Question 1

Which of the following is NOT a requirement for a population to be in Hardy-Weinberg equilibrium?

Accepted Answer

Natural selection is actively favoring certain alleles.

Question 2

A population of 1,000 butterflies has two alleles for wing color: B (dominant, blue) and b (recessive, brown). If 360 butterflies are brown (bb), what is the frequency of the b allele in the population? Use the Hardy-Weinberg equation.

Accepted Answer

$$q = 0.6$$

Question 3

Which scenario best illustrates the founder effect?

Accepted Answer

A small group of lizards colonizes a new island, carrying only a subset of the genetic diversity from the original population.

Question 4

Which of the following is an example of disruptive selection?

Accepted Answer

A population of finches evolves both large and small beak sizes, but medium beak sizes become rare.

Question 5

Which process is the only one that consistently leads to adaptive evolution?

Accepted Answer

Natural selection

Question 6

In a population, the frequency of allele A is $$p = 0.7$$ and the frequency of allele a is $$q = 0.3. $$According to Hardy-Weinberg equilibrium, what is the expected frequency of heterozygotes (Aa)?

Accepted Answer

$$2pq = 0.42$$

Question 7

Which of the following best describes gene flow?

Accepted Answer

The movement of alleles between populations due to migration of fertile individuals.

Question 8

A population of fish is exposed to a pollutant that kills individuals with a certain genotype. Over time, the population becomes less genetically diverse. Which evolutionary mechanism is most likely responsible for this loss of genetic variation?

Accepted Answer

Genetic drift

Question 9

Which of the following is an example of frequency-dependent selection?

Accepted Answer

A fish species where the fitness of a scale-eating morph depends on how common it is in the population.

Question 10

Which of the following preserves genetic variation in a population?

Accepted Answer

Diploidy

Question 11

A population of 500 mice has two alleles for fur color: G (gray, dominant) and g (white, recessive). If the frequency of the G allele is $$p = 0.8$$, what is the expected frequency of white mice (gg) under Hardy-Weinberg equilibrium?

Accepted Answer

$$q^2 = 0.04$

Question 12

Which of the following is a consequence of the bottleneck effect?

Accepted Answer

A sudden reduction in population size leading to loss of genetic diversity

Question 13

Which type of selection is most likely to result in sexual dimorphism?

Accepted Answer

Sexual selection

Question 14

In a population, individuals who are heterozygous for a particular gene have higher fitness than either homozygote. This is an example of:

Accepted Answer

Heterozygote advantage

Question 15

Which of the following best describes gene variability?

Accepted Answer

The percentage of population loci that are heterozygous.

Question 16

A population of plants has two alleles for flower color: R (red) and r (white). If $$p = 0.5$$ and $$q = 0.5$$, what is the expected proportion of red-flowered plants (RR or Rr) under Hardy-Weinberg equilibrium?

Accepted Answer

$$p^2 + 2pq = 0.75$

Question 17

Which of the following is an example of non-heritable variation?

Accepted Answer

A suntan acquired after exposure to sunlight

Question 18

Which of the following is a real-world example of gene flow?

Accepted Answer

A population of blue-eyed people moves to a small town in Mexico where only brown eyes were present.

Question 19

Which of the following statements about genetic drift is TRUE?

Accepted Answer

It can cause harmful alleles to become fixed in a population.

Question 20

Which of the following best explains why recessive alleles can persist in a population even if they are not currently advantageous?

Accepted Answer

Diploidy allows recessive alleles to be hidden in heterozygotes.

ch 23 Population Genetics and the Evolution of Populations

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