Fall 1999

Lecture Exam 2--KEY
[Note -- On this key, any explanations that I have added to the correct answers are in brackets.]

This exam consists of 50 multiple-choice questions. Each one has only one right answer.

Read each question and all possible answers carefully before answering! Mark your answers on the Scantron form provided, using only a #2 lead pencil. If you erase an answer, make sure you erase it completely, or the machine may mark it incorrect. Check carefully to ensure that your answers are on the correct rows on the Scantron form.

Turn in both the Scantron form and the test paper when you are finished. Make sure your name is on both. You may write on the test paper if you wish, but anything you write on the test paper will not be graded.

Good luck.

Imagine that you have a pet budgerigar, or "budgie", (a type of tropical bird often kept as a pet) with green feathers. Your neighbor happens to have a blue budgie of the opposite sex. When your neighbor goes on vacation, you offer to keep his blue budgie in your own home. The inevitable happens, and before you know it, you have a whole nest of bouncing baby budgies on your hands.

1. Suppose that all the baby budgies grew up to be a bluish-green color, somewhere in between the colors of their parents. The simplest explanation for this would be
incomplete dominance

2. As it happens, all the baby budgies grow up to be green. This suggests that
the green allele is dominant over the blue allele

3. Suppose you keep one of these green baby budgies, and when it's grown, you mate it with a blue budgie. How many of the resulting offspring should have blue feathers?
one-half

You raise all the green baby budgies to adulthood, and then something horrifying happens: One of them mates with his sister! However, since you're in Arkansas, you know how to deal with this situation. And so you dutifully raise all of the resulting chicks.

4. What would you call this generation of budgie chicks?
the F₂ generation

5. About how many chicks in this generation will grow up to have blue feathers?
25%

6. Much to your surprise, one of the chicks grows up to have pure white feathers. What's probably happened here?
mutation

7. A pet store owner tells you that white budgies are rare and valuable, while green and blue budgies are quite ordinary. You promptly set most of your green and blue budgies free, and breed your white budgie until it collapses from sheer exhaustion. Any offspring that are white, you also save for breeding. After some years, you have a large flock of white budgies, which you sell for top prices. What have you done?
artificial selection

8. A rival of yours tries to imitate your success. He tries taking some ordinary green budgies, dipping them in bleach until they turn white, and then breeding them, hoping that the white color will turn up in their offspring. What he is hoping will be true?
Lamarckian inheritance

9. Imagine that the green and blue budgies that you got rid of survive and breed freely in the wild, but are hunted and eaten by hawks, eagles, and owls. Green budgies blend in well with green foliage, but blue budgies stand out more, and so are much easier targets for predators. What will happen over several generations?
blue budgies become rare due to natural selection

10. Coconut trees produce only a few seeds each year. Each seed is protected by a thick seed coat and richly supplied with nutrients that will sustain a growing embryo for a long time. Therefore, coconut trees are
K-selected organisms [Yes, plants can be r-selected or K-selected too, and don't you forget it!]

11. Which scientist is credited with developing the modern principles of uniformitarianism?
Lyell

Marfan's syndrome is an inherited disorder in humans, caused by a single allele that follows Mendel's laws. People with Marfan's syndrome tend to be tall and slender, with long limbs, long fingers and toes, flat feet, and poor eyesight. (Abraham Lincoln may have had it.) Because of their height, some people with Marfan's syndrome have become champion basketball or volleyball players (such as U.S. Olympic volleyball player Flo Heyman, whose team won the silver medal in 1984). However, people with Marfan's syndrome also tend to develop heart and blood vessel abnormalities, and may die suddenly when major blood vessels burst. (Flo Heyman died at 31 from a burst aorta.)

Questions 12-17 refer to this pedigree of a family with a history of Marfan's syndrome. A black dot indicates a person who has or had Marfan's syndrome. A question mark indicates that it's not certain whether a person has the syndrome.

[Questions 12 and 14-17 were DELETED from the grading. The pedigree on the exam is ambiguous: it could have been interpreted in more than one way.]

13. Person E is
a female [Represented by a circle on the pedigree chart]

18. Your eyes and an insect's eyes both have the same function, but their structures are radically different. This makes them
analogous

19. About 240 million years ago, the Earth's continents were clumped together in a single supercontinent called
Pangaea

20. In the graph on the right, what does N stand for?
population size

21. What does the dashed line labeled K represent?
carrying capacity

22. What type of curve is shown on the graph?
sigmoid

23. Evolution
amounts to change over time

24. All of the nutrient cycles depend in some way on the sun - but which of these cycles is most directly driven by the sun's energy?
hydrologic (water) cycle

If you come with me one summer and drive out to the Nopah Mountains in southeastern California, in the Mojave Desert, and hike around in the right areas, you'll find the layers of rock that are represented in the following diagram. Search in these layers, and you'll find fossils of arthropods called trilobites. Typical trilobites from the Nopah Mountains are shown on the right of the diagram. Questions 25-31 refer to this diagram.

