Question 1

Which of the following evolutionary forces is most likely to increase genetic variation within a population by introducing new alleles?

Accepted Answer

Mutation

Question 2

According to the Hardy-Weinberg Equilibrium, if $p$ is the frequency of the dominant allele and $q$ is the frequency of the recessive allele, which equation must always be true in a population not evolving?

Accepted Answer

$p + q = 1$

Question 3

A population of fish in Lake Tanganyika exhibits frequency-dependent selection due to jaw asymmetry. What is the expected outcome for the frequency of 'left-mouthed' and 'right-mouthed' fish over time?

Accepted Answer

Both jaw types will be maintained at intermediate frequencies

Question 4

Which scenario best describes balancing selection?

Accepted Answer

Selection favoring individuals with intermediate trait values

Question 5

In a population, the frequency of allele $A$ is $0.7$ and allele $a$ is $0.3$. What is the expected frequency of heterozygotes ($A a$) under Hardy-Weinberg equilibrium?

Accepted Answer

$0.42$

Question 6

Why do deleterious alleles often persist in a population for many generations, even when selection acts against them?

Accepted Answer

Because most copies are hidden in heterozygotes

Question 7

Which of the following best describes the difference between a deterministic and a stochastic model in population genetics?

Accepted Answer

Deterministic models make exact predictions; stochastic models incorporate chance events

Question 8

A population of 1000 individuals has a mutation rate of $1 	imes 10^{-6}$ per generation for a recessive deleterious allele. If the selection coefficient against the allele is $0.1$, what is the main reason this allele is maintained at a low frequency?

Accepted Answer

Mutation introduces the allele while selection removes it

Question 9

Which of the following is true about genetic drift in small populations?

Accepted Answer

It causes allele frequencies to fluctuate widely from generation to generation

Question 10

In Peter Buri's experiment with fruit flies, what was the main outcome observed in the replicate populations over time?

Accepted Answer

Populations drifted toward fixation or loss of the allele, and heterozygosity decreased

Question 11

Which of the following best explains why mutation is considered a 'weak' evolutionary force?

Accepted Answer

Mutation rates are extremely low, so it takes many generations to significantly change allele frequencies

Question 12

Which of the following is an example of positive selection?

Accepted Answer

Selection favoring a beneficial allele

Question 13

If the $dN/dS$ ratio for a gene is greater than $1$, what does this indicate?

Accepted Answer

Positive selection

Question 14

Which of the following is most likely to cause genetic divergence BETWEEN isolated populations?

Accepted Answer

Genetic drift

Question 15

A population is at equilibrium for a deleterious allele. What two variables determine the equilibrium frequency ($q_e$) of this allele?

Accepted Answer

Mutation rate and selection coefficient

Question 16

Which of the following best describes the founder effect?

Accepted Answer

A small number of individuals establish a new population, causing sampling error

Question 17

Why is mutation necessary for adaptive selection?

Accepted Answer

Mutation provides the raw material (new alleles) for evolution

Question 18

Which of the following is true about equilibrium in population genetics?

Accepted Answer

It is the point at which there is no change in allelic frequency due to mutation

Question 19

Which of the following is a common source of spontaneous mutation?

Accepted Answer

Replication error

Question 20

In the context of population genetics, what is relative fitness?

Accepted Answer

The ability of different genotypes to pass on their alleles to future generations compared to others

Population Genetics: Forces Shaping Genetic Variation

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