Q: A population of 200 butterflies has two alleles for wing color: B (blue) and b (brown). There are 98 BB, 84 Bb, and 18 bb individuals. What is the frequency of the b allele in this population?

$$\frac{(2 \times 18) + 84}{2 \times 200} = \frac{36 + 84}{400} = \frac{120}{400} = 0.3$$

Q: In a population at Hardy-Weinberg equilibrium, the frequency of allele A is $$p = 0.7$$ and allele a is $$q = 0.3. $$What is the expected frequency of heterozygotes (Aa)?

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

Q: A population of 100 frogs has the following genotype frequencies: 64 GG, 32 Gg, and 4 gg. If inbreeding occurs with an inbreeding coefficient $$f = 0.25$$, what will be the new frequency of heterozygotes (Gg)?

$$2pq(1-f) = 2 \times 0.8 \times 0.2 \times (1-0.25) = 0.32 \times 0.75 = 0.24$$

Q: A population of 1000 individuals has a mutation rate $$\mu = 2 \times 10$$^{-5}$$ per gene per generation. What is the expected number of new mutations for this gene in one generation?

$$2N\mu = 2 \times 1000 \times 2 \times 10$$^{-5}$$ = 0.04$$

Question 1

A population of 200 butterflies has two alleles for wing color: B (blue) and b (brown). There are 98 BB, 84 Bb, and 18 bb individuals. What is the frequency of the b allele in this population?

Accepted Answer

$$\frac{(2 	imes 18) + 84}{2 	imes 200} = \frac{36 + 84}{400} = \frac{120}{400} = 0.3$$

Question 2

Which of the following scenarios best illustrates the founder effect?

Accepted Answer

A small group of lizards is swept by a storm to a new island, where they establish a population with different allele frequencies than the mainland.

Question 3

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

Accepted Answer

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

Question 4

A population of 100 frogs has the following genotype frequencies: 64 GG, 32 Gg, and 4 gg. If inbreeding occurs with an inbreeding coefficient $$f = 0.25$$, what will be the new frequency of heterozygotes (Gg)?

Accepted Answer

$$2pq(1-f) = 2 	imes 0.8 	imes 0.2 	imes (1-0.25) = 0.32 	imes 0.75 = 0.24$$

Question 5

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

Accepted Answer

Strong natural selection

Question 6

A new mutation arises in a population of $$N = 50$$ individuals. What is the probability that this mutation will eventually become fixed in the population due to genetic drift?

Accepted Answer

$$\frac{1}{2N} = \frac{1}{100} = 0.01$$

Question 7

In a population, the fitness values for genotypes are $$w_{AA} = 0.7$$, $$w_{Aa} = 1.0$$, and $$w_{aa} = 0.4. $$What is the equilibrium frequency of allele A under heterozygote advantage?

Accepted Answer

$$\hat{p} = \frac{s_{aa}}{s_{AA} + s_{aa}} = \frac{0.6}{0.3 + 0.6} = 0.67$$

Question 8

Which of the following best describes negative frequency-dependent selection?

Accepted Answer

Rare genotypes have higher fitness, so their frequency increases until they are no longer rare.

Question 9

A population of birds lays an average of 6 eggs per nest. Nests with fewer than 4 or more than 8 eggs have lower survival rates. What type of natural selection is most likely acting on clutch size?

Accepted Answer

Stabilizing selection

Question 10

A population of 1000 individuals has a mutation rate $$\mu = 2 	imes 10$$^{-5}$$ per gene per generation. What is the expected number of new mutations for this gene in one generation?

Accepted Answer

$$2N\mu = 2 	imes 1000 	imes 2 	imes 10$$^{-5}$$ = 0.04$$

Question 11

In a migration scenario, the frequency of allele A is 0.8 in the donor population and 0.4 in the recipient population. If 10 migrants join a recipient population of 90, what is the new frequency of allele A in the conglomerate population?

Accepted Answer

Proportion of migrants $$m = \frac{10}{100} = 0.1$$; $$\Delta p_c = 0.1 	imes (0.8 - 0.4) = 0.04$$; new frequency $$= 0.4 + 0.04 = 0.44$$

Question 12

Which of the following is a real-world example of balancing selection due to heterozygote advantage?

Accepted Answer

The high frequency of the HbS allele in regions where malaria is endemic

Question 13

Which mechanism is most likely to increase the proportion of homozygotes in a population without changing allele frequencies?

Accepted Answer

Inbreeding

Question 14

Which of the following statements about genetic drift is correct?

Accepted Answer

Genetic drift has a stronger effect in small populations, increasing the chance of allele fixation or loss.

Question 15

Which process is responsible for the creation of new genes with novel combinations of functional domains by rearranging exons?

Accepted Answer

Exon shuffling

Question 16

A population of snails lives in both woods and open fields. Brown shells are favored in woods, yellow shells in fields, and pink shells in leaf litter. What type of selection is most likely maintaining this shell color diversity?

Accepted Answer

Disruptive selection

Question 17

Which of the following is NOT a source of new genetic variation listed in the study materials?

Accepted Answer

Genetic drift

Question 18

A population is in Hardy-Weinberg equilibrium for a gene with two alleles, M and m. If the frequency of genotype Mm is 0.48 and the frequency of allele M is 0.6, what is the expected frequency of genotype mm?

Accepted Answer

$$q = 1 - 0.6 = 0.4;\ q^2$ = 0.16$$

Question 19

Which of the following best describes the effect of bidirectional migration between two populations?

Accepted Answer

It reduces allele frequency differences between populations and increases genetic diversity within populations.

Question 20

Which of the following is a plausible consequence of inbreeding in a natural population?

Accepted Answer

Increased frequency of recessive genetic diseases due to higher homozygosity

Population Genetics: Principles, Models, and Applications

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