Q: A population has allele frequencies $$p = 0.7$$ for $$A$$ and $$q = 0.3$$ for $$a. $$According to Hardy–Weinberg equilibrium, what is the expected frequency of heterozygotes ($$Aa) in $$the next generation?

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

Q: In a population, the frequency of the recessive allele for cystic fibrosis ($$q) is$$ $$0.02. $$What is the expected frequency of carriers (heterozygotes) under Hardy–Weinberg equilibrium?

$$2pq = 2 \times 0.98 \times 0.02 = 0.0392$$

Q: A population of 100 individuals has the following CCR5 genotypes: 1/1 = 79, 1/Δ32 = 20, Δ32/Δ32 = 1. What is the frequency of the Δ32 allele?

$$f(\Delta 32) = \frac{2 \times 1 + 20}{2 \times 100} = \frac{2 + 20}{200} = 0.11$$

Q: A population is in Hardy–Weinberg equilibrium with three alleles: $$I^A = 0.38$$, $$I^B = 0.11$$, $$i = 0.51. $$What is the expected frequency of genotype $$I^A i$$?

$$2pr = 2 \times 0.38 \times 0.51 = 0.3876$$

Q: A population of 200 individuals has the following genotype counts for a gene: $$AA = 120$$, $$Aa = 60$$, $$aa = 20. $$What is the frequency of allele $$A$$?

$$f(A) = \frac{2 \times 120 + 60}{2 \times 200} = \frac{240 + 60}{400} = 0.75$$

Question 1

Which of the following is the ultimate source of new alleles in a population, and why?

Accepted Answer

Mutation, because it creates new DNA sequences for genes.

Question 2

A population has allele frequencies $$p = 0.7$$ for $$A$$ and $$q = 0.3$$ for $$a. $$According to Hardy–Weinberg equilibrium, what is the expected frequency of heterozygotes ($$Aa) in $$the next generation?

Accepted Answer

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

Question 3

Which of the following scenarios best illustrates the founder effect?

Accepted Answer

A small group of birds colonizes a new island, and their descendants have different allele frequencies than the original population.

Question 4

In a population, the frequency of the recessive allele for cystic fibrosis ($$q) is$$ $$0.02. $$What is the expected frequency of carriers (heterozygotes) under Hardy–Weinberg equilibrium?

Accepted Answer

$$2pq = 2 	imes 0.98 	imes 0.02 = 0.0392$$

Question 5

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

Accepted Answer

Finite population size

Question 6

A population of 100 individuals has the following CCR5 genotypes: 1/1 = 79, 1/Δ32 = 20, Δ32/Δ32 = 1. What is the frequency of the Δ32 allele?

Accepted Answer

$$f(\Delta 32) = \frac{2 	imes 1 + 20}{2 	imes 100} = \frac{2 + 20}{200} = 0.11$$

Question 7

Which genotype for the CCR5 gene confers resistance to most sexually transmitted strains of HIV-1?

Accepted Answer

Δ32/Δ32

Question 8

A population is in Hardy–Weinberg equilibrium with three alleles: $$I^A = 0.38$$, $$I^B = 0.11$$, $$i = 0.51. $$What is the expected frequency of genotype $$I^A i$$?

Accepted Answer

$$2pr = 2 	imes 0.38 	imes 0.51 = 0.3876$$

Question 9

Which process is responsible for random changes in allele frequencies, especially in small populations?

Accepted Answer

Genetic drift

Question 10

A population has genotype frequencies for a gene as follows: $$AA = 0.49$$, $$Aa = 0.42$$, $$aa = 0.09. $$Are these frequencies consistent with Hardy–Weinberg equilibrium?

Accepted Answer

Yes, because $$p^2 + 2pq$$ + $$q^2 = 1$

Question 11

Which of the following best describes gene flow?

Accepted Answer

Movement of alleles between populations due to migration

Question 12

If a population is not in Hardy–Weinberg equilibrium, which of the following could be a possible explanation?

Accepted Answer

There is non-random mating

Question 13

Which of the following is a key requirement for speciation to occur?

Accepted Answer

Reproductive isolation

Question 14

A population of 200 individuals has the following genotype counts for a gene: $$AA = 120$$, $$Aa = 60$$, $$aa = 20. $$What is the frequency of allele $$A$$?

Accepted Answer

$$f(A) = \frac{2 	imes 120 + 60}{2 	imes 200} = \frac{240 + 60}{400} = 0.75$$

Question 15

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

Accepted Answer

Microevolution refers to changes within populations, while macroevolution involves the emergence of new species.

Question 16

Which of the following is a consequence of the genetic bottleneck effect?

Accepted Answer

Reduced genetic diversity due to a drastic reduction in population size

Question 17

A population has genotype frequencies for sickle-cell hemoglobin: $$SS = 0.756$$, $$Ss = 0.242$$, $$ss = 0.002. $$What is the frequency of the $$s$$ allele?

Accepted Answer

$$f(s) = \frac{2 	imes 0.002 + 0.242}{2} = 0.123$$

Question 18

Which of the following best describes a phylogenetic tree?

Accepted Answer

A diagram showing the evolutionary relationships among species based on genetic differences

Question 19

Which of the following is true about the Hardy–Weinberg law?

Accepted Answer

It assumes no mutation, migration, selection, or genetic drift.

Population and Evolutionary Genetics: Mechanisms, Hardy–Weinberg Law, and Applications

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