Q: A population of beetles has two alleles for shell color: G (green) and g (brown). If the frequency of G is $$p = 0.7$$ and the frequency of g is $$q = 0.3$$, what is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium?

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

Q: In a population, the frequency of a recessive allele causing a genetic disorder is $$q = 0.05. $$Assuming Hardy-Weinberg equilibrium, what percentage of the population are carriers (heterozygotes) for this allele?

$$2pq = 2 \times 0.95 \times 0.05 = 0.095 or 9.5$$%

Question 1

Which of the following best describes the primary difference between microevolution and macroevolution?

Accepted Answer

Microevolution refers to changes in allele frequencies within a population over generations, while macroevolution involves the formation of new species or higher taxonomic groups.

Question 2

A population of beetles has two alleles for shell color: G (green) and g (brown). If the frequency of G is $$p = 0.7$$ and the frequency of g is $$q = 0.3$$, what is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium?

Accepted Answer

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

Question 3

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

Accepted Answer

A small group of birds is blown to a new island by a storm, and their descendants have different allele frequencies than the original population.

Question 4

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

Accepted Answer

Natural selection

Question 5

In a population, the frequency of a recessive allele causing a genetic disorder is $$q = 0.05. $$Assuming Hardy-Weinberg equilibrium, what percentage of the population are carriers (heterozygotes) for this allele?

Accepted Answer

$$2pq = 2 	imes 0.95 	imes 0.05 = 0.095 or 9.5$$%

Question 6

Which of the following best explains why nucleotide variability rarely results in phenotypic variation?

Accepted Answer

Most nucleotide differences occur in non-coding DNA segments (introns), which do not affect phenotype.

Question 7

A population of wild fruit flies is exposed to DDT, and over time, the frequency of an allele for DDT resistance increases. Which evolutionary mechanism is primarily responsible for this change?

Accepted Answer

Natural selection

Question 8

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

Accepted Answer

Small population size

Question 9

In a population of scale-eating fish, the fitness of a phenotype depends on how common it is. This is an example of:

Accepted Answer

Frequency-dependent selection

Question 10

Which of the following best illustrates heterozygote advantage?

Accepted Answer

Individuals heterozygous for the sickle cell allele are more resistant to malaria than either homozygote.

Question 11

Which process is most likely to reduce genetic variation within a population?

Accepted Answer

Genetic drift

Question 12

A population of plants is exposed to a sudden drought, drastically reducing its size. The surviving plants have a different allele frequency than the original population. This is an example of:

Accepted Answer

The bottleneck effect

Question 13

Which of the following is an example of disruptive selection?

Accepted Answer

A population of birds where both small and large beak sizes are favored over intermediate sizes due to the availability of two distinct food sources.

Question 14

Which of the following statements about gene flow is correct?

Accepted Answer

Gene flow tends to reduce genetic differences between populations over time.

Question 15

Which of the following is a real-world example of sexual selection leading to sexual dimorphism?

Accepted Answer

Male peacocks have elaborate tail feathers, while females do not.

Question 16

Which of the following is a source of new alleles in a population?

Accepted Answer

Mutation

Question 17

A population of mice has a gene with two alleles, A and a. If the frequency of AA is $$0.36$$, Aa is $$0.48$$, and aa is $$0.16$$, is this population in Hardy-Weinberg equilibrium?

Accepted Answer

Yes, because $$p^2 = 0.36$, 2pq = 0.48$, and q^2$ = 0.16$$; $$p + q = 1.$$

Question 18

Which of the following best describes the role of sexual reproduction in genetic variation?

Accepted Answer

It recombines existing alleles through crossing over, independent assortment, and fertilization.

Question 19

Which of the following statements about natural selection is FALSE?

Accepted Answer

Natural selection acts directly on genotypes, not phenotypes.

Question 20

In a population, a neutral mutation occurs in a non-coding region of DNA. What is the most likely evolutionary consequence of this mutation?

Accepted Answer

It will have no effect on the phenotype and may persist in the population without selective advantage or disadvantage.

Mechanisms of Evolution and Genetic Variation in Populations

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