Q: A population of butterflies has two alleles for a gene: A and a. If the frequency of allele A is $p = 0.7$ and the frequency of allele a 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: A population of 200 individuals has the following genotype counts: 80 AA, 100 Aa, and 20 aa. What is the frequency of allele A?

$\frac{2 \times 80 + 100}{2 \times 200} = \frac{160 + 100}{400} = \frac{260}{400} = 0.65$

Question 1

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

Accepted Answer

There is a high rate of mutation introducing new alleles each generation.

Question 2

A population of butterflies has two alleles for a gene: A and a. If the frequency of allele A is $p = 0.7$ and the frequency of allele a 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 evolutionary process is best described as a change in allele frequencies due to the random sampling of alleles from one generation to the next?

Accepted Answer

Genetic drift

Question 4

A researcher finds that a population of lizards has a statistically significant difference in allele frequencies before and after a drought, with a $p$-value of $0.01$. What does this $p$-value indicate?

Accepted Answer

There is a 1% chance that the observed difference is due to random chance.

Question 5

Which mode of natural selection increases the frequency of individuals with extreme phenotypes at both ends of the distribution, often resulting in two distinct forms?

Accepted Answer

Disruptive selection

Question 6

If a population of 1000 individuals has 400 alleles of type A and 600 alleles of type a, what is the frequency of allele A?

Accepted Answer

$\frac{400}{1000} = 0.4$

Question 7

Which of the following scenarios best illustrates gene flow?

Accepted Answer

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

Question 8

A population of fish is exposed to a pollutant that kills only individuals with a certain genotype. Over time, the average genotype in the population shifts away from the susceptible genotype. Which mode of natural selection is this an example of?

Accepted Answer

Directional selection

Question 9

In a population, the frequency of allele A is $0.5$ and the frequency of allele a is $0.5$. If random mating occurs, what is the expected frequency of genotype AA in the next generation?

Accepted Answer

$p^2 = (0.5)^2 = 0.25$

Question 10

Which of the following best describes the bottleneck effect?

Accepted Answer

A sudden reduction in population size due to a natural disaster, leading to a loss of genetic diversity.

Question 11

A population of deer is split by a new highway, preventing individuals from crossing. Over time, the two populations develop different allele frequencies. Which evolutionary process is most likely responsible for the initial divergence?

Accepted Answer

Genetic isolation followed by drift and selection

Question 12

If a statistical test yields a $p$-value of $0.199$ when comparing observed and expected genotype frequencies, what is the correct interpretation?

Accepted Answer

The difference is not statistically significant; fail to reject the null hypothesis.

Question 13

Which of the following is an example of stabilizing selection?

Accepted Answer

Human birth weight, where both very small and very large babies have lower survival rates.

Question 14

A population of 200 individuals has the following genotype counts: 80 AA, 100 Aa, and 20 aa. What is the frequency of allele A?

Accepted Answer

$\frac{2 	imes 80 + 100}{2 	imes 200} = \frac{160 + 100}{400} = \frac{260}{400} = 0.65$

Question 15

Which process can increase genetic variation in a population by introducing new alleles?

Accepted Answer

Mutation

Question 16

In a population, the observed genotype frequencies are: AA = 0.36, Aa = 0.48, aa = 0.16. Are these frequencies consistent with Hardy-Weinberg equilibrium?

Accepted Answer

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

Question 17

Which of the following best distinguishes gene flow from genetic drift?

Accepted Answer

Gene flow involves movement of alleles between populations; genetic drift is random change within a population.

Question 18

A population of salamanders is split into two by a new road. Over time, one population is exposed to a new predator, while the other is not. Which evolutionary process is most likely to cause the two populations to become more different?

Accepted Answer

Natural selection

Question 19

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

Accepted Answer

A small group of individuals colonizes a new island, and their allele frequencies differ from the original population.

Question 20

If a population is in Hardy-Weinberg equilibrium, what will happen to allele frequencies over time in the absence of evolutionary forces?

Accepted Answer

They will remain constant from generation to generation.

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