A.   The finches had gone extinct from the islands due to volcanic activity.

B.   The finches had the same beak sizes and shapes as the mainland finches.

C.   The finches had beaks of different sizes and shapes that were suited to the available food.

D.   All of the finches looked exactly the same regardless of the island they came from.

A.   The tortoises Darwin noticed on the Galapagos Islands that had developed different sized necks based on selective pressures from the environment.

B.   The finches that Darwin noticed on the Galapagos Islands that had developed different shaped beaks based on selective pressures from the environment.

C.   The pigeons Darwin noticed that had traits such as reverse neck feathers that had been selectively bred by humans.

D.   The fossils that Darwin noticed from huge animals like Glyptodon, a giant armadillo, that looked very much like living species.

A.   Adaptation

B.   Uniformitarianism

C.   Variation

D.   Descent with modification

A.   Geographical distribution of organisms

B.   The fossil record

C.   Anatomical structures

D.   All of these

A.   A snake tail and a monkey tail

B.   A bat wing and an insect wing

C.   A dolphin fin and a shark fin

D.   A human hand and a cat paw

A.   A population is completely wiped out due to disease.

B.   Immigration of individuals into a large population, causing the population size to increase even further.

C.   A volcano erupts on an island leaving only a few survivors in a population.

D.   A large population that continues to grow exponentially.

A.   Male bighorn sheep compete by butting heads and the winner of the competition gets to mate with the female.

B.   Male widowbirds who have longer tail feathers tend to be more attractive to female widowbirds, so they have more reproductive success than those with shorter tail feathers.

C.   Male frigate birds who inflate the air sac in their chest to attract females.

D.   Male jaguars with large jaws and teeth that can eat shelled reptiles, which makes them more likely to survive and to have more offspring than jaguars that can eat only mammals.

A.   Genetic drift

B.   Hardy-Weinberg equilibrium

C.   Natural selection

D.   Sexual selection

A.   Become separated, but can still interbreed to produce fertile offspring

B.   Interbreed

C.   Become reproductively isolated

D.   Become extinct