock B) The layer of Earth that resides between the crust and mantle. Recall that the core/mantle/crust layering is defined by composition, whereas the lithosphere is defined by rock strength. C) The rock of the crust and upper mantle D) The molten portion of Earth's core
C) The rock of the crust and upper mantle This rock is relatively cool and rigid, and essentially "floats" upon the warmer and softer rock of the mantle below.
According to modern evidence and the theory of evolution, what is the relationship between humans and chimpanzees? A) Chimpanzees and humans are both descended from gorillas. B) We are descended from chimpanzees. C) We share a common primate ancestor with chimpanzees.
C) We share a common primate ancestor with chimpanzees.
Based on its distance from the Sun and the amount of sunlight absorbed by its surface, calculations predict the global average temperature of the Earth would be A) close to the freezing point of water B) above the boiling point of water C) below the freezing point of water D) exactly the same as it is measured to be today
C) below the freezing point of water
Most likely, before biological evolution there was A) physical evolution B) no evolution of any kind C) chemical evolution D) geological evolution
C) chemical evolution
The greenhouse effect raises Earth's surface temperature (from what it would be otherwise) because the infrared light radiated by Earth's surface __________. View Available Hint(s) A) travels directly out to space B) becomes permanently trapped by greenhouse gases C) is absorbed by greenhouse gases, slowing the escape of this energy to space
C) is absorbed by greenhouse gases, slowing the escape of this energy to space As shown in the interactive figure and discussed in your textbook, the infrared light ultimately escapes to space, but its absorption and re-emission along the way has the overall effect of increasing molecular motions that raise the air temperature from what it would be otherwise.
Why might we think that silicon would be an obvious alternative to carbon as a building block for biological molecules? A) it forms the basis of some life forms on Earth B) it forms complex molecules like carbon C) it has a similar electronic structure to carbon, forming a maximum of four bonds and, hence, should have a similar chemistry D) it has a similar abundance on Earth to carbon
C) it has a similar electronic structure to carbon, forming a maximum of four bonds and, hence, should have a similar chemistry
How is RNA different from DNA? A) it consists of a triple helix rather than a double helix B) its strands are much longer than DNA C) it is single stranded rather than consisting of a double helix D) its monomers do not contain nucleotide bases
C) it is single stranded rather than consisting of a double helix
Why can't the carbon dioxide cycle easily correct for the increasing amounts of carbon dioxide introduced into our atmosphere by industrialization? A) pollution has stopped the carbon dioxide cycle from operating B) the carbon dioxide cycle only influences carbon dioxide produced by natural sources C) it operates far too slowly to correct for any short-term changes D) it operates far too quickly to correct for any short-term changes
C) it operates far too slowly to correct for any short-term changes
Which is the MOST important property of the element carbon that makes it ideal as a fundamental building block of biological molecules? A) it is a very stable element B) it is a common element C) it readily forms chemical bonds with itself and other elements, allowing a wide variety of complex molecules to form D) it is the only element capable of bonding to itself
C) it readily forms chemical bonds with itself and other elements, allowing a wide variety of complex molecules to form
The walls of cells are referred to by biologists as A) linings B) coats C) membranes D) shells
C) membranes
A sterilizing impact is one during which A) all life on a planet is completely destroyed B) a planet is fragmented into pieces C) most life on the surface of a planet is destroyed but life in the oceans or beneath the surface might survive D) life on a planet is rendered incapable of reproduction
C) most life on the surface of a planet is destroyed but life in the oceans or beneath the surface might survive
Enzymes are catalysts which means that they A) slow down biochemical reactions which would normally occur too quickly B) prevent unwanted biochemical reaction occurring C) speed up biochemical reactions which would normally occur too slowly D) destroy harmful chemical species
C) speed up biochemical reactions which would normally occur too slowly
Scientists cannot agree on whether viruses are living or not because A) they are much smaller than other simple living organisms B) they can reproduce but do not require any utilization of energy to do so C) they can only reproduce within a host cell and not independently D) under certain conditions they can reproduce, but they do not contain any DNA
C) they can only reproduce within a host cell and not independently
All living cells use the molecule adenosine triphosphate (ATP) A) to catalyze biochemical reactions B) as a building block for nucleic acids C) to store and release energy for biochemical processes D) to carry oxygen into cells
C) to store and release energy for biochemical processes
DNA is copied via a process called A) reproduction B) imitation C) duplication D) replication
D) replication
The idea that species evolve through natural selection is an inevitable conclusion from which two facts? A) (1) Some individuals will be larger than others. (2) These individuals will overpower smaller individuals. B) (1) Fossils show that different species have inhabited Earth at different times. (2) Some species have gone extinct. C) (1) Some individuals are predators. (2) Those individuals will hunt and eat prey. D) (1) Populations are capable of growing more than the environment will allow. (2) Individuals within populations vary.
