Biology Chapter 19

How can evolutionary biologists use Hardy-Weinberg equilibrium while studying populations of organisms that they suspect may be evolving? A. Scientists can tell a population is evolving if the allele frequencies change. B. Scientists can tell a population is evolving if the genotype frequencies are constant. C. Scientists can tell a population is evolving if the frequencies of homozygous dominant and homozygous recessive individuals are not equal. D. Scientists can tell a population is evolving if the frequencies of homozygous dominant and homozygous recessive individuals are equal.

A. Scientists can tell a population is evolving if the allele frequencies change.

Stabilizing selection _____. A. favors intermediate variants in a population B. prevents mutations from occurring C. occurs when some individuals migrate to an area with different environmental conditions D. can take place only in species exhibiting sexual dimorphism E. occurs only in plants

A. favors intermediate variants in a population

What is the evolutionary mechanism that alters allele frequencies by chance called? A. genetic drift B. inbreeding C. migration

A. genetic drift

What is the ultimate source of all variation in and among populations? A. genetic mutations that result in viable offspring B. natural selection C. diverse habitats D. factors in the environment that may affect development

A. genetic mutations that result in viable offspring

Population genetics is the study of: A. how selective forces change the allele frequencies in a population over time B. the genetic basis of population-wide traits C. whether traits have a genetic basis D. the degree of inbreeding in a population

A. how selective forces change the allele frequencies in a population over time

Population variation is not only influenced by genes. Give an example of variation caused by environment factors. A. Fish and whales have similar body shapes because of their aquatic environment, despite not sharing a recent common ancestor. B. In organisms such as alligators and other reptiles, the gender of the individuals is determined by the temperature at which the eggs are incubated. C. In a certain species of moth, black wing color was selected for over speckled wing color because an increase in smoke from coal-burning factories made the environment darker over a very short period of time. D. Human skin cells often become cancerous upon exposure to UV radiation from the environment.

B. In organisms such as alligators and other reptiles, the gender of the individuals is determined by the temperature at which the eggs are incubated

Antibiotics are medicines that are designed to kill disease-causing organisms, or pathogens. However, some pathogens evolve antibiotic resistance, where they gain traits that allow them to survive in the presence of antibiotics. The ability of bacteria to adapt to antibiotics so quickly has created a huge concern over whether antibiotics are being overused. What form of evolution is antibiotic resistance an example of, and why? A. Gene flow because the bacteria are passing on the resistant trait within their populations. B. Natural selection, because the bacteria is adapting to a new environmental condition - the presence of the antibiotic. C. Genetic drift because medical workers cannot follow the randomly-fluctuating gene frequencies of bacterial populations D. Mutation, because each bacteria must mutate to an antibody resistant form in order to survive.

B. Natural selection, because the bacteria is adapting to a new environmental condition - the presence of the antibiotic.

When imbalances occur in the sex ratio of sexual species that have two sexes (i.e., other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of A. sexual selection. B. frequency-dependent selection. C. stabilizing selection. D. disruptive selection. E. balancing selection.

B. frequency-dependent selection.

What is the difference between micro- and macroevolution? A. Microevolution describes the evolution of small organisms, such as insects, while macroevolution describes the evolution of large organisms, like people and elephants. B. Microevolution describes the evolution of microscopic entities, such as molecules and proteins, while macroevolution describes the evolution of whole organisms. C. Microevolution describes the evolution of organisms in populations, while macroevolution describes the evolution of species over long periods of time. D. Microevolution describes the evolution of organisms over their lifetimes, while macroevolution describes the evolution of organisms over multiple generations.

C. Microevolution describes the evolution of organisms in populations, while macroevolution describes the evolution of species over long periods of time.

Blue poppies native to China were grown at a plant-breeding center in California. The plants with the thickest leaves were most likely to survive and reproduce in the drier climate. This adaptation of the poppies to their new environment is due to _____. A. genetic drift B. stabilizing selection C. directional selection D. neutral variation E. disruptive selection

C. directional selection

Longer tails of male barn swallows evolve because female barn swallows prefer to mate with the males that have the longest tails. This process is best described as A. genetic drift that changes the frequencies of the alleles for tail length. B. natural selection for sexual reproduction that maintains variation in the genes that influence tail length. C. intersexual selection for traits, such as long tails, that help males attract mates. D. intrasexual selection for traits, such as long tails, that help males win contests for females. E. directional selection for traits, such as long tails, that improve males' ability to fly strongly and forage for food over large areas.

C. intersexual selection for traits, such as long tails, that help males attract mates.

The evolutionary effects of genetic drift are greatest when _____. A. the population size is large B. intraspecific competition is intense C. the population size is small D. intraspecific competition is weak E. sexual selection occurs

C. the population size is small

In a certain group of African people, 4% are born with sickle-cell disease (homozygous recessive) . If this group is in Hardy-Weinberg equilibrium, what percentage of the group has the selective advantage of being more resistant to malaria (heterozygous) than those individuals who are homozygous for normal hemoglobin or for sickle-cell disease? A. 2% B. 4% C. 8% D. 16% E. 32%

E. 32%

What is the term for a change in the relative frequencies of alleles in a population from generation to generation? A. gene pool B. independent assortment C. macroevolution D. reservoir E. microevolution

E. microevolution

In the Hardy-Weinberg theorem, p2 represents _____. A. the total alleles in the gene pool B. the frequency of heterozygous dominants in the gene pool C. the frequency of homozygous recessives in the gene pool D. all of the possible phenotypes in the gene pool E. the frequency of homozygous dominants in the gene pool

E. the frequency of homozygous dominants in the gene pool