Tut 14 - Natural selection _ Evolution

St Andrew’s Junior College Diversity & Evolution / Natural Selection & Evolution 2022 H1 Biology 1 Full Name: Civics group: 21S Index no.: Date: Biological Evolution Natural Selection and Evolution Tutorial 14 1 2 3 4 5 6 7 8 9 10 11 12 C B A C D A A B B C A A 1 A population of squirrels is preyed upon by small hawks. The smaller squirrels can escape into burrows. The larger squirrels can fight off the hawks. After several generations, the squirrels in the area tend to be very small or very large. What process is responsible for this outcome? A Stabilizing selection B Directional selection C Disruptive selection (conditions favor individuals at both extremes of a phenotypic range over individuals with intermediate phenotypes.) D Balancing selection 2 Birds with average sized wings survived a severe storm more successfully than other birds in the same population with longer or shorter wings. If severe storms occur regularly, then over time, one should expect these storms to bring about A the bottleneck effect B stabilizing selection extreme phenotypes are selected against C artificial selection E disruptive selection 3 Which type of selection maintains stable frequencies of two or more phenotypic forms in a population? A Balancing selection B Neutral variation C Heterozygote advantage D Stabilizing selection

St Andrew’s Junior College Diversity & Evolution / Natural Selection & Evolution 2022 H1 Biology 2 4 A number of mosquito populations today are resistant to insecticides that were once effective. Biologists think that insecticide resistance evolved in mosquitoes because A individual mosquitoes built up immunity to an insecticide after being exposed to it. B mosquitoes needed to develop insecticide resistance to survive after the insecticide was used. (development of insecticide resistance arose due to spontaneous mutation, not because of a need) C a few mosquitoes were probably resistant to the insecticide before it was ever used and these individuals were more likely to survive and reproduce. D use of insecticides induced mutations in mosquitoes, resulting in resistance to these insecticides (development of insecticide resistance arose due to spontaneous mutation. it is a random process and it is not something that can be controlled) Comment: Options A, B & D are indicative of Lamarck’s theory and hence are incorrect. 5 The diagram shows a form of selection operating within a population over three generations, 1, 2 and 3. Organisms in the shaded areas are selected against. What can be concluded from these results? A Loss of individuals with phenotypes close to the most common value suggests that the variation in the phenotypic characteristic has an environmental cause. (cannot tell, could be due to artificial selection) B One species is split, in three generations, i nto two species that are reproductively isolated from