DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is that
a. Humans and chimpanzees share a relatively recent common ancestor.
b. Humans evolved from chimpanzees.
c. Chimpanzees evolved from humans.
d. Convergent evolution led to the DNA similarities.

Which of the following observations helped Darwin shape his concept of descent with modification?

a. Species diversity declines farther from the equator.

b. Fewer species live on islands than on the nearest continents.

c. Birds live on islands located farther from the mainland than the birds' maximum nonstop flight distance.

d. South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe.

Within six months of effectively using methicillin to treat S. aureus infections in a community, all new S. aureus infections were caused by MRSA. How can this best be explained?

a. A patient must have become infected with MRSA from another community.

b. In response to the drug, S. aureus began making drug- resistant versions of the protein targeted by the drug.

c. Some drug-resistant bacteria were present at the start of treatment, and natural selection increased their frequency.

d. S. aureus evolved to resist vaccines.

Which of the following is an observation or inference on which natural selection is based? (A) Individuals do not vary in their heritable characteristics. (B) Only well-adapted individuals produce offspring. (C) Species produce more offspring than the environment can support. (D) Nearly all of each individual's offspring will survive and reproduce.

A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from the air-breathing organ (a simple lung) of an ancestral fish is an example of

a. Exaptation.

b. Changes in Hox gene expression.

c. Paedomorphosis.

d. Adaptive radiation.

The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all three kinds of organisms diverged from a common ancestor at about the same time. Which of the following is the most likely explanation for these data?

a. Forelimb evolution was adaptive in people and bats, but not in whales.

b. Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy.

c. Genes mutate faster in whales than in humans or bats.

d. Whales are not properly classified as mammals.