Unformatted text preview: mation. The only possible answer, therefore, is B. For choices
C and D, no information is provided in the graphs.
39. A. Some knowledge about factors that affect enzyme activity is needed here. Within an
enzyme’s normal range of activity, a clear indication that all enzyme molecules are saturated
is a leveling off of the rate of reaction curve (an increase in enzyme concentration would help
increase activity again).
40. B. When enzymes are at work, they help bring their substrate(s) to the “transition state.” At
which time bonds can break and the reaction can proceed. To be able to do this, the enzyme
must be in an environment compatible with its range of activity. A pH below 5.5 is not
within the activity range of Enzyme B. Therefore, it would be unable to bring its substrate(s)
to the transition state.
41. C. A reaction that has negative heat change and increases in entropy is spontaneous. In
general, energy transformations proceed spontaneously to convert matter from a more
ordered, less stable form to a less ordered, more stable form. Answers A and B are the same,
with the reaction requiring energy to proceed and therefore not spontaneous.
42. B. An enzyme is a protein produced by an organism that lowers the activation energy of
reactions and increasing the reaction rate.
43. C. Negative feedback involves the product of the reaction inhibiting the enzyme from
creating more product. It does not destroy the enzyme (as in answer D).
44. A. The membrane that the liposome-DNA complex has to cross to gain access to the cell is
the cell’s external plasma membrane. This membrane consists of lipids and membrane bound
proteins, so option B is correct. All the membranes of the cell incorporate proteins, so option
D is incorrect. The cell membrane would be a very unlikely place to find DNA, so options B
and C are also incorrect.
45. D. Although rare in girls, DMD does occur in girls, precluding its location on the Y
chromosome (answers C and A – fathers pass only their Y chromosome onto sons). Mothers
pass X chromosomes randomly to their sons and daughters, so they could not control w...
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