2016年AP生物简答题真题PDF下载
1. Leucine aminopeptidases(LAPs) are found in all living organisms and have been associated with the response of the marine mussel, Mytilus edulis, to changes in salinity. LAPs are enzymes that remove N-terminal amino acids from proteins and release the free amino acids into the cytosol. To investigate the evolution of LAPs in wild populations of M. edulis, researchers sampled adult mussels from several different locations along a part of the northeast coast of the United States, as shown in Figure 1. The researchers then determined the percent of individuals possessing a particular lap allele, lap94, in mussels from each sample site (table 1).
(a) On the axes provided, construct an appropriately labeled bar graph to illustrate the observed frequencies of the lap94 allele in the study populations.
(b) Based on the data, describe the most likely effect of salinity on the frequency of the lap94 allele in the marine mussel populations in Long Island Sound. Predict the likely lap94 allele frequency at a sampling site between site 1 and site 2 in Long Island Sound.
(c) Describe the most likely effect of LAP94 activity on the osmolarity of the cytosol. Describe the function of LAP94 in maintaining water balance in the mussels living in the Atlantic Ocean.
(d) Marine mussel larvae are evenly dispersed throughout the study area by water movement. As larvae mature, they attach to the rocks in the water. Explain the differences in lap94 allele frequency among adult mussel populations at the sample sites despite the dispersal of larvae throughout the entire study area. Predict the likely effect on distribution of mussels in Long Island Sound if the lap94 allele was found in all of the mussels in the population. Justify your prediction.
2. Bacteria can be cultured in media with a carefully controlled nutrient composition. The graph above shows the growth of a bacterial population in a medium with limiting amounts of two nutrients, I and II.
(a) Estimate the maximum population density in cells/mL for the culture. Using the data, describe what prevents further growth of the bacterial population in the culture.
(b) Using the data, calculate the growth rate in cells/mL×hour of the bacterial population between hours 2 and 4.
(c) Identify the preferred nutrient source of the bacteria in the culture over the course of the experiment. Use the graph to justify your response. Propose ONE advantage of the nutrient preference for an individual bacterium.
(d) Describe how nutrient I most likely regulates the genes for metabolism of nutrient I and the genes for metabolism of nutrient II. Provide TWO reasons that the population does not grow between hours 5 and 6.
3. The graph above illustrates the percent dry weight of different parts of a particular annual plant (plants that live less than one year) from early May to late August. The percent dry weight can be used to estimate the amount of energy a plant uses to produce its leaves, vegetative buds, stems, roots, and reproductive parts (seeds, receptacles, and flowers).
(a) Identify the direct source of the energy used for plant growth during the first week of May, and identify the part of the plant that grew the most during the same period.
(b) Based on the data on the graph, estimate the percent of the total energy that the plant has allocated to the growth of leaves on the first day of July.
(c) Compared with perennials (plants that live more than two years), annual plants often allocate a much greater percentage of their total energy to growth of their reproductive parts in any given year. Propose ONE evolutionary advantage of the energy allocation strategy in annual plants compared with that in perennial plants.
2016年AP生物简答题真题余下省略！
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