D) (1) Populations are capable of growing more than the environment will allow. (2) Individuals within populations vary. Therefore, those individuals that are best suited to reproductive success will be more likely to pass down their heredity than less-suited individuals. This is the essence of natural selection.
The verdict at the end of the Extraordinary Claims box says "Likely correct, though may never be possible to prove definitively." In the context of models, which of the following best explains this verdict? A) Models are very vague, and cannot be used to make mathematically precise predictions. B) Models are not reality, and we can never trust their results to reflect what might happen in the real world (or universe). C) No model could ever be good enough to reproduce the major characteristics of the Moon. D) A model that precisely reproduces major characteristics of the Moon would seem likely correct, but we can't go back in time to see that it actually happened that way.
D) A model that precisely reproduces major characteristics of the Moon would seem likely correct, but we can't go back in time to see that it actually happened that way. Today's models use computers to make precise predictions based on mathematical formulations of the known laws of nature. When these predictions match reality (such as the successfully reproducing the major characteristics of the Moon) we have great confidence that they are on the right track, but we can't completely rule out that some other scenario would also produce the same result.
An organism's heredity is encoded in ________. A) evolution B) amino acids C) ATP D) DNA
D) DNA DNA is the molecule of heredity for all known life on Earth.
The fact that Earth's interior has denser metals in the core and lower-density rock nearer to the surface tells us that ________. A) as Earth formed, it started with a B) metal core, then accreted rocky material around that metals condensed before rock in the solar nebula C) Earth's interior is molten D) Earth's interior was once hot enough to have melted
D) Earth's interior was once hot enough to have melted In other words, the early Earth underwent differentiation that allowed denser materials to sink toward the center.
In which eon of Earth's history did the heavy bombardment occur? A) Archean B) Proterozoic C) Phanerozoic D) Hadean
D) Hadean
On a cloudless day, what happens to most of the visible light headed toward Earth? A) It is reflected by Earth's atmosphere. B) It is absorbed and reemitted by gases in Earth's atmosphere. C) It is completely reflected by Earth's surface. D) It reaches Earth's surface, where some is reflected and some is absorbed.
D) It reaches Earth's surface, where some is reflected and some is absorbed. Most visible light passes through our atmosphere, and this light heats the surface as it is absorbed.
You study two regions of the Moon. Region 1 is densely cratered. Region 2 is mostly smooth, with just a few craters. What can you conclude? A) Region 2 is an older portion of the surface than Region 1. B) Region 2 suffered a much larger impact than Region 1 ever did. C) Region 1 was hit by a lot more impacts than Region 2. D) Region 1 is an older portion of the surface than Region 2.
D) Region 1 is an older portion of the surface than Region 2. The smoothness of Region 2 tells you that its early craters were covered by a lava flow, so it must be the younger region.
Which of the following seems most plausible as a simple definition of life? A) The ability to grow in an ordered pattern B) The ability to change in response to environmental stimuli C) The ability to use energy to fuel growth D) The ability to reproduce and evolve
D) The ability to reproduce and evolve As discussed in the text, evolution appears to hold the key to understanding all the other properties of life.
According to scientists, the naturally occurring greenhouse effect makes Earth about 31∘C warmer than it would be if there were no greenhouse gases in our atmosphere. How do scientists "know" what Earth's temperature would be without greenhouse gases? View Available Hint(s) A) They estimate it by averaging guesses made by many individual scientists. B) Ancient fossils allow them to infer Earth's temperature at a time before our atmosphere contained greenhouse gases. C) They assume that this temperature would be about the same as the temperature of Mars, which has much less of an atmosphere than Earth. D) They calculate this temperature from Earth's reflectivity and distance from the Sun.
D) They calculate this temperature from Earth's reflectivity and distance from the Sun. Aside from the greenhouse effect, the only factors that affect a planet's average temperature are its reflectivity and distance from the Sun. Since both distance and reflectivity have been measured, the expected temperature can be calculated easily and precisely. (Note that this assumes that the Sun's total emission of energy remains steady; measurements and theory both indicate that it varies very little over time scales less than a few million years.)
Greenhouse gases in the atmosphere, such as carbon dioxide and water vapor, make Earth warmer than it would be otherwise because these gases __________. A) reflect visible light coming from the Sun B) absorb visible light coming from the Sun C) form clouds that emit thermal radiation D) absorb infrared light emitted by the surface
D) absorb infrared light emitted by the surface Although the absorbed infrared light is quickly reemitted, it is reemitted in a random direction. As a result, greenhouse gases tend to slow the escape of infrared light from Earth to space, so that there is more heat (which means more energy) in the atmosphere than there would be if the infrared light escaped directly to space.
