SA 8- 11

Early terrestrial atmosphere: In order for organic molecules to have formed on the early Earth, which of the following gases must not have been present in the atmosphere in significant quantities? A. oxygen (O2) B. nitrogen (N2) C. carbon dioxide (CO2) D. argon (Ar)

A

Evolving dogs: The fact that different dog breeds have been bred by humans from a common wolf ancestor in just a few thousand years provides evidence for the theory of evolution because: A. It shows that hereditary traits can change over time. B. It shows that nature will always select the individuals best adapted for survival. C. It shows that smaller animals will evolve into larger ones. D. It shows that dogs have gained intelligence over time.

A

Flyby vs. Orbiter: Which of the following is not an advantage of a flyby over an orbiter or lander? A. A flyby can get closer to a world we are studying. B. A flyby can visit more than one world. C. A flyby does not require fuel for slowing down. D. A flyby is generally cheaper to build and launch.

A

Headwaters: The lack of any obvious source for many outflow channels on Mars suggests that the water originated from A. underground B. the atmosphere in the form of rain C. ancient melting glaciers D. the atmosphere in the form of snow

A

Iridium: Why does iridium found in the K-Pg boundary layer suggest an impact? A. The iridium concentration in the layer reflects what is commonly found in meteorites but not in Earth rocks. B. Iridium does not exist naturally on Earth. C. Iridium is produced from rock melted in impacts. D. The amount of iridium in the layer is so low that we conclude that the impact must have blasted iridium from Earth into space.

A

Isotopic evidence of ancient water on Mars: Isotopic evidence for the presence of significant quantities of liquid water on Mars in the past comes from the observation of A. an elevated ratio of deuterium to hydrogen in the atmosphere B. an elevated ratio of helium to hydrogen in the atmosphere C. the presence of carbon-14 in the atmosphere D. an elevated ratio of carbon-12 to carbon-13 in the atmosphere

A

Last Martian seas: Significant amounts of liquid water last existed on the surface of Mars during the ------ geological era. A. early (Noachian, before 3.7 billion years ago) B. middle (Hesperian, 3.7 to 3 billion years ago) C. recent (Amazonian, since about 3 billion years ago)

A

Learning from the extremes: The major lesson we have learned from the study of extremophiles is: A. Life can survive in an astonishing variety of environments. B. Not all life can generate energy through photosynthesis. C. Different life forms on Earth use different genetic codes. D. All life on Earth uses DNA as its hereditary molecule.

A

Martian channels: Approximately how old are most of the erosion channels--thought to be dried-up riverbeds--that are visible from orbit on the surface of Mars? A. at least about 3 billion years B. at least about 4.5 billion years C. approximately 1 billion years D. less than 500 million years

A

Martian greenhouse: Despite the fact that the martian atmosphere is composed almost entirely of the greenhouse gas carbon dioxide, its surface has a much weaker greenhouse effect than Earth. Why? A. Mars's atmosphere contains far less total gas than Earth's atmosphere. B. Mars's surface does not radiate any infrared radiation. C. Mars's atmosphere contains other gases that neutralize the greenhouse effect of carbon dioxide. D. Mars is too far from the Sun for a greenhouse effect to be possible.

A

Martian meteorites: What observation leads scientists to conclude that a particular meteorite came from Mars? A. chemical analysis suggesting a Mars-like composition B. the presence of red-colored rock C. tracing the meteorite's trajectory back to Mars D. a measured density that matches the average density of Mars

A

Martian polar atmosphere: During winter at a particular pole on Mars, some of the carbon dioxide in the atmosphere A. freezes out onto the surface B. escapes into space C. condenses into liquid on the surface D. is destroyed by ultraviolet radiation from the Sun

A

Martian water vapor: What is thought to have happened to much of the water vapor that was once in Mars's atmosphere? A. The water molecules were broken apart by solar ultraviolet light, and the hydrogen then escaped to space. B. The water molecules reacted with sulfur from volcanic eruptions to form sulfuric acid. C. The water molecules escaped to space at a time when the atmospheric temperature was very high. D. The water molecules were split into their component atoms by solar x-rays.

