Science Behind the News

Geology 115 - Final Exam, May 200X

Name: _________________________________

THERE WILL NOT BE THIS MANY ESSAY QUESTIONS IN 2009 and the subjects were in a different order the year this exam was actually given].

[A] Asteroids, meteors and comets – oh no! The wide open spaces of space are inhabited by a variety of flying objects that potentially have interaction with Earth in their future. What is the difference between an asteroid and a comet, where do they come from, and why do we Earth dwellers care about their potential for landing nearby? (If possible use specific examples in your answer.)

Comets are balls of ice, gas, and dust that orbit the sun. They are composed of two parts: (1) a head that contains a nucleus (ice and dust) and a coma (gas and dust) and (2) a tail that contains dust blown from the head and a straight plasma tail. In contrast, an asteroid is believed to be composed of solid rock. The size of a comet differs from that of an asteroid. The nucleus of a comet is on the order of 10ís of km in diameter, the coma may be 1x10^6 km wide, and a comet tail is on the order of 150 km long. On the other hand, an asteroid may be smaller, on the order of 100 km in diameter. Comets and asteroids are found in different parts of the solar system: comets are spread out in orbit around the sun, while asteroids inhabit a distinct belt that separates the rocky planets from the gas planets.

Comets and asteroids also have similarities. Both comets and asteroids are believed to have been formed when the earth was formed, at ~4.6 Ga. Comets and asteroids occasionally orbit close enough to earth that they crash into this planet. The Cretaceous-Tertiary mass extinction is blamed (in part) on climate change and fires resulting from the impact of a comet or asteroid.

[B] In the "Life in Extreme Environments" module many unusual types of life were discussed. In a few sentences describe the range of conditions (temperatures, pressures, light conditions, etc…) over which scientists now know that life can and does exist.

Organisms are able to live at a range of conditions humans cannot tolerate. For example, thermophiles (heat loving organisms) thrive at temperatures from 45 C - 80 C and may be able to survive up to temperatures of 113 C - 150 C. Conversely, psycrophiles (cold loving organisms) do best in temperatures from 15 C - 20 C and can live at temperatures as low as 0 C. Life can also exist is highly acidic environments. Acidophiles (acid loving organisms) require surroundings of pH of 5-0. Some organisms live at pressure conditions not experienced on earthís surface. For example, some creatures live at deep sea vents, where pressure is ~250 times that on the surface of the earth. These organisms also thrive without sunlight. In sum, life can exist at a wide range of pressure, temperature, pH, and light conditions.

[C] Why/how does the temperature of the equatorial Pacific Ocean affect the weather throughout North and South America (and quite probably most of the rest of the world)?

Weather patterns are inextricably linked to oceans, because atmospheric circulation is driven by ocean convention currents. When neither El Nino or El Nina events are operating, warm water is pushed to the western portion of the Pacific Ocean, while cold water upwells on the eastern portion. However, when an El Nino event occurs, there is no west v. east thermal division in the Pacific. As a result, convection patterns are changed and therefore atmospheric circulation changes. Rain preferentially occurs in atypical locations, while other locations that typically receive lots of rain get less than normal.

[D] Fossilization involves the entombment and preservation of some or all of an ancient living organism. What makes amber such a special fossilization environment?

Amber is a preservant that provides particularly useful information on ancient life because it captures the 3-D structure of organisms and may also preserve samples of ancient air and water. Amber also fossilizes a wide range of organisms because resin (sap that may get hardened into amber) serves a variety of purposes for a tree. For example, resin can attract some organisms while repelling others. Amber is also particularly interesting because it preserves both recent and ancient life. Scientists have been able to extract information from organisms contained in amber that ranges from 100 years old to 125 Ma.

[E] List 3 greenhouse gases while defending one of the following 2 statements:

[a] Global warming is occurring and is mainly due to man-made causes.

Three primary greenhouse gasses are water vapor, methane, and carbon dioxide. These gasses allow solar energy to enter the atmosphere but prevent it from leaving, thus acting like glass in a greenhouse. Increases in levels of carbon dioxide are primarily due to human actions such as deforestation and fossil fuel emissions. The warming trend we have experienced in the last century is closely correlated with increases in manufacturing, increased gasoline emissions, and cutting down vast tracts of rainforests for farmland. The United States leads the world in production of greenhouse gasses, yet we refuse to make significant contributions to solving the problem, such as abiding by the Kyoto protocol. In sum, man has had a disproportionate contribution to the problem of global warming in a much faster time frame than naturally occurring causes of global warming.

[b] Global warming is not occurring, man's contributions are trivial compared to the natural fluctuations of the Earth's atmosphere and hydrosphere.

Global temperature continually, naturally fluctuates from hothouse to icehouse climates and is partly based on the concentration of naturally-occurring greenhouse gasses, such as water vapor, methane, and carbon dioxide. Volcanoes are particularly prolific producers of greenhouse gasses. In fact, when Mt. Pinatubo erupted in 1992, global climate changed for several years. Additionally, climate has wildly fluctuated long before humans were capable of creating greenhouse gasses. For example, the Cretaceous period (ended ~ 65 Ma) was a time when climate was much warmer than today, but the world was much colder during several intervals in the Pleistocene epoch (1.8 Ma – 10 Ka). Any effect humans may have will surely be overprinted by long-term natural changes.

[F] Why is it important to understand 'The Science Behind the News'?

Answer the remaining questions by circling the correct answer(s). (2-3 pts each) Some of the following questions have more than 1 correct answer.

