Q: In a population of 750 rabbits, the frequency of the black fur allele (A) is 0.827 and the white fur allele (a) is 0.173. What is the expected frequency of heterozygotes (Aa) under Hardy-Weinberg equilibrium?

$$2pq = 2 \times 0.827 \times 0.173 = 0.286$$

Question 1

Which of the following best describes Darwin's first postulate of natural selection?

Accepted Answer

There is variation among individuals in a population.

Question 2

In a population of salmon, some individuals are faster swimmers and some are slower. According to Darwin's postulates, what must be true for natural selection to act on swimming speed?

Accepted Answer

Swimming speed must be heritable.

Question 3

A population of fruit flies is allowed to mate randomly for several generations, and a white fruit fly appears. Which evolutionary mechanism is responsible for this new phenotype?

Accepted Answer

Mutation

Question 4

Which equation is used to calculate allele frequencies in a population under Hardy-Weinberg equilibrium?

Accepted Answer

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

Question 5

In a population of 750 rabbits, the frequency of the black fur allele (A) is 0.827 and the white fur allele (a) is 0.173. What is the expected frequency of heterozygotes (Aa) under Hardy-Weinberg equilibrium?

Accepted Answer

$$2pq = 2 	imes 0.827 	imes 0.173 = 0.286$$

Question 6

Which pattern of natural selection is most likely to result in two distinct groups within a population, each with high fitness at opposite extremes of a trait?

Accepted Answer

Disruptive selection

Question 7

If a population is not in Hardy-Weinberg equilibrium, which of the following could be a possible cause?

Accepted Answer

Gene flow is introducing new alleles.

Question 8

A population of fruit flies is subjected to a selection pressure that gives white fruit flies a 10% advantage. After several generations, only black fruit flies from another population are allowed to immigrate. Which mechanisms of evolution are acting in this scenario?

Accepted Answer

Directional selection and gene flow

Question 9

Which of the following is the only source of new genetic variation in a population?

Accepted Answer

Mutation

Question 10

In a population of 500 rabbits, 32 are white (aa genotype) and 468 are black (AA or Aa genotype). Calculate the frequency of the white allele (a).

Accepted Answer

$$q = \sqrt{\frac{32}{500}} = 0.253$$

Question 11

Which of the following best describes stabilizing selection?

Accepted Answer

Selection favors individuals with intermediate trait values.

Question 12

Which evolutionary mechanism is most likely to decrease genetic variation in a small population?

Accepted Answer

Genetic drift

Question 13

A population of salmon in a river is being eaten by bears. Over time, only the fastest salmon survive and reproduce. Which pattern of natural selection is this?

Accepted Answer

Directional selection

Question 14

Which of the following is NOT an assumption of the Hardy-Weinberg principle?

Accepted Answer

Small population size

Question 15

In a population, the genotype frequencies are $$AA = 0.684$$, $$Aa = 0.286$$, and $$aa = 0.03. $$What is the frequency of the A allele?

Accepted Answer

$$p = 0.684 + 0.143 = 0.827$$

Question 16

Which evolutionary mechanism can both increase and decrease genetic variation depending on the direction of movement between populations?

Accepted Answer

Gene flow

Question 17

Which of the following scenarios best illustrates disruptive selection?

Accepted Answer

Mice with either very light or very dark fur survive better than those with intermediate fur color.

Question 18

Which of the following statements about adaptation is correct?

Accepted Answer

Adaptations are heritable traits that increase an organism's fitness in a particular environment.

Question 19

Which of the following is most likely to occur in a small population compared to a large population?

Accepted Answer

Genetic drift has a greater effect on allele frequencies.

Question 20

Which of the following is a direct consequence of more offspring being born than can survive, according to Darwin's postulates?

Accepted Answer

Competition for resources leads to differential survival.

Mechanisms of Evolution and Patterns of Natural Selection

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