A

Necessary vs. Sufficient: Consider the act of breathing for a human. In terms of the words ``necessary'' and ``sufficient,'' we would say that breathing is -------- to keep a human alive. A. necessary but not sufficient B. sufficient but not necessary C. both necessary and sufficient D. neither necessary nor sufficient

A

Origin of Martian meteorites: How could a rock from Mars end up traveling to Earth as a martian meteorite? A. It must have been blasted from Mars's surface into space by a large impact. B. It must have been part of the object that struck Earth in the giant impact that formed the Moon. C. It must have been blasted from Mars into space by a huge volcanic eruption. D. It must have been launched into space during a particularly strong martian dust storm.

A

Stromatolite surfaces: Microbes near the tops of the so-called ``living stromatolites'' that exist today produce energy through photosynthesis. Assuming the same was true of microbes that made ancient stromatolites, what can we conclude? A. Life had already evolved significantly by the time the ancient stromatolites formed. B. The first living organisms on Earth were capable of photosynthesis. C. Life must have originated on Earth's surface with sunlight as its energy source. D. Plants had already evolved by the time the ancient stromatolites formed.

A

The Sun by Jove: Jupiter is at 5 au from the Sun and Neptune is at 30 au (on average). This implies that sunlight at Jupiter is about how many times brighter than starlight at Neptune, on average? A. 36 times B. 12 times C. 6 times D. 1/6 times E. 1/12 times F. 1/36 times

A

Thermodynamics: Thermodynamics is the name given to a branch of science that deals with: A. energy and the rules by which it operates B. high temperature environments C. living organisms that can survive in high temperature environments D. the effects of high-speed motion

A

Venusian Fossils: According to the textbook, what is the likelihood that we could find evidence of ancient life on the surface of Venus? (And why?) A. Low: Venus's young surface is covered with evidence of intense geologic activity that would destroy fossil evidence. B. High: Venus is similar in size and distance from the Sun and may have supported life in the past C. Low: numerical models suggest that Venus's runaway greenhouse kicked in very early. D. High: recently, ozone and phosphene were both detected in the atmosphere of Venus.

A

Where are the Martians now?: If life exists on Mars today, it is most likely to be found A. beneath the surface B. on the surface C. floating in the atmosphere D. buried in the polar ice caps

A

Witnessing impacts: Have we ever directly observed an asteroid or comet hitting a planet? A. Yes, more than once, on Jupiter. B. Yes, on Mars. C. Yes, on Venus. D. No.

A

Life in the Clouds: Jovian planets like Jupiter have elevation bands in which liquid water can be stable. Why are these worlds nevertheless unlikely to be hospitable as habitats? (Mark all that apply.) A. because of violent convective updrafts and downdrafts that displace the air to different environmental conditions B. their tremendous distance from the sun (and hence weakness of solar energy source) C. expected absence of organic molecules from which to build organisms

A &B

Lava lakes experience violent foundering and overturn of their frozen surface layers. Speculate about why this does not happen in water lakes in winter? (Mark all that apply.) A. Because normal water lakes do not have an internal or underlying heat source to drive convection. B. Because water becomes less dense (rather than more dense) when it freezes. C. Because sunlight cannot easily penetrate a surface ice layer

A and B

Catastrophic Consequences: Which of the following were harmful effects of the K-Pg impact that may have contributed to the mass extinction? (Mark all that apply.) A. alteration of the crust leading to enhanced volcanism B. direct shock wave damage C. intense heating of the atmosphere D. slight displacement of the planet from its orbit E. violent blast winds F. vaporizing of carbonates (strong greenhouse over long term) G. lofting of dust (blocking sunlight: global winter)

A, B,, C, E , F, G

Why Water: According to the textbook, which of the following are reasons that water is strongly favored as a liquid medium for life? (Mark all that apply.) A. It is a polar molecule that readily dissolves other polar molecules and leaves nonpolar molecules alone. B. It is transparent to visible light C. It floats when it freezes (insulating layers beneath it) D. It is stable as a liquid over a wide range of temperatures E. It is highly reflective in crystalline form (as ice)

A, C, D

Ancient stromatolites: Radiometric dating indicates that the oldest known stromatolites formed approximately ----- years ago A. 4.6 billion B. 3.5 billion C. 3.95 billion D. 2.0 billion years ago

B

Distinguishing Martian eras: Surface regions are identified with different eras in martian geological history based primarily on -------- in the region. A. the number of dried-up riverbeds B. the number of impact craters C. the predominant colors of the rock D. the number of volcanoes

