CLEP - Biology Mechanisms of Natural Selection Questions and Answers

Question 1

In a population of birds, individuals with very small beaks and individuals with very large beaks are better able to find food than individuals with medium-sized beaks.
Over time, this results in a population with a higher frequency of birds with either very small or very large beaks.
Which pattern of natural selection does this scenario describe?

Accepted Answer

Disruptive selection

Answer

Stabilizing selection

Answer

Directional selection

Answer

Sexual selection

Question 2

Which of the following best defines evolutionary 'fitness'?

Accepted Answer

The ability of an organism to survive and reproduce in its environment.

Answer

The physical strength and health of an individual.

Answer

The lifespan of an organism compared to others in its population.

Answer

The complexity of an organism's adaptations.

Question 3

A population of peppered moths experiences a change in its environment when industrial pollution causes trees to become darkened with soot. As a result, the frequency of the dark-colored moth phenotype increases, while the light-colored phenotype becomes rare. This is a classic example of:

Accepted Answer

Directional selection

Answer

Genetic drift

Answer

Disruptive selection

Answer

Stabilizing selection

Question 4

A sudden volcanic eruption drastically reduces the size of a beetle population. The surviving beetles have a different allele frequency by chance than the original population. This event is an example of:

Accepted Answer

The bottleneck effect

Answer

Gene flow

Answer

Natural selection

Answer

Sexual selection

Question 5

In a stable environment, human babies with an average birth weight are more likely to survive than babies who are born much smaller or much larger. This is an example of what mechanism of natural selection?

Accepted Answer

Stabilizing selection

Answer

Disruptive selection

Answer

Directional selection

Answer

The founder effect

Question 6

Which of the following is NOT a condition required for natural selection to occur?

Accepted Answer

A tendency towards perfection in the population.

Answer

Variation in traits within a population.

Answer

Traits that are heritable.

Answer

Differential survival and reproduction.