BIOL 1407 Chapter 20 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

0.18

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?

0.32

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

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; 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?

30 per billion

Under which condition is Hardy-Weinberg equilibrium not applicable?

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 _______.

B; genetic drift

Had Wallace died before sending a letter to Darwin, which circumstance would be most likely?

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

15). 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. 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?

Directional selection for smaller individuals

18). The table shows the number of offspring produced by individuals of three genotypes at the B locus in five different populations. 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 3

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; 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 _______.

adaptation; adaptation

A neutral allele

can accumulate in populations.

Sexual recombination

can result in the elimination of harmful mutations.

Evolution is most likely to be constrained by

developmental processes.

Alleles are

different forms of a gene.

13). In a population of mice, the average survival rates of individuals of varying sizes were assayed and are shown in the table. 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.

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.

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

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.

stabilizing