B

Early fuel: The first living organisms on Earth probably obtained their energy from -------. A. sunlight B. chemical reactions involving inorganic minerals C. absorbing naturally occurring molecules of ATP from the environment D. eating other organisms

B

Extreme Mars: In what way are extremophiles found on Earth relevant to the search for life on Mars? A. If we find life on Mars, it will almost certainly be an extremophile that migrated from Earth. B. Some extremophiles survive in conditions that seem quite Mars-like, suggesting the possibility that life could survive on Mars. C. Extremophiles prove beyond doubt that life could exist on Mars today. D. Some extremophiles survive in environments that are colder than daytime temperatures on Mars, implying that life is very likely to exist on Mars's surface.

B

Fate of Martian oxygen: After water molecules were broken apart in Mars's atmosphere by solar ultraviolet light, what is thought to have happened to their oxygen atoms? A. they escaped to space B. they reacted and literally rusted the surface rock, giving Mars its rust-colored tint C. they formed new water molecules upon encountering hydrogen atoms D. they reacted with surface rock to form carbonate minerals

B

Fossil fuels: The fossil fuels that we use today are primarily the remains of: A. cyanobacteria from more than 2 billion years ago B. forests that arose around 360 million years ago C. dinosaurs D. plants and animals that lived prior to the Cambrian explosion

B

Heredity: An organism's heredity is defined as: A. the way in which it makes use of energy B. the set of traits that it can pass on to its offspring C. its general characteristics such as size and cellular structure D. the set of molecules that it uses in reproduction

B

Martian misfortune: Consider the hypothesis that Mars's climate change can be traced largely to the loss of its global magnetic field. Under this hypothesis, which key factor would explain why Mars lost its magnetic field but Earth did not? A. rotation rate B. planetary size C. distance from the Sun D. thickness of the crust

B

Martian solar wind stripping: The most important factor that allowed the solar wind to strip substantial amounts of gas from Mars was probably the A. damaging effects of impacts B. loss of the planet's protective magnetic field as it cooled C. increasing strength of the solar wind D. formation of the polar caps

B

Martian surface temperature: Compared to the average surface temperature on the surface of the Earth, the average surface temperature on the surface of Mars is A. about the same B. much lower C. just slightly lower D. much higher

B

Martian water today: Where might liquid water still exist on Mars today? A. in dark streaks visible on crater walls B. underground C. at the bottoms of craters near the poles D. intermittently in warmer surface regions near the equator

B

Martian winters: Due to its elliptical orbit, Mars is farther from the Sun during winter in its Southern Hemisphere than during winter in its Northern Hemisphere. This means that winter in Mars's Southern Hemisphere is ------- than winter in its Northern Hemisphere A. shorter and colder B. longer and colder C. longer and milder D. shorter and milder

B

Miller-Urey: The Miller-Urey experiment was designed to: A. discover how life first arose on Earth B. explore the organic chemistry that could have occurred with Earth's early atmosphere C. test the hypothesis that life migrated to Earth D. determine whether life was more likely to have originated in the oceans or on land

B

Orbiter vs. Flyby: The major advantage of an orbiter over a flyby is: A. The orbiter can get closer to the world we are studying. B. The orbiter allows us to study the world for a longer time period. C. The orbiter can collect samples of the atmosphere. D. The orbiter is cheaper to build and launch.

B

Significance of pre-cells: How is it thought that the existence of naturally forming ``pre-cells'' would have been important to the origin of life? A. Pre-cells are always capable of self-reproduction. B. Pre-cells would have entrapped and thereby facilitated more chemical reactions than would occur in the open ocean. C. Pre-cells provided protection against solar ultraviolet radiation. D. Pre-cells are held together by RNA.

