Q: In a population of 1000 individuals, 490 are $$AA$$, 420 are $$Aa$$, and 90 are $$aa. $$What is the frequency of the $$a$$ allele?

$$q = \frac{(2 \times 90) + 420}{2 \times 1000} = 0.3$$

Question 1

Which of the following best explains why the average beak depth of Galapagos finches increased after the 1977 drought?

Accepted Answer

Finches with larger beaks survived and reproduced more successfully, increasing the proportion of large-beaked offspring.

Question 2

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

Accepted Answer

Natural selection

Question 3

A population of 500 wildflowers has the following genotype counts: 320 $$CRCR$$, 160 $$CRCW$$, and 20 $$CWCW. $$What is the frequency of the $$CR$$ allele?

Accepted Answer

$$0.8$$

Question 4

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

Accepted Answer

Small population size

Question 5

If $$q^2 = 0.0001$ for a recessive genetic disorder in a population, what is the frequency of the recessive allele (q$)?

Accepted Answer

$$q = 0.01$$

Question 6

Which of the following best describes genetic drift?

Accepted Answer

A process where chance events cause unpredictable fluctuations in allele frequencies, especially in small populations.

Question 7

A population is in Hardy-Weinberg equilibrium with $$p = 0.7$$ and $$q = 0.3. $$What is the expected frequency of heterozygotes?

Accepted Answer

$$2pq = 2(0.7)(0.3) = 0.42$$

Question 8

Which scenario is an example of the founder effect?

Accepted Answer

A few individuals colonize a new island, and their allele frequencies differ from the original population.

Question 9

Which of the following statements about mutations is correct?

Accepted Answer

Most mutations that alter phenotype are harmful, but some can be neutral or beneficial.

Question 10

In a population of 1000 individuals, 490 are $$AA$$, 420 are $$Aa$$, and 90 are $$aa. $$What is the frequency of the $$a$$ allele?

Accepted Answer

$$q = \frac{(2 	imes 90) + 420}{2 	imes 1000} = 0.3$$

Question 11

Which of the following is an example of gene flow?

Accepted Answer

A group of birds migrates to a new area and breeds with the local population, introducing new alleles.

Question 12

Which type of selection increases the frequency of individuals at both extremes of a phenotypic range?

Accepted Answer

Disruptive selection

Question 13

Why is genetic variation essential for evolution?

Accepted Answer

It provides the raw material for natural selection to act upon.

Question 14

Which of the following best describes a population in Hardy-Weinberg equilibrium?

Accepted Answer

Allele and genotype frequencies remain constant from generation to generation.

Question 15

A population of 100 individuals has 36 $$AA$$, 48 $$Aa$$, and 16 $$aa. Is $$this population in Hardy-Weinberg equilibrium?

Accepted Answer

Yes, because the observed genotype frequencies match the expected frequencies calculated using $$p^2$$, $$2pq$$, and $$q^2.$$

Question 16

Which of the following is an example of stabilizing selection?

Accepted Answer

Human birth weights are most commonly between 6.6 and 8.8 lbs, with very low or high weights being less common.

Question 17

Which of the following is a consequence of genetic drift?

Accepted Answer

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

Question 18

If a population has allele frequencies $$p = 0.6$$ and $$q = 0.4$$, what are the expected genotype frequencies under Hardy-Weinberg equilibrium?

Accepted Answer

$$p^2 = 0.36$, 2pq = 0.48$, q^2$ = 0.16$$

Question 19

Which of the following is an example of neutral variation?

Accepted Answer

A mutation in a noncoding region of DNA that does not affect phenotype.

Evolution of Populations: Mechanisms, Genetic Variation, and Hardy-Weinberg Equilibrium

Study Guide - Practice Questions

Study Guide - Flashcards