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EvoPset1Questions2013

D the advent of mendelian genetics helped lead to the

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D. The advent of Mendelian genetics helped lead to the notion that infinite population size, as well as random mating and an absence of migration, is necessary for selection to occur. Reset Selection Mark for Review What's This? Question 15 of 22 4.0 Points In a species of hermaphroditic snails with non-overlapping generations, shell color is controlled by a single gene with two alleles. Snails that are homozygous for one allele have yellow shells, those homozygous for the other allele have blue shells, and heterozygotes have green shells. You observe that in a nearly endless expanse of snails, 175 million are yellow, 50 million are green, and 25 million are blue (you are very good at counting). If there follows one generation of random mating within the population, how many green snails would you expect to see in the next generation if the population size is the same and there is no selection on shell color? A. 0 B. 4 million C. 32 million D. 40 million E. 50 million F. 80 million
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4/5/13 8:17 PM 2013 Problem Set 1 on Evolution Lectures 1-3 Page 6 of 8 https://coursework.stanford.edu/portal/tool/1c2f43e9-1653-4e97-98f7-93a4fbb2cb09/jsf/delivery/beginTakingAssessment G. 175 million H. The number cannot be estimated Reset Selection Mark for Review What's This? Question 16 of 22 4.0 Points In this same population of snails, if instead of random mating the blue snails only mate with each other, how will this affect the fraction of blue snails in the next generation? A. it will increase B. it will decrease C. it will not change D. need more information Reset Selection Mark for Review What's This? Question 17 of 22 4.0 Points Why is natural selection for HIV resistance an unlikely explanation for worldwide patterns of CCR5-D32 allele frequency? Choose ALL that apply: A. The HIV epidemic is too recent to have caused noticeable frequency changes. B. Both CCR5-D32 allele frequency and HIV incidence are low in China. C. HIV should have driven the allele to fixation in all populations. D. The pattern for CCR5-D32 does not match the expectation based on the pattern for HIV prevalence. E. Individuals heterozygous for the wildtype CCR5 allele and the CCR5-D32 deletion are extra-susceptible to HIV and AIDS. Mark for Review What's This? Question 18 of 22 4.0 Points In 2008, Stanford researchers published a study of 11 Oceanic cultures describing how natural selection acted on canoe designs. They suggested that natural selection was weeding out inferior designs of functional elements. Which of the following observations would constitute the prerequisites for natural selection in this system? Pick ALL that apply: A. The canoes of some Oceanic cultures must have been superior to those of others B. Canoes can vary in functional features C. Poorly-designed canoes must have sank, along with the individuals who designed them D. Individuals learn how to build canoes based on past designs E. Some canoes are considered better than others by the canoe builders F. The canoes must have been built out of wood or other biological materials
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D The advent of Mendelian genetics helped lead to the...

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