B

Soot: By itself, the presence of soot in the K-Pg boundary layer suggests the occurrence of: A. an impact B. widespread forest fires C. iridium D. a mass extinction

B

Status of evolution: In biology today, the theory of evolution is generally regarded as: A. one of several equally important theories in biology B. the unifying theme of all biology C. an interesting but unverified idea about how life changes with time D. important to theoretical biology, but not very useful to modern medicine

B

The Birth of Fire: Based on current evidence, about when had the oxygen level in Earth's atmosphere built up high enough to allow fires to burn? A. about 66 million years ago B. about 200 million years ago C. about 600 million years ago D. about 2 billion years ago

B

When life started: The oldest evidence of life on Earth suggests that life arose fairly quickly once conditions allowed it because it dates to ---------. A. within a few million years after Earth formed B. about the time at which the heavy bombardment ended C. the age of the oldest known impact crater on Earth D. about the time that oxygen first became present in Earth's atmosphere

B

Impactful Evidence: Which of the following are telltale evidence of an impact event? (Mark all that apply.) A. fractured rock B. tektites (molten spherules) C. meteoritic metals D. soot layer E. impact crater F. shocked mineral crystal grains (esp. quartz)

B C D E F

Inhospitable Worlds: Which of the following environments are the least likely to support life today (choose 3)? (Mark all that apply.) A. Ceres B. small planetesimals C. Venus D. Europa (moon of Jupiter) E. Mars F. Mercury

B C F

Building blocks: Why are we reasonably confident that the building blocks of life are abundant elsewhere in the universe? (Mark all that apply.) A. Because the number of possible atomic combinations that can be used to make organic molecules is very limited. B. The processes that have generated them in our neighborhood appear to be prevalent in the universe (based on telescope observations) C. We have found them in meteorites (which derive from planetesimals)

B and c

Airless and Lifeless: What are the primary reasons that life is unlikely on airless worlds? (Mark all that apply.) A. since there is no air, it is impossible to breathe B. water freezes or sublimates at the surface C. the surface is exposed to constant impact bombardment D. these worlds tend to be smaller and less geologically active (no mixing of reactants to produce chemical energy sources)

B,D

C-13/C-12: In terms of the search for fossil evidence of life, why is it useful to measure the ratio of carbon-13 to carbon-12? A. The discovery of an unexpected ratio would tell us that life must have migrated to Earth rather than originating here. B. The ratio tells us whether the fossilized organism obtained energy from chemical reactions or from sunlight. C. The ratio is slightly different in living organisms and their fossils than in inorganic materials. D. The ratio can tell us the age of the fossil.

C

Compelling microfossils: Some of the oldest claimed microfossils were long controversial because although they appeared to look like fossilized cells, some scientists argued the structures had arisen through geological processes. Which of the following discoveries led most scientists to conclude they really are fossilized cells? A. Under inspection with more powerful microscopes, scientists could see details of the cell structure, including the cell membrane and DNA region. B. Some of the cells were found to have been in the process of consuming other cells at the time they were fossilized. C. The microfossils have a lower fraction of carbon-13 relative to carbon-12 than is found in nonbiological rocks. D. A vote was conducted among scientists who study early life, and the vote overwhelmingly favored the idea these microfossils are indeed individual cells.

C

Darwin's finches: The different species of finches that Darwin found on the Galapagos Islands show evidence of evolution through natural selection because: A. all the species compete for the same resources B. they are capable of interbreeding with each other C. they each have adaptations that suit their local environmental conditions D. some species are more successful than others

C

Darwin's legacy: Charles Darwin is generally credited with the theory of evolution because: A. He was the first person to recognize that species tend to change with time. B. He was the first person to propose a specific mechanism by which species might change with time. C. He proposed and provided strong evidence for the idea that species evolve through natural selection. D. He discovered that life passes on its heredity with the molecule we call DNA.

C

Evolution in action: Have humans ever observed evolution through natural selection actually occurring? A. No, evolution always proceeds far too slowly for us to actually observe it. B. Yes, but only among viruses and bacteria. C. Yes, not only among viruses and bacteria but even among larger species over periods as short as a few decades. D. No, the idea of evolution through natural selection is only a theory.

C

Going for a walk on Mars: To walk outside, an astronaut exploring Mars would need to wear A. warm clothing and an oxygen tank B. warm clothing only C. a full spacesuit D. warm clothing, an oxygen tank, and a large hat as a shield against solar radiation

C

Going viral: Viruses seem to represent something ``in between'' the living and nonliving because: A. They are generally much smaller than bacteria. B. They do not display order in their structures. C. They can only reproduce within a host cell, not independently. D. They do not contain DNA.