More than 96% of the mass of living cells are made of A) carbon and hydrogen B) carbon C) hydrogen and oxygen D) carbon, hydrogen, oxygen, and nitrogen
D) carbon, hydrogen, oxygen, and nitrogen
Differentiation is a process by which A) the Earth's surface separated into continents and oceans B) convection mixed up the materials in the interior of the Earth C) less dense materials like rock sank to the center of the Earth while denser materials like iron rose to the surface D) denser materials like iron sank to the center of the Earth while less dense materials like rock rose to the surface
D) denser materials like iron sank to the center of the Earth while less dense materials like rock rose to the surface
Given the Earth's larger size and strong gravity, the Earth's surface should have more impact craters than the Moon. However, it has very few. Why is this? A) the Moon acted like a shield, protecting the Earth from most impacts B) the Earth's surface was almost completely molten during the Hadean Eon so no impact craters were formed C) almost all impacts occurred in the oceans so no impact craters were formed D) geological processes like plate tectonics, volcanism, and erosion have erased them
D) geological processes like plate tectonics, volcanism, and erosion have erased them
The number of species of plants and animals that have been identified on Earth's surface is in the __________. A) trillions B) billions C) thousands D) millions E) hundred thousands
D) millions
The above idea that those individuals best-suited to survivial and reproduction will be the ones that tend to pass on their traits to future generations is called ___________. A) the theory of evolution B) the inescapable conclusion C) individual variation D) natural selection
D) natural selection
The leading hypothesis for Venus's lack of a global magnetic field is its ________. A) distance from the Sun B) lack of plate tectonics C) lack of a molten region in its core D) slow rotation
D) slow rotation The three general requirements for a global magnetic field are an interior region that is molten or fluid, convection in that fluid, and at least moderately rapid rotation. Venus rotates extremely slowly, so that probably explains its lack of a magnetic field.
Darwin's theory of evolution by natural selection therefore predicts that there must be some mechanism by which hereditary information is passed along from parents to offspring. What is the current status of this prediction? A) It was verified by careful studies of fossils. B) It is accepted on faith by the scientific community, even though there is no evidence that the prediction is correct. C) It has not yet been verified. D) It was verified by Darwin's own observations of finches in the Galapagos Islands. E) It was verified by the discovery of DNA and how it works.
E) It was verified by the discovery of DNA and how it works. In that sense, the discovery of DNA and the genetic code was a tremendous predictive success for the theory of evolution.
The energy that warms Earth's surface comes primarily in the form of __________. View Available Hint(s) A) heat from the Sun B) heat from Earth's interior C) ultraviolet light from the Sun D) infrared light from the Sun E) visible light from the Sun
E) visible light from the Sun In the figure, this fact is illustrated by the yellow squiggly line at the far left.
Each of the following statements is best associated with one of the four major geological processes. Drag each statement into the correct bin for its associated process. A) Mostly occured during heavy bombardment B) Affected all solid world similarly C) Created the smooth lunar maria D) Erased virtually all craters on Io E) Responsible for the existence of Earth's atmosphere and oceans F) Includes surface compression that builds mountains G) On Earth, involves motion of plates. H) Includes features sculpted by wind
Impact Cratering: A) Mostly occured during heavy bombardment B) Affected all solid world similarly Volcanism: C) Created the smooth lunar maria D) Erased virtually all craters on Io E) Responsible for the existence of Earth's atmosphere and oceans Tectonics: F) Includes surface compression that builds mountains G) On Earth, involves motion of plates Erosion: H) Includes features sculpted by wind
The statements below are all true. Some of them represent important reasons why the giant impact hypothesis for the Moon's formation is taken seriously, and some of them are not relevant to deciding between this and other hypotheses. Sort the statements into the correct bin according to whether or not they provide important support to the giant impact hypothesis. A) Models indicate early solar system had Mars-size leftover panetesimals B) Moon's composition is similar to Earth's mantle C) Moon has a low proportion of easily vaporized ingredients D) Moon lacks active volcanoes E) Moon's distance is gradually increasing F) Moon has synchronous rotation (keeps same face to Earth)
Supports giant impact hypothesis A) Models indicate early solar system had Mars-size leftover panetesimals B) Moon's composition is similar to Earth's mantle C) Moon has a low proportion of easily vaporized ingredients True but not relevant to giant impact hypothesis D) Moon lacks active volcanoes E) Moon's distance is gradually increasing F) Moon has synchronous rotation (keeps same face to Earth) Note the importance of the combination of modeling and observations. Models help us understand what conditions must have been like in the early solar system, showing that there must have been a great many leftover planetesimals, some large enough to cause giant impacts. Observations of the Moon's composition show that it is consistent with formation in a giant impact, which would have led to have a composition similar to Earth's mantle (because it formed from material blasted out of Earth's outer layers) and low in easily vaporized ingredients (because these ingredients would have remained gaseous and therefore would not have participated in the Moon's accretion).