25. As far as you can tell from this diagram, which layer is the oldest?
Wood Canyon Formation

26. What factors should be watched for, because they could potentially make it difficult to tell which layer is oldest?
all of the above

27. The fact that you find different trilobites in different layers illustrates
the principle of succession

28. Trilobites are no longer alive on Earth, as far as we know. Who was the first to document thoroughly that many animal species have gone extinct?
Georges Cuvier

29. Geologists have determined that the Wood Canyon Formation is about 540 million years old. What primary method did they use to arrive at this absolute age?
radiometric dating

30. What "great moment in evolution" was taking place around the time the Wood Canyon Formation was formed?
radiation of animals with hard shells [540 million years ago, as you know from question 29]

31. Part of the Wood Canyon Formation includes rock surfaces with a polygonal pattern of cracks. The same pattern is seen today in mud that has dried out when exposed to air (shown at the right). If you concluded that the Wood Canyon Formation was also once mud that dried out when exposed to air, you would be using: the principle of uniformitarianism

32. The half-life of carbon-14 is 5760 years. How much carbon-14 would be present in a sample that is 11520 years old?
one-fourth the original amount

33. Which of these is not a major factor in driving the carbon cycle?
lightning

34. In 1917, British botanist A. G. Tansley grew two different species of small weedy plants: rock bedstraw (Galium saxatile) and forest bedstraw (Galium sylvestre). When he grew each one singly, each species grew well. When he grew both together, one species always overgrew the other. (Exactly which species overgrew the other depended on what type of soil he used). This experiment demonstrated
competitive exclusion

35. Which of the following statements is not part of the theory of natural selection?
Traits acquired during life can be passed on to future generations.

36. A woman with type A blood gives birth to an illegitimate baby with type O blood. On the Jerry Springer Show, she names, cusses out, and then beats the ?*#! out of three Hell's Angels, any of whom, she claims, could have been the father. The three bikers have blood types AB, A, and B respectively. Which one cannot possibly be the father?
the one with AB blood

37. Large amounts of nutrients entering a pond or lake causes a situation called eutrophication. Which of the following is not a plausible consequence of eutrophication?
death of all living things in the water

38. "Pastor Glen", a street evangelist I once knew, told me one day that evolution by natural selection couldn't explain kindness, cooperation, and altruism among living things. As usual, he was wrong. But why?
Organisms may have a better chance of passing their genes on if they cooperate.

39. My nutrition-conscious mother says that eating cow liver is a bad idea, because you end up taking in all the toxins, heavy metals, pesticides, etc. that the cow's been exposed to. What ecological principle is she worried about?
biological magnification

40. The open grasslands of North America, Argentina, central Asia, and west Africa all together would make up a single
biome

41. An example of two organs that are homologous would be
your hand and a bat's wing

42. In a species of fish called the swordtail (Xiphophorus helleri), males have pointed extensions of their tail fins (see picture at the right). Females don't have these, but they show a preference for mating with males with longer "swords" This results in the evolution of males with longer swords by sexual selection

43. In the wild, the American bald cypress tree, Taxodium distichum, grows best in very moist or even waterlogged soils (such as in swamps, or in the shallows of Lake Conway). It doesn't tolerate shade or harsh winters well, and so is not usually found north of the state of Delaware. These factors describe its

44. To raise enough beef to feed one person takes about 1.5 tons of corn and soybeans. The same amount of corn and soybeans, used as a direct food source, could support over 20 people for the same amount of time. Why is this the case?
Most of the available food energy is lost at each trophic level

45. Arkansas black bears eat berries, nuts, honey, fish, and insects, among other things. Ecologically, they are
both primary and secondary consumers

46. Hugo de Vries, studying genetics of evening primrose flowers, noticed that occasionally, new alleles for flower color would appear suddenly, seemingly out of nowhere. The word he coined to describe these changes was
mutation

47. Erosion of rocks is important in driving the
phosphorus cycle

48. Suppose you cross two pea plants that are each heterozygous for the same two traits. There should typically be four types of offspring, in the ratio
9:3:3:1

49. The oldest fossils known are radiometrically dated at about ________ old.
3.5 billion years

50. The current President of the United States, a former Arkansas governor, is
The Great Pumpkin Bill Clinton