C

Hemispheric dichotomy: Compared to the northern hemisphere, the southern hemisphere of Mars has A. lower elevation and more impact craters B. lower elevation and fewer impact craters C. higher elevation and more impact craters D. higher elevation and fewer impact craters

C

In Hot Water: A liquid medium for life that is stable at higher temperatures is especially favorable because: A. high temperature environments are more commonplace than low temperature environments in solar systems generally B. thermal energy of water can provide an energy source for organisms C. chemical reactions can proceed at a faster pace at higher temperatures

C

Life and order: What do we mean when we say that living organisms display order? A. Different species arose one after another in time. B. Individuals within a species always have a particular birth order, with some born before others. C. The structures of living organisms display patterns rather than being arranged randomly. D. Cellular structures can be arranged in order of size.

C

Marine origins: Life probably did not originate on the land surface because: A. impacts would have destroyed any life that appeared B. water was not plentiful on land C. there was no ozone layer to shield the surface from solar ultraviolet radiation D. organic molecules were not present on the land

C

Martian atmospheric thinning: Which of the following probably did NOT contribute to the thinning of the Martian atmosphere during its early history? A. the photodissociation of water molecules by ultraviolet light in the atmosphere B. the stripping of the atmosphere by solar wind particles from the Sun C. the consumption of carbon dioxide by photosynthetic bacteria D. atmospheric gases being blasted into space by large impacts

C

Most Rare Ingredient: Which of the following conditions for life is probably the hardest to meet? A. sources of raw materials (organic molecules) B. sources of energy (chemical energy or starlight) C. a stable liquid medium (water or something else)

C

Oldest life: The oldest carbon isotope evidence suggests that life on Earth was already thriving on Earth more than ------ years ago. A. 4.6 billion B. 3.5 billion C. 3.95 billion D. 2.0 billion years ago

C

Origins of oxygen: Evidence suggests that most of the oxygen in our atmosphere was first released by A. the decomposition of dead organisms B. plants C. cyanobacteria D. oxidation reactions

C

Oxygen crisis: Which of the following best explains what we mean by the ``oxygen crisis'' in relation to the evolution of life on Earth? A. There was not enough oxygen in the early atmosphere for plants and animals to survive. B. The impacts of the heavy bombardment tended to destroy atmospheric oxygen. C. Most early life forms were not adapted to survive as the oxygen content of the atmosphere rose. D. Scientists are unable to explain how oxygen became an important component of Earth's atmosphere.

C

RNA world discovery: Which of the following discoveries made it seem plausible that early life on Earth used RNA as its genetic material? A. RNA has only a single strand. B. RNA uses 4 bases in its molecular structure. C. RNA can in some cases catalyze chemical reactions. D. RNA is more easily produced in the oceans than DNA.

C

Sample return: To date, what worlds have had successful robotic spacecraft visits that collected samples and returned them to Earth? A. all of the planets B. only Mars C. the Moon, a couple of asteroids, and a comet D. the Moon and Mars

C

Second Law of Thermodynamics: The second law of thermodynamics states that, when a system is left alone: A. the total energy of the system will not change B. the total amount of matter plus energy in the system will not change C. the system tends to become increasingly disordered with time D. the system tends to become more and more ordered with time

C

Stomatolites: The rocks called stromatolites are thought be: A. fossils of the first living organisms on Earth B. meteorites from Mars C. fossils of colonies of ancient microbes D. the oldest rocks found on Earth

C

Tharsis: The continent-sized Tharsis Bulge region of Mars was most likely formed A. from sediment that piled up due to past water erosion B. by plate tectonics C. by a plume of molten mantle material rising to the surface and forming a bulge D. from compressions in the Martian crust as the planet cooled and contracted

C

Icy Conditions: Which of the following worlds are known to have surface ice deposits? (Mark all that apply.) A. Venus B. Jupiter C. Mercury D. Moon E. Mars

C, D, E

Ancient Martian atmosphere: The ancient water erosion features on the surface of Mars suggest that the planet must have had a much A. warmer and thinner atmosphere in the past B. cooler and thicker atmosphere in the past C. cooler and thinner atmosphere in the past D. warmer and thicker atmosphere in the past

D

Avantages of DNA: Assuming life began with an ``RNA world,'' what advantage did it gain by later evolving to use DNA as its hereditary molecule? A. The bases that make up DNA are much more common in nature. B. Individual strands of DNA are more stable than strands of RNA. C. Less energy is required for DNA replication than for RNA replication. D. DNA is less prone to errors during replication than RNA.

