Q: In a population of 100 lizards, 60 are green (genotype S+S+), 30 are blue-green (genotype S+S*), and 10 are blue (genotype S*S*). What is the frequency of the S* allele?

$$q = \frac{30 + 2 \times 10}{200} = \frac{30 + 20}{200} = \frac{50}{200} = 0.25$$

Q: A population of 200 people has two alleles for hair type: A (curly) and a (straight). 80 people have curly hair (AA), 60 have wavy hair (Aa), and 60 have straight hair (aa). What is the frequency of the A allele?

$$p = \frac{2 \times 80 + 60}{2 \times 200} = \frac{160 + 60}{400} = \frac{220}{400} = 0.55$$

Q: If $$p = 0.7$$ and $$q = 0.3 in a $$population at Hardy-Weinberg equilibrium, what is the expected frequency of heterozygotes?

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

Q: A population of 1000 individuals has a dominant allele frequency $$p = 0.8$$ and a recessive allele frequency $$q = 0.2. $$How many individuals are expected to be homozygous recessive under Hardy-Weinberg equilibrium?

$$q^2$$ = $$0.2^2 = 0.04$; 0.04$$ \times 1000 = 40$$

Question 1

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

Accepted Answer

Non-random mating

Question 2

In a population of 100 lizards, 60 are green (genotype S+S+), 30 are blue-green (genotype S+S*), and 10 are blue (genotype S*S*). What is the frequency of the S* allele?

Accepted Answer

$$q = \frac{30 + 2 	imes 10}{200} = \frac{30 + 20}{200} = \frac{50}{200} = 0.25$$

Question 3

Which evolutionary mechanism is most likely to cause large, unpredictable changes in allele frequencies in small populations?

Accepted Answer

Genetic drift

Question 4

A population of 200 people has two alleles for hair type: A (curly) and a (straight). 80 people have curly hair (AA), 60 have wavy hair (Aa), and 60 have straight hair (aa). What is the frequency of the A allele?

Accepted Answer

$$p = \frac{2 	imes 80 + 60}{2 	imes 200} = \frac{160 + 60}{400} = \frac{220}{400} = 0.55$$

Question 5

Which scenario best illustrates the founder effect?

Accepted Answer

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

Question 6

If $$p = 0.7$$ and $$q = 0.3 in a $$population at Hardy-Weinberg equilibrium, what is the expected frequency of heterozygotes?

Accepted Answer

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

Question 7

Which of the following is an example of frequency-dependent selection?

Accepted Answer

A rare phenotype has a survival advantage because predators focus on the common phenotype.

Question 8

Why does genetic drift tend to reduce genetic variation in small populations?

Accepted Answer

Random fluctuations can lead to the loss of alleles over generations.

Question 9

Which of the following statements about mutation is TRUE in the context of population genetics?

Accepted Answer

Mutations are the primary source of genetic variation but occur rarely.

Question 10

A population of 500 plants undergoes a bottleneck event, reducing its size to 20. What is the most likely genetic consequence?

Accepted Answer

Loss of genetic variation due to genetic drift

Question 11

Which equation correctly represents the Hardy-Weinberg principle for genotype frequencies?

Accepted Answer

$$p^2 + 2pq$$ + $$q^2 = 1$

Question 12

In a population at Hardy-Weinberg equilibrium, if the frequency of the recessive phenotype is 0.09, what is the frequency of the recessive allele?

Accepted Answer

$$q = \sqrt{0.09} = 0.3$$

Question 13

Which of the following is NOT a reason why evolution does not produce perfect adaptations?

Accepted Answer

Mutations always produce beneficial traits

Question 14

Which process introduces new alleles into a population from another population?

Accepted Answer

Gene flow

Question 15

A population of 1000 individuals has a dominant allele frequency $$p = 0.8$$ and a recessive allele frequency $$q = 0.2. $$How many individuals are expected to be homozygous recessive under Hardy-Weinberg equilibrium?

Accepted Answer

$$q^2$$ = $$0.2^2 = 0.04$; 0.04$$ 	imes 1000 = 40$$

Question 16

Which type of selection favors individuals with intermediate traits over those with extreme traits?

Accepted Answer

Stabilizing selection

Question 17

If a population is not in Hardy-Weinberg equilibrium, what can be inferred?

Accepted Answer

One or more evolutionary forces are acting on the population

Question 18

Which of the following best describes heterozygote advantage?

Accepted Answer

Heterozygotes have higher fitness than either homozygote

Question 19

A population of 500 water snakes has 335 green (GG), 130 blue-green (Gg), and 35 blue (gg) individuals. What is the frequency of the g allele?

Accepted Answer

$$q = \frac{2 	imes 35 + 130}{2 	imes 500} = \frac{70 + 130}{1000} = \frac{200}{1000} = 0.20$$

Question 20

Which of the following is a real-world example of gene flow affecting local adaptation?

Accepted Answer

Migration of water snakes between islands and mainland changes allele frequencies

Population Genetics and Hardy-Weinberg Equilibrium: Study Notes

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