22. Evolution of Populations

Add labels to the figure that follows, which illustrates how Mycobacterium tuberculosis evolves when it is exposed to an antibiotic.

What is responsible for the increased stability of DNA compared to RNA?

Cooking oil lipids consist of long, unsaturated hydrocarbon chains. Would you expect these molecules to form membranes spontaneously? Why or why not? Describe, on a molecular level, how you would expect these lipids to behave in water.

In an area of erratic rainfall, a biologist found that grass plants with alleles for curled leaves reproduced better in dry years, and plants with alleles for flat leaves reproduced better in wet years. This situation would tend to _________ . (Explain your answer.)

a. Cause genetic drift in the grass population.

b. Preserve genetic variation in the grass population.

c. Lead to stabilizing selection in the grass population.

d. Lead to uniformity in the grass population.

If nucleotides from the DNA of a human were quantified and 30 percent of them contained the base adenine, what percentage of them would contain the base guanine?

a. 20 percent

b. 30 percent

c. 40 percent

d. 70 percent

If an allele is recessive and lethal in homozygotes before they reproduce,

a. The allele will be removed from the population by natural selection in approximately 1,000 years.

b. The allele will likely remain in the population at a low frequency because it cannot be selected against in heterozygotes.

c. The fitness of the homozygous recessive genotype is 0.

d. Both b and c are correct.

In the 1700s and 1800s, royalty in Europe often married their close relatives; furthermore, recessive genetic diseases such as hemophilia showed up much more often among royals than in the general population. Explain the likely connection.

Explain why continuous growth enhances the phenomenon known as phenotypic plasticity.

The heritable differences among organisms are a result of:

a. Differences in their DNA

b. Mutation

c. Differences in alleles

d. A and B are correct

e. A, B, and C are correct

According to the RNA world model, a ribozyme would replicate by creating a double-stranded RNA intermediate. Would you expect the intermediate to have the same catalytic activity as the original ribozyme? Justify your answer with an explanation.

A new plant species C, which formed from hybridization of species A(2n = 16) with species B(2n = 12), would probably produce gametes with a chromosome number of

a. 12.

b. 14.

c. 16.

d. 28.

Draw a small concept map showing how selection, genetic drift, gene flow, and mutation relate to genetic variation.

The risks faced by small populations include

a. Erosion of genetic variability through genetic drift

b. Decreased fitness of individuals as a result of inbreeding

c. Increased risk of experiencing natural disasters

d. A and B are correct

e. A, B, and C are correct

Ivory from elephant tusks is a valuable commodity on the world market. As a result, male African elephants with large tusks have been heavily hunted for the past few centuries. Today, male elephants have significantly shorter tusks at full adulthood than male elephants in the early 1900s. This is an example of:

a. Diversifying selection

b. Stabilizing selection

c. Directional selection

d. Chance

e. More than one of the above is correct

A horse (2n = 64) and a donkey (2n = 62) can mate and produce a mule. How many chromosomes would there be in a mule's body cells?

a. 31

b. 62

c. 63

d. 126