Chapter 20 - Summative Quiz

In a population at Hardy-Weinberg equilibrium with only two alleles at locus A, the frequency of A alleles is 0.1. The frequency of heterozygotes for this allele is 0.50. 0.09. 0.01. 0.18. 0.02.

0.18

In a hypothetical population of gazelles, 28 individuals are homozygous for the d2 allele, 72 individuals are heterozygous for the d2 allele, and 100 individuals lack the d2 allele. What is the frequency of the d2 allele? 0.68 0.64 0.25 0.32 0.50

0.32

Assuming there are only two alleles at a given locus, if the frequency of one allele is 0.3, what is the frequency of the other allele? 0.7 0.5 -0.3 0.3 0

0.7

A population of beavers has 135 individuals that are homozygous for one allele, 230 that are heterozygous, and 135 that are homozygous for the other allele. Compared with Hardy-Weinberg expectations, this population has _______ too _____ heterozygotes. 20; many 50; many 10; few 10; many 20; few

20; few

Next-generation sequencing reveals that six new mutations have occurred in the coding regions of genes in an individual diploid fly. If the coding regions of this fly comprise 100 million nucleotides per haploid genome, what is the mutation rate per nucleotide? A. 15 per billion B. 30 per billion C. 60 per billion D. 15 per million E. 3 per billion

30 per billion

Under which condition is Hardy-Weinberg equilibrium not applicable? Zero mutation Large population size An evolving population No gene flow into or out of the population Random mating

An evolving population

There are two isolated populations (A and B) of an endangered plant species. Population A has had a constant size of 2,000 plants, and population B has had a constant size of 250 plants. We most expect to see an increase in the frequency of deleterious alleles in population _______ due to _______. A. B; genetic drift B. B; positive selection C. A; genetic drift D. A; positive selection E. B; purifying selection

B; genetic drift

Had Wallace died before sending a letter to Darwin, which circumstance would be most likely? A. Darwin would have published his evolutionary theory later than he did. B. Darwin's evolutionary theory would not have considered descent with modification. C. Darwin would not have stressed gradual change in his theory. D. Darwin's evolutionary theory would not have incorporated natural selection. E. Darwin would not have known about animal and plant breeding.

Darwin would have published his evolutionary theory later than he did.

In a plant population, the genotypes that grow fastest tend to be the most sensitive to drought. This is an example of _______, and it tends to _______ evolution. a trade-off; accelerate stabilizing selection; accelerate disruptive selection; accelerate a trade-off; constrain disruptive selection; constrain

a trade-off; constrain

Snapping shrimp have evolved very rapid movements in the structures they use to capture prey. These rapid movements, which evolved through natural selection, can be considered a(n) _______, and the process by which they evolved is called _______. A. adaptation; adaptation B. phenotype; purifying selection C. founder effect; purifying selection D. founder effect; adaptation E. adaptation; purifying selection

adaptation; adaptation

A neutral allele can accumulate in populations. is not affected by genetic drift. is affected by natural selection. cannot be detected at the molecular level. can lead to a discernible phenotype.

can accumulate in populations

Sexual recombination changes the frequency of alleles in a population. can result in the elimination of harmful mutations. decreases the variety of genetic combinations. increases the overall reproductive rate. has no influence on evolution.

can result in the elimination of harmful mutations.

Evolution is most likely to be constrained by developmental processes. sexual dimorphism. environmental variation. genetic diversity. neutral alleles.

developmental processes

Alleles are A. units of natural selection. B. genotypes. C. heritable traits. D. different forms of a gene. E. phenotypes.

different forms of a gene

Shown is a table of the results of a study of grasshoppers showing frequencies of different size classes, along with the average number of offspring these individuals produce. SIZE FREQUENCY OFFSPRING 2.5-0.9 0.19 37 3.0-3.4 0.26 29 3.5-3.9 0.28 24 4.0-4.4 0.21 19 4.5-5.0 0.06 7 Assuming that size is a heritable trait (and that the number of offspring is a good proxy for the fitness of the phenotype), which type of selection is operating in this population? Stabilizing selection Intersexual Directional selection for larger individuals Directional selection for smaller individuals Disruptive

directional selection for smaller individuals

In a population of mice, the average survival rates of individuals of varying sizes were assayed and are shown in the table. BODY WEIGHT SURVIVAL RATE more than 50g 0.59 45-50g 0.55 40-45g 0.52 35-40g 0.42 under 35g 0.38 Assume that body size is at least partially heritable. Assuming that all other aspects are independent of size, this population is most likely experiencing ______ selection, and the variation in the population should _______over many generations. stabilizing; increase diversifying; increase directional; decrease directional; increase stabilizing; decrease

directional; decrease

Allele frequencies can be used to measure the _______ of a Mendelian population, whereas _______ show(s) how it is/they are distributed among the population's members. A. genetic variation; genotype frequencies B. polymorphisms; genotype frequencies C. genotype frequencies; genetic structure D. genotype frequencies; genetic variation E. genetic structure; genotype frequencies

genetic variation; genotype frequencies

In a species of beetles, males that have large horns are better able to fight off other males for access to females. This is an example of _______ selection. intrasexual stabilizing disruptive intersexual purifying

intrasexual

The table shows the number of offspring produced by individuals of three genotypes at the B locus in five different populations POPULATION BB Bb bb 1 36 56 79 2 76 99 104 3 21 35 28 4 56 43 67 5 23 34 45 Assuming survival rates and all other factors are equal across genotypes, in which population would you most likely expect variation at the B locus to be maintained? Population 4 Population 5 Population 2 Population 3 Population 1

population 3

Individual females within a population of horses are tracked over time to examine their reproductive output. The researchers find that females with the smallest and largest body sizes have fewer offspring than females of average body size. Most likely, _______ selection for size is operating. sexual diversifying directional destabilizing stabilizing

stabilizing