97' SBIOA Exam

Note:  I have used the terms NADH and NADH₂ and NADH/H⁺ interchangeably (i.e., they are all meant to be equal in meaning. So don’t look for tricks there.  Also, if I haven’t subscripted or superscripted stuff, don’t get hung up on that either.

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41.             Which of the following statements best describes the effect of genetic drift on the gene frequencies of a population?

a)                  Genes enter a population through immigration, thus changing gene frequencies.

b)                 Genes leave a population through emigration, thus changing gene frequencies.

c)                  Chance alone can cause significant changes in gene frequencies of small populations.

d)                 Mutations over time cause gene frequencies to change.

e)                  Selection against one allele causes gene frequencies to change.

42.              If the fossil record has few or no intermediate forms, if there are long periods in which the fossils underwent no morphological change, and if new forms arose very quickly, then evolution of these new forms would be best described as:

a)                  punctuated equilibrium.

b)                 adaptive radiation.

c)                  gradualism.

d)                 convergent evolution.

e)                  due to stabilizing selection.

43.             Coupled biochemical reactions are important in determining thermodynamic order within cells. Consider the following two reactions that occur simultaneously in cells:

1,3-bisphosphogylcerate ± 3-phosphoglycerate + P_i             ( DG^o = -49 kJ mol^-1)

         ADP + P_i ± ATP                                                                 (DG^o  = +31 kJ mol^-1)

        Which of the following concerning the above partial reactions is FALSE?

a)                  The energy change of the coupled reaction, or net reaction, is the sum of the energy  changes of the two partial reactions and DG^o is = -18 kJ mol^-1.

b)                 The coupled reaction is driven toward ATP, or occurs because the sum of the two free energy changes of the partial reactions is a negative value and yields energy to drive the reaction.

c)                  The overall reaction: 1,3-biphosphoglycerate + ADP ±  3-phosphoglycerate + ATP is endergonic; it requires +18 kJ and thus can not occur spontaneously.

d)                 The reactions occur during glycolysis.

e)                  ATP mediates the transfer of energy between exergonic reactions (that normally have relatively high free energies of phosphate transfer) and endergonic reactions.

44.                  Which statement is CORRECT? During aerobic respiration:

a)                  the energy for oxidative phosphorylation comes from ATP.

b)                 the energy to make ATP comes from the potential difference in proton concentration across the inner mitochondrial membrane.

c)                  ATP is made by the transport of protons through a series of oxidation-reduction reactions, resulting in the transfer of electrons across the crista membrane of the mitochondrion.

d)                 a mole of glucose may yield from 40 to 50 moles of ATP.

e)                  glucose is first converted to pyruvic acid in the mitochondrion.

45.                  Which statement about the Calvin cycle is FALSE?

a)                  CO₂ + 12 H₂O ±  C₆H₁₂O₆ + 6 O₂ + 6 H₂O

b)                 The five-carbon sugar ribulose bisphosphate is the acceptor molecule for CO₂.

c)                  Two molecules of phosphoglyceraldehyde (PGAL) combine to form one molecule of glucose.

d)                 Phosphoglycerate molecules are phosphorylated using ATP and then reduced to PGAL by NADPH.

e)                  ATP from mitochondrial respiration is used to fix carbon and produce phosphoglyceraldehyde (PGAL).

46.                  Many of the world's fisheries are severely depleted. The goal of sustainable harvesting in a fishery is to harvest only a constant proportion of the total population, for instance 30%. Unfortunately, the harvest size has often gone up or stayed constant even as the total population size has crashed. Here is simple model of a fishery: H = N x E x G H = harvest size (number of fish caught) N = total population size (number of fish) E = the harvest effort (the number of days spent fishing times the number of boats fishing; in other words, the units of E are boat-days) G = efficiency  (the proportion of N caught per boat per day) Which management approach is most sustainable and will NOT cause the population to crash in the long run?

a)                  As N decreases, increase G by using either sonar to find the fish more easily, nets  with smaller mesh sizes, or other advances in technology.

b)                 As N decreases, increase E by allowing more boats to fish or more days of fishing.

c)                  As N decreases, increase H.

d)                 As N decreases, set a level for H and keep it fixed at that level.

e)                  As N decreases, either E or G can change, but their product must remain constant.

47.             Which statement comparing the biochemical processes of photosynthesis and cellular respiration is FALSE?

a)                  Both biochemical processes take place in specialized organelles that have complex systems of internal membranes.

b)                 ATP synthesis in both processes relies on the chemiosmotic mechanism, involving the pumping of protons through a membrane.

c)                  Both processes involve the passing of electrons from carrier to carrier in a series of oxidation-reduction reactions which liberate energy.

d)                 The initial source of electrons which pass from carrier to carrier are from high-energy  food molecules in both processes.

e)                  Oxygen is an end-product of photosynthesis and carbon dioxide is an end-product of cellular respiration.

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