Q: Relative fitness is a key concept in natural selection. Which equation correctly represents the calculation of relative fitness ($$w) $$for a genotype?

$$w = \frac{\text{number of offspring produced by genotype}}{\text{average number of offspring in population}}$$

Question 1

Which of the following best describes the role of chance in evolution by natural selection?

Accepted Answer

Chance creates new genetic variation, but natural selection sorts these variations based on reproductive advantage.

Question 2

Relative fitness is a key concept in natural selection. Which equation correctly represents the calculation of relative fitness ($$w) $$for a genotype?

Accepted Answer

$$w = \frac{	ext{number of offspring produced by genotype}}{	ext{average number of offspring in population}}$$

Question 3

A population of mice lives in an environment with both light and dark rocks. Over time, the population evolves to have more individuals with intermediate fur coloration. Which mode of selection is most likely occurring?

Accepted Answer

Stabilizing selection

Question 4

In a population of scale-eating fish, the frequency of left-mouthed individuals rises and falls in a regular manner. This is an example of:

Accepted Answer

Frequency-dependent selection

Question 5

Which of the following scenarios best illustrates balancing selection?

Accepted Answer

A population maintains two alleles for a gene because heterozygotes have higher fitness than either homozygote.

Question 6

Sickle-cell disease is maintained in some populations due to heterozygote advantage. What is the genotype of a heterozygote for the sickle-cell allele?

Accepted Answer

$$AS$$

Question 7

Which of the following is an example of sexual selection through intersexual selection?

Accepted Answer

Female peahens choosing males with the most elaborate tail feathers.

Question 8

A population of finches experiences a drought, and only those with larger beaks survive to reproduce. Which type of selection is this?

Accepted Answer

Directional selection

Question 9

Which equation best represents the Hardy-Weinberg equilibrium for allele frequencies in a population?

Accepted Answer

$$p^2 + 2pq$$ + $$q^2 = 1$

Question 10

Why does frequency-dependent selection help maintain genetic diversity in a population?

Accepted Answer

It alternately favors rare phenotypes, preventing any one phenotype from becoming fixed.

Question 11

Which of the following adaptations is an example of a complex trait that evolved for a new function, rather than a simple modification of an existing trait?

Accepted Answer

Bird wings evolving from forelimbs originally used for walking.

Question 12

Which statement best explains why natural selection does not produce 'perfect' organisms?

Accepted Answer

Evolution is limited by historical constraints and trade-offs between adaptations.

Question 13

In a population of peacocks, males with the most elaborate tails are more likely to mate. This is an example of:

Accepted Answer

Intersexual selection

Question 14

Which of the following is a real-world example of disruptive selection?

Accepted Answer

Finches with either very large or very small beaks survive better than those with intermediate beak sizes.

Question 15

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

Accepted Answer

Individuals must have equal reproductive success

Question 16

A population of snakes evolves movable jaw bones that allow them to eat larger prey. This adaptation is most likely the result of:

Accepted Answer

Natural selection favoring individuals with greater jaw flexibility

Question 17

Which of the following best describes the concept of 'good genes' in sexual selection?

Accepted Answer

Females choose mates based on traits that indicate high genetic quality.

Question 18

In a population of scale-eating fish, the frequency of left-mouthed individuals in 1981 was 0.5, in 1987 was 0.2, and in 1990 was 0.8. What does this pattern suggest?

Accepted Answer

Frequency-dependent selection, where the rare phenotype is favored

Question 19

Which of the following is an example of an adaptation that is a compromise between competing functions?

Accepted Answer

A seal's flipper is good for swimming but not for walking on land.

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