Clemson Biology Merit Exam
Answers
April 12, 2002
1. a) Correct. Poison ivy is a plant.
2. b) Correct.
c) No. The genus is Toxicodendron and the species is Toxicodendron radicans.
3. c) Correct.
4. c) Correct. Plants 3 and 4 are different genera, and should have the most genetic differences between them.
The fewest differences should be between 1 and 2, which are in the same species.
5. a) Correct. The fact that being poisonous is so widespread in unrelated groups implies that it originated
many times. The opposite would be true if being poisonous was almost universal in one group but not in
any other groups. This would imply it originated once in that group's ancestor.
b) No. If this were true, why are there so many nonpoisonous plants? As a matter of fact, as far as we can
tell, being poisonous doesn't give poison ivy any advantage in the wild.
6. b) Correct. Plant cells have cell walls.
7. a) Correct.
8. a) No. DNA never goes through a ribosome.
c) Correct.
9. d) Correct. Even if the students can't remember the exact structures here, they ought to be able to rule
out the other answers.
10. c) Correct.
11. a) No. It might be swelling against its cell wall and you wouldn't know.
b) Correct. Either it's swelling against its cell wall or it's at perfect equilibrium.
12. a) Correct. The protoplast begins to shrink when the salt concentration exceeds about 1.25%.
This is hypertonic to 0.85%.
13. a) Correct.
14. c) Correct. Sugar has more bond energy than CO2 and water.
15. d) Correct. Both the action spectrum of photosynthesis and the absorption spectrum of leaf
pigments have peaks in blue and red light.
16. b) Correct. The plant is producing more oxygen than it consumes.
d) No. Respiration is occurring during the daylight hours, but photosynthesis exceeds it.
Respiration without photosynthesis is occurring at night, though.
17. a) Correct. Photosynthesis barely exceeds respiration, so the oxygen concentration hardly rises.
b) and c) No. Oxygen concentration should rise sharply in these situations.
d) No. If respiration and photosynthesis both go up by the same amount, there should be a normal
increase in oxygen.
18. d) Correct. Each of these could either lower photosynthesis or speed up respiration once a
lot of photosynthesis had gone on.
19. a) No. This would mean that CO2 was high whenever O2 was high.
b) Correct. This graph shows that when O2 is high, CO2 is low, and vice versa. This is the pattern you'd
expect from photosynthesis and respiration.
20. c) Correct. This is the step that liberates the oxygen.
21. b) Correct. It's negative geotropism because the stem growing away from the earth. It's caused by
accumulation of auxin on the bottom of the stem, which causes that side to elongate faster.
22. a) Correct. The old stem is mostly wood, and the new stem is mostly pith and cortex.
23. d) Correct. All of these are dicot characteristics.
24. c) Correct, although the two OH groups on the benzene ring should give you a little pause.
However, this is the only reasonable answer.
d) No, plenty of large molecules (e.g., proteins, DNA) are water-soluble.
25. b) Correct. 1 g of urushiol contains 1,000,000 micrograms, or 500,000 doses of 2 micrograms each.
26. a) Correct.
c) No, that's xylem.
27. a) No, that would be an antibody-mediated response.
b) Correct.
c) No. Histamine is released from mast cells.
d) No. Plasma cells produce immunoglobulins. Erythrocytes are red blood cells.
28. d) Correct. This brings the neuron closer to threshold.
29. a) Correct.
30. b) Correct. They come from the adrenal cortex.
31. b) Correct. Pepsin will attack proteins in the stomach.
32. c) Correct.
33. a) No. If they lacked cytotoxic T-cells entirely, they'd die within days.
b) No. Albumin in the blood has nothing to do with immunity.
c) Correct. If there is no helper T-cell clone with receptors for urushiol, there will be no response to it.
34. c) Correct. If the resistant allele is R, the males are RY and the females are Rr. All the females
will either be RR or Rr (resistant). Half the males will be RY (resistant) and half will be rY (sensitive).
35. b) and c) No. Why should you suspect four alleles or four subunits?
d) Correct. The gel shows that slow degraders have two kinds of enzyme, and it sounds reasonable that half the
amount of good enzyme would result in reduced effectiveness at breaking down urushiol. Also, the fact
that there are three phenotypic classes hints that incomplete dominance is involved.
36. a) Correct. There are two codons in the DNA segment, and the complementary RNA nucleotides are shown.
37. a) Correct. An inhaled particle will hit the trachea after passing the larynx.
38. c) Correct.
39. b) Correct. The dye is purple Gram stain, and it only clings to Gram-positive cells.
40. a) Correct.
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