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Exam 1 2010 Answer Key - BIO 171 Exam 1 Winter 2010...

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1 BIO 171 Exam 1 Winter 2010 Multiple Choice Answer Key FORM 1 d,d,a,b,e,b,b,b,c,a,c,a,d,d,c,a,d,e,e,d,b,c,a,d,e,b,c,b,a,e FORM 2 e,b,b,b,c,d,d,a,b,a,c,a,d,d,c,a,d,e,b,c,a,d,e,c,b,a,e,e,d,b FORM 3 e,d,b,c,b,a,e,a,c,a,d,d,e,b,b,b,c,c,a,d,e,b,c,a,d,e,d,d,a,b Short answer key starts on next page
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2 SHORT ANSWER QUESTIONS: You MUST answer ONLY 4 of these questions. Draw an X through the Q you are choosing not to answer. SA1 . Bison are large herbivores that live in prairies in the mid-western and western states of the USA. Prairies are grassland communities with a diversity of plant species including a diversity of grasses, herbs and flowering plants. Prairies where bison are absent have low biodiversity and are dominated by a species of tall grass. Some biologists hypothesize that bison are a keystone species. (10 pts total, parts A through D) A) Define what a keystone species is (1) and explain why it is important in community dynamics (1). A keystone species is a species whose presence has a large impact on the species composition of the community. The impact of the keystone species is much larger than predicted by its abundance or its biomass (its impact is disproportional to its abundance). B) Design an experiment that will let you test the hypothesis that bison are keystone species (2). Be sure to include replication, an appropriate control, and explain what you will measure (2). If bison are keystone species, then their presence should have a large impact on the species composition in the prairie community. The easiest way to test this is to remove bison from some areas of prairie and allow them to remain in other prairie areas. Treatment group = remove all bison from 30 plots of prairie (plots should be a large area, maybe 100 m 2 ), then fence plots to keep bison out Control group = 30 plots of prairie (same size as treatment plots) NOT fenced, such that bison have access We run the experiment for a long period of time (a whole plant growing season, a year, or multiple years). We would measure all the species of plants found in experimental plots and control plots at the beginning of the experiment and compare these to experimental and control plants at the end of the experiment. We also could measure the abundance of each species and compare this between the treatment plots and the control plots. C) Which two abiotic factors influence the global distribution of prairies and other grasslands on Earth? (2) temperature and rainfall patterns D) Why is identifying keystone species an important part of conservation efforts? (2) If we knew the identity of a keystone species in most communities, then we could design our conservation efforts around the requirements for the keystone species and therefore preserve dozens of other species at the same time.
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