D

Chicxulub: What is the key piece of evidence linking the Chicxulub crater in Mexico to the extinction of the dinosaurs? A. The crater is large enough to have been formed by the impact of a 10-kilometer wide asteroid. B. The crater is surrounded by shocked quartz, indicating an impact. C. The crater contains iridium. D. Radiometric dating shows that the crater formed at essentially the same time that dinosaurs went extinct.

D

Exoplanetary meteorite: Under the best of circumstances, it seems that a meteorite would require ----- to travel from an exoplanet to Earth. A. a few months B. a few years C. a few centuries D. millions of years

D

Extreme necessity: Although various extremophiles can survive in a wide range of conditions, one thing that they all need in order to survive and reproduce is: A. sunlight B. oxygen C. changing seasons D. liquid water

D

Fundamentals of life: Generally speaking, biologists consider the most fundamental, defining property of life to be: A. the ability to respond to immediate environmental changes B. the ability to reproduce C. having an orderly arrangement of structure D. the ability to undergo evolutionary adaptation over time

D

Jovian plunge: Which of the following best describes the fate of a spaceship plunging into Jupiter (assume very low speeds)? A. slowly cooked and exploded B. slowly frozen and exploded C. eventually collides with iron core at center D. slowly cooked and crushed E. slowly frozen and crushed

D

Life's provenance: Of the following choices, which one seems most likely as the site where life on Earth first originated? A. shallow ponds on land B. islands far from shore C. cool water in tide pools near the ocean shore D. hot water near deep-sea volcanic vents

D

Mars' past surface habitability: Based on current evidence, the greatest uncertainty in understanding whether and when Mars may have had a habitable surface concerns the question of A. whether liquid water has ever been present on its surface B. whether the surface ever had a large and deep ocean C. the amount of water that was present on the surface D. the length of time for which liquid water was present on the surface

D

Martian atmospheric pressure: Compared to the atmospheric pressure at sea level on Earth, the atmospheric pressure on Mars is A. about the same B. just slightly lower C. much higher D. much lower

D

Molecular changes: Today, we know that evolution proceeds on a molecular level through changes in an organism's -----------. A. cell structure B. metabolism C. ATP D. DNA

D

Northern Martian ocean: What evidence supports the hypothesis that a vast, deep ocean once occupied what are now the northern plains of Mars? A. many of the largest flood channels appear to have drained into the northern plains B. geographic features that look like ancient shorelines C. the rock along the proposed shoreline is sedimentary rather than volcanic D. all of the above are evidence

D

Planetary visits: Which of the seven other planets (besides Earth) in our solar system have been visited by robotic spacecraft? A. only Venus and Mars B. only Venus, Mars, and Jupiter C. all except Uranus D. all of them

D

Sources of organic molecules: Which of the following is not likely to have been a source of organic molecules on the early Earth? A. chemical reactions occurring due to the heat and pressure generated by large impacts B. chemical reactions near deep-sea volcanic vents C. molecules brought to Earth within meteorites D. chemical reactions between iron in rocks and oxygen in the atmosphere

D

The Cambrian One-off: Which of the following is a likely reason for why an explosion of animal diversity similar to that of the Cambrian Period hasn't happened again since that time? A. The rate of evolution has dramatically slowed. B. Such an explosion can occur only for simple organisms and not complex ones. C. There are no more ecological niches available to allow this to happen. D. The widespread presence of efficient predators makes it much more difficult for entirely new types of animals to gain a foothold.

D

Why the Cambrian exploded: Which of the following is not considered to be one of the four factors that may have contributed to the Cambrian explosion? A. the rise of oxygen in the atmosphere B. genetic complexity reaching a critical level C. climate change due to the end of the last snowball Earth episode D. the nearly sudden appearance of the first eukarya

D

ersistence of water on Mars: Liquid water cannot exist for very long on the surface of Mars today because A. it gets rapidly destroyed by solar ultraviolet light B. the surface temperature is too high C. it rapidly reacts with surface rocks to form peroxides D. the atmospheric pressure is too low

D

Too extreme: Which of the following is not an environment in which we have found living organisms on Earth? A. inside the cores of nuclear reactors B. in rocks deep underground C. in water near deep-sea vents that is well above the normal boiling temperature of water D. in molten lava flowing from volcanoes

D. in molten lava flowing from volcanoes