Bio Ch 13 Test Review Part 2/2

Large antlers in male elk, which are used for battles between males, are a good example of a trait favored by

• intersexual selection

• directional selection

• disruptive selection

• intrasexual selection

The ultimate source of all new alleles is

• mutation.

• genetic drift.

• chromosomal duplication.

• natural selection.

Which term represents the frequency of heterozygotes in a population that is in Hardy-Weinberg equilibrium?

Imagine that you are studying a very large population of moths that is isolated from gene flow. A single gene controls wing color. Half of the moths have white-spotted wings (genotype WW or Ww), and half of the moths have plain brown wings (ww). There are no new mutations, individuals mate randomly, and there is no natural selection on wing color. How will p, the frequency of the dominant allele, change over time?

• p will neither increase nor decrease; it will remain more or less constant under the conditions described.

• p will decrease because of genetic drift.

• p will fluctuate rapidly and randomly because of genetic drift.

• p will increase; the dominant allele will eventually take over and become most common in the population.

Microevolution, or evolution at its smallest scale, occurs when

• a new species arises from an existing species.

• a population's allele frequencies change over a span of generations.

• an individual's traits change in response to environmental factors.

• a community of organisms changes due to the extinction of several dominant species.

The allele for cystic fibrosis is recessive. For this gene among Caucasians, p = 0.98. If a Caucasian population is in Hardy-Weinberg equilibrium with respect to this gene, what proportion of babies is born homozygous recessive and therefore suffers cystic fibrosis?

Genetic drift resulting from a disaster that drastically reduces population size is called ___.

In populations of the greater prairie chicken in Illinois, genetic diversity was lost through

• genetic drift and restored by natural selection.

• mutation and restored by natural selection.

• gene flow and restored by mutation.

• genetic drift and restored by gene flow.

A population of 1,000 birds exists on a small Pacific island. Some of the birds are yellow, a characteristic determined by a recessive allele. The others are green, a characteristic determined by a dominant allele. A hurricane on the island kills most of the birds from this population. Only 10 remain, and those birds all have yellow feathers. Which statement is true about this situation?

• Assuming that no new birds come to the island and no mutations occur, future generations of this population will contain both green and yellow birds.

• The hurricane has caused a population bottleneck and a loss of genetic diversity.

• The 10 remaining birds will mate only with each other, and this will contribute to gene flow in the population.

• This situation illustrates the effect of a mutation event occurring after genetic drift.

Thirty people are selected for a long-term mission to colonize a planet many light-years away from Earth. The mission is successful, and the population rapidly grows to several hundred individuals. However, certain genetic diseases are unusually common in this group, and the group's gene pool is quite different from that of the Earth population they have left behind. Which phenomenon has left its mark on this population?