Q: A population of 10 individuals has 3 genotype AA, 5 genotype Aa, and 2 genotype aa. What is the frequency of the A allele ($$p$$)?

$$p = \frac{3 \times 2 + 5}{20} = 0.55$$

Q: 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 ($$Aa$$)?

$$2pq = 2 \times 0.7 \times 0.3 = 0.42$$

Question 1

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

Accepted Answer

Natural selection favors certain alleles.

Question 2

A population of 10 individuals has 3 genotype AA, 5 genotype Aa, and 2 genotype aa. What is the frequency of the A allele ($$p$$)?

Accepted Answer

$$p = \frac{3 	imes 2 + 5}{20} = 0.55$$

Question 3

Which type of natural selection increases the frequency of individuals with extreme phenotypes and can lead to speciation?

Accepted Answer

Disruptive selection

Question 4

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

$$2pq = 2 	imes 0.7 	imes 0.3 = 0.42$$

Question 5

Which evolutionary process is most likely responsible for a sudden reduction in genetic diversity due to a natural disaster?

Accepted Answer

Genetic bottleneck

Question 6

A population of birds migrates to a new island and establishes a new population. The allele frequencies in the new population differ from the original. This is an example of:

Accepted Answer

Founder effect

Question 7

Which of the following scenarios best illustrates balancing selection?

Accepted Answer

A population where heterozygotes have higher fitness than either homozygote.

Question 8

If the frequency of genotype $$AA is$$ $$0.36$$, $$Aa is$$ $$0.48$$, and $$aa is$$ $$0.16$$, what are the allele frequencies for $$A$$ and $$a$$?

Accepted Answer

$$f(A) = 0.6$$, $$f(a) = 0.4$$

Question 9

Which process introduces new alleles into a population by the movement of individuals between populations?

Accepted Answer

Gene flow

Question 10

A population of plants is exposed to a new pesticide. Over time, only those with a rare allele survive and reproduce. Which type of selection is occurring?

Accepted Answer

Directional selection

Question 11

Which of the following is a consequence of nonrandom mating?

Accepted Answer

Increased frequency of homozygotes

Question 12

Which equation represents the Hardy-Weinberg equilibrium for genotype frequencies?

Accepted Answer

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

Question 13

Which evolutionary process is most likely to decrease genetic variation in a small population over time due to random chance?

Accepted Answer

Genetic drift

Question 14

A population of fish shows a decrease in the frequency of both extreme phenotypes, with an increase in intermediate phenotypes. What type of selection is this?

Accepted Answer

Stabilizing selection

Question 15

Which of the following is true about mutation as an evolutionary process?

Accepted Answer

It is the ultimate source of new alleles.

Question 16

Sexual selection often leads to sexual dimorphism. Which of the following is an example of sexual dimorphism?

Accepted Answer

Male lions have manes while females do not.

Question 17

Which scenario best illustrates the effect of gene flow on a population?

Accepted Answer

A population receives new alleles from migrating individuals, increasing genetic diversity.

Question 18

In a population, the frequency of allele $$A is$$ $$0.4$$ and allele $$a is$$ $$0.6. $$What is the expected frequency of genotype $$aa$$ under Hardy-Weinberg equilibrium?

Accepted Answer

$$q^2$$ = $$0.6^2 = 0.36$

Question 19

Which of the following is most likely to result in the formation of new species?

Accepted Answer

Disruptive selection

Question 20

A population of humans experiences a genetic bottleneck. Which of the following is a likely consequence?

Accepted Answer

Reduced genetic diversity and increased frequency of certain alleles.

Evolutionary Processes: Mechanisms of Evolution (Ch. 23) – Study Notes

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