Q: If the frequency of allele $$A in a $$population is $$p = 0.7$$ and the frequency of allele $$a is$$ $$q = 0.3$$, what is the expected frequency of heterozygotes ($$Aa) $$under Hardy–Weinberg equilibrium? Use the formula $$2pq.$$

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

Question 1

Which of the following best defines evolution in a biological context?

Accepted Answer

A change in allele frequencies within a population over time.

Question 2

A population of beetles is isolated on an island. Over time, a hurricane drastically reduces their numbers, leaving only a few survivors. Which evolutionary mechanism is most directly illustrated by this scenario?

Accepted Answer

Bottleneck effect

Question 3

Which of the following is NOT a condition required for Hardy–Weinberg equilibrium?

Accepted Answer

Small population size

Question 4

If the frequency of allele $$A in a $$population is $$p = 0.7$$ and the frequency of allele $$a is$$ $$q = 0.3$$, what is the expected frequency of heterozygotes ($$Aa) $$under Hardy–Weinberg equilibrium? Use the formula $$2pq.$$

Accepted Answer

$$2 	imes 0.7 	imes 0.3 = 0.42$$

Question 5

Which statement about natural selection is correct?

Accepted Answer

Natural selection filters existing phenotypic variation.

Question 6

A population of birds exhibits a wide range of beak sizes. If birds with intermediate beak sizes are less successful at obtaining food than those with either very large or very small beaks, which type of selection is occurring?

Accepted Answer

Disruptive selection

Question 7

Which of the following best describes gene flow?

Accepted Answer

The movement of alleles between populations through migration.

Question 8

A scientist observes that a certain population of bacteria becomes resistant to an antibiotic after several generations of exposure. Which statement best explains this observation?

Accepted Answer

Bacteria with pre-existing resistance survived and reproduced, increasing the frequency of resistance alleles.

Question 9

Which of the following is an example of the founder effect?

Accepted Answer

A few individuals leave a population and establish a new colony with a different allele frequency.

Question 10

In the context of sexual selection, which scenario best illustrates a trade-off in fitness?

Accepted Answer

A bird with dull feathers survives longer but attracts fewer mates.

Question 11

Which of the following is a misconception about evolution, based on the study of antibiotic resistance?

Accepted Answer

Natural selection causes genetic changes in individuals to help them survive.

Question 12

A population of mammals has a bell-shaped curve for body size. If environmental pressures favor individuals with average body size, what type of selection is most likely occurring?

Accepted Answer

Stabilizing selection

Question 13

Which of the following best describes the relationship between genotype and phenotype in the context of natural selection?

Accepted Answer

The genotype interacts with the environment to produce the phenotype, which is subject to selection.

Question 14

If a population is in Hardy–Weinberg equilibrium, which of the following statements must be true?

Accepted Answer

No gene flow is occurring between populations.

Question 15

Which of the following is the ultimate source of all genetic variability in a population?

Accepted Answer

Mutation

Question 16

A population of insects is exposed to a new pesticide. After several generations, most individuals are resistant. Which pattern of selection does this illustrate?

Accepted Answer

Directional selection

Question 17

Which of the following scenarios best illustrates coevolution?

Accepted Answer

A predator evolves sharper teeth while its prey evolves tougher skin.

Question 18

If a population of 1000 individuals has 360 individuals with genotype $$aa$$, what is the frequency of allele $$a$$? Use the Hardy–Weinberg formula $$q^2$$ = 	ext{frequency of } aa$$.

Accepted Answer

$$q = \sqrt{0.36} = 0.6$$

Question 19

Why does low genetic diversity increase the risk of extinction in a population that has undergone a bottleneck?

Accepted Answer

It reduces the population's ability to adapt to new environmental challenges.

Question 20

Which of the following best explains why the influenza virus requires a new vaccine each year?

Accepted Answer

The virus undergoes rapid mutation, changing its gene pool annually.

How Populations Evolve: Mechanisms and Patterns of Evolutionary Change

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