BIO 148 Evolutionary Mechanisms Exam Questions With All Correct Answers Verified Answers 2025 Marking Scheme New Update

BIO 148 Evolutionary Mechanisms Exam Questions With All Correct Answers Verified Answers 2025 Marking Scheme New Update An earthquake decimates a ground-squirrel population. The surviving population happens to have broader stripes on average than the initial population. If broadness of stripes is genetically determined, what effect has the ground-squirrel population experienced during the earthquake? a. directional selection b. disruptive selection c. a founder event d. a genetic bottleneck e. gene flow - Answer- D Genetic drift occurs in a population. Which of the following statements might be true? a. Genetic drift increased the population's fitness. b. Genetic drift decreased the population's fitness. c. The population was relatively small. d. The population experiences a decrease in genetic variation. e. Any of the above statements might be true. - Answer- E In a particular species, female birds prefer to mate with males with the bluest feet. This is an example of _____________. - Answer- Sexual selection One group of fruit flies reproduces in August and one group reproduces in September. The reproductive isolating mechanism that prevents them from interbreeding is ____________. - Answer- Temporal isolation 5. The flowers of some salvia species can only be fertilized by large bumble bees. The flowers of other salvia species, however, are fertilized by small bees. The salvia species are reproductively isolated by ______________. - Answer- Mechanical isolation Usually, the first step leading to speciation of different populations is a. hybrid inviability b. adaptive radiation c. gene flow d. geographic isolation e. allopolyploidy - Answer- D The use of the Biological Species Concept in determining whether or not two genetically divergent populations should be regarded as different species is primarily focused on whether or not they A) are phenotypically different. B) each form a separate clade in a phylogenetic tree. C) are reproductively isolated. D) have important biological differences. E) none of the above. - Answer- C Within a population, genetic drift has the ultimate outcome of A) Increasing genetic variation. B) Increasing the frequency of the genotype with the highest fitness. C) Increasing the frequency of the genotype with the lowest fitness. D) Decreasing genetic variation. - Answer- D Quantitative traits are controlled by the inheritance of alleles at A) genes located on sex chromosomes. B) multiple genes C) a single gene D) genes only located on autosomes. - Answer- B Which of the following describes the most likely order of events in speciation? A) divergence, genetic isolation B) genetic isolation, divergence - Answer- B 12. Which of the following are important in the prezygotic isolation of two different biological species? A) gametic barriers B) hybrid inviability C) mechanical isolation D) A and B E) A and C - Answer- E Vestigial characters and DNA mutations that do not change the translated amino acid are good examples of A) adaptation B) nothing, absolutely nothing C) convergent traits D) neutral traits E) developmental homology - Answer- D Currently the only predators of Galápagos marine iguanas are Galápagos hawks. Iguana body size is not correlated with risk of hawk predation, although small iguanas can sprint faster than large iguanas. If predators (e.g., cats) that preferably catch and eat slower iguanas are introduced to the island, iguana body size is likely to _____ in the absence of other factors; the iguanas would then be under _____ selection. a. increase; directional b. increase; disruptive c. decrease; directional d. decrease; disruptive e. stay the same; stabilizing - Answer- C Initially incomplete isolating mechanisms can be reinforced by natural selection until they are completely effective (a process called reinforcement). works against reinforcement a. Gene flow b. Speciation c. Reproductive Isolation d. Disruptive selection - Answer- A What is the ultimate source of new alleles in a population? a. Mutation b. Sexual Reproduction c. Crossing over during meiosis d. All of the above. - Answer- A