1. Dinosaurs roamed the Earth between:

a) 220 and 65 thousand years ago

b) 100 and 35 million years ago

c) 220 and 65 million years ago

d) 500 and 65 million years ago

e) 300 million years ago and the end of the last Ice Age.

2. Which of the following gases are emitted from volcanoes:

a) carbon dioxide

b) water

c) sulfur dioxide

d) fluorine

e) all of the above

3. Bones are remarkably strong combinations of organic compounds and mineral matter. Which of the following sentences are true.

a) Fossil bones are strong and easy to recover from a dino dig.

b) Soft tissues like skin are routinely recovered during fossil digs.

c) The process of fossilization is very selective and unpredictable.

d) Most fossil skeletons are recovered nearly intact.

e) Footprints and feather imprints are considered to be fossils.

4. MTBE is a added to gasoline to help it burn more cleanly and is currently an environmental problem. Circle each of following that are true:

a) It survives in groundwater for much longer than do simpler hydrocarbon contaminants introduced into the water from a leaking gas tank.

b) It is actually not a problem because it is immediately degraded by biological activity beneath the surface.

c) Biological remediation using bacteria looks like a promising solution to this problem,

5. What is the real importance of trying to count all the bacteria and other simple prokaryotes in the earth? Circle the true statements.

a) A census is a valuable exercise just so we know how many there are.

b) If we can't count the simple organisms, how can we count the more complex ones?

c) There are so many of them that they make up a significant portion of the carbon budget of the earth.

d) Bacteria make some of the oxygen and nearly all of the nitrogen used by other living things.

6. In the discussion of possible life on Mars, there is an underlying assumption of the age of the planet itself. How old do we believe Mars to be?

a) 5.5 billion years, like our moon

b) 4.5 million years, like the earth

c) 3.5 trillion years, like the sun

d) 4.5 billion years like the earth

e) 5.5 million years like the asteroids

7. Which of the following lines of evidence have been cited as suggesting that life once existed on Mars:

a) Polycyclic aromatic hydrocarbons (PAHs), were found in fissures in the Martian meteorite.

b) The meteorite contained carbonate nodules, which are similar to nodules formed by life on Earth.

c) Shapes resembling life were found near these other clues.

d) DNA fragments were found associated with these shapes.

8. Which of the following statements is thought to best summarize the history of Mars and abundant liquid water:

a) Mars has never had liquid water on its surface, it is too cold.

b) Mars had a warmer and wetter climate more than a billion years ago.

c) It once rained on Mars but there never has been liquid water on the surface.

d) Like Venus, the surface of Mars is too hot to allow liquid water to exist.

e) Like our moon, the only liquid water observed is underground.

9. Gas inclusions in amber have proven that:

a) Earth's atmosphere once contained 35% oxygen.

b) Earth's atmosphere once contained less than 10% oxygen.

c) The Martian atmosphere contains less CO₂ than does the Earth's atmosphere.

d) Methane freely oozes through the structure of amber, leaving no trace.

e) None of the above.

10. What are the uncertainties surrounding the claim of a researcher that his team has grown ancient bacteria from spores recovered from fossils in amber?

a) Contamination from modern bacteria during the test.

b) Lack of confirmation by other independent labs

c) Bacteria didn't exist when the amber formed.

d) All of the above

e) Just a) and b) are correct

11. What is the term for a type of relationship between two life forms that benefits both?

a) Slavery

b) Parasitic

c) Luminescent

d) Palimony

e) Symbiotic

12. In the Extreme Life module there were a bunch of terms for groups of organisms that ended in the suffix '..philic'. This means that the particular organism:

a) Hates/can't stand that attribute (i.e. hydrophilic means it hates water)

b) Loves/needs that attribute (i.e. thermophilic means it loves heat)

13. Most of the world's earthquakes occur:

a) In the Mediterranean-Asiatic belt

b) In the interior of plates

c) In the circum-Pacific belt

d) In continental crust

14. What is the most probable source of water on the moon?

a) Radiation from the sun

b) Original water left over from the moon's formation

c) Bombardment by comets

d) A collision with Earth

e) Nuclear fusion

15. Astronomers believe that comets are about how old?

a) 300 million years

b) 100 million years

c) 4.6 billion years

d) 4.6 hundred thousand

e) they are forming in our solar system today between Mars and Jupiter

16. During the first 700 million years of Earth history which of the following were true and help us understand why life did not evolve earlier?

a) The Earth did not have an atmosphere.

b) There was life it just isn't preserved in rocks.

c) The Earth was too cold to support life.

d) The Earth was constantly being pummeled by asteroids and other space junk.

17. What is thought to be a major cause of asteroids wandering out of their home belt and potentially becoming a threat to Earth?

a) Impacts between cosmic rays and asteroids

b) Graviatational interactions between asteroids and planets.

c) Impacts of comets into the asteroid belt.

d) Gravitational interactions among the asteroids.

e) Chaos theory.

18. Which of these is(are) thought to be important (a) factor(s) in the decline of the monarchs?

a) Habitat destruction in the U.S. has left little room for the butterfly to live in the summer.

b) The decline is a natural fluctuation in the monarch's population.

c) Burning and destruction of forests in Mexico, the winter habitat for monarchs.

d) Herbicides are destroying weeds needed by monarchs (and other butterflies).

e) The heavy oxygen isotopes in their food makes them too heavy to fly.

T F Bioscientists have agreed on how to classify the living organisms of the Earth.

T F Dinosaurs were all reptiles.

T F Amber can not be formed in the tropics, you need to have pine trees.

T F Individual monarch butterflies have been tracked from Mexico to Kansas and back to Mexico.

T F The atmospheric circulation over the Pacific Ocean directly effects the fishing industry in South America.