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designed to isolate such a mutant. It is also possible (slightly) that two mutants arose in the
same cell with the same dose of radiation in Experiment 2.
31. D. The original suspension of bacteria contained normal cells that can grow on a minimal
medium. Regardless of how many cells mutated, there would be innumerable cells still able
to grow on this medium (cells that gave rise to Colony a and Colony B should also be able to
grow on a ampicillin-free medium!).
32. D. Basic knowledge of how bacteria can transfer genetic material is required. Only
transference is not a genetic transfer mechanism in bacteria.
33. C. Answer C is a false statement as antibiotics do not increase the mutation rate of bacteria.
Resistance is a phenomenon of selection, with resistant bacteria surviving the antibiotic
34. C. A basic knowledge of digestive processes is required (i.e., the stomach is a highly acidic
environment, whereas the small intestine is slightly alkaline). The lower part of the graph
shows that Enzyme A works best at a pH close to 2, while Enzyme B works best at a pH
closer to 8.
35. A. Because the two enzymes have two different, non-overlapping pH ranges, they could not
be at work in the same place at the same time. In addition, the graph does not refer to the
temperature ranges of A and B (only X and Y). Although Enzyme A generally works more
slowly than Enzyme B, neither enzyme works at all in pH 4.5.
36. B. The key to this question is the temperature range at which the two enzymes work. Only
Enzyme X has a temperature range encompassing human body temperature (37ºC). An
enzyme whose peak activity is close to 75ºC-80ºC (Enzyme Y) is unlikely to be found in the
human body. Page 4 of 12 37. D. Both enzymes overlap between 40ºC and 50ºC. Choices A and B are too broad, and each
includes a range of temperatures beyond which one of the enzymes cannot work.
38. B. When an enzyme is not active in a particular environment, it may be because that
environment affects its confor...
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- Spring '11