Question 1

Which of the following best describes the difference between a gene and an allele?

Accepted Answer

A gene is a region of DNA coding for a protein, while an allele is an alternate form of that gene.

Question 2

In a population of rabbits, the coat color gene has two alleles: B (black, dominant) and b (brown, recessive). If a rabbit has the genotype Bb, what is its phenotype?

Accepted Answer

Black hair

Question 3

Which of the following Hardy-Weinberg assumptions would be violated if a population of rabbits experienced a sudden influx of new individuals from another population?

Accepted Answer

New alleles are not entering the population.

Question 4

A rabbit with genotype bbDd is crossed with a rabbit with genotype bbdd. What is the probability that their offspring will have the genotype bbdd?

Accepted Answer

$$0.5$$

Question 5

If the frequency of the d allele (dilute coat color) in a rabbit population is $$0.3$$, what is the expected frequency of homozygous dd individuals according to Hardy-Weinberg equilibrium?

Accepted Answer

$$0.09 ($$since $$q^2$$ = $$0.3^2 = 0.09$)

Question 6

Which evolutionary mechanism is most likely responsible for a drastic reduction in genetic variation after a natural disaster wipes out most of a population?

Accepted Answer

Bottleneck effect

Question 7

A population of ducks has two alleles at the color locus: C (functional tyrosinase) and c (nonfunctional tyrosinase). If the frequency of the cc genotype is $$0.16$$, what is the frequency of the c allele?

Accepted Answer

$$0.4 ($$since $$c^2 = 0.16$, so c = 0.4$)

Question 8

Which of the following scenarios best illustrates genetic drift?

Accepted Answer

A small group of rabbits is isolated on an island, and by chance, only brown allele carriers reproduce.

Question 9

In a population of rabbits, the allele frequencies for B (black) and b (brown) are $$p = 0.7$$ and $$q = 0.3$$, respectively. What is the expected frequency of heterozygous (Bb) individuals?

Accepted Answer

$$2pq = 2(0.7)(0.3) = 0.42$$

Question 10

Which of the following is an example of epistasis?

Accepted Answer

A gene for pigment production masks the effect of a gene for pigment color in ducks.

Question 11

A population of rabbits is in Hardy-Weinberg equilibrium. If the frequency of the B allele is $$0.6$$, what is the expected frequency of BB individuals?

Accepted Answer

$$0.36 ($$since $$p^2$$ = $$0.6^2 = 0.36$)

Question 12

Which agent of evolutionary change is most likely to increase the frequency of homozygous individuals in a population?

Accepted Answer

Nonrandom mating

Question 13

If a rabbit with genotype BbCc is crossed with a rabbit with genotype bbcc, what is the probability that their offspring will have genotype bbcc?

Accepted Answer

$$0.25$$

Question 14

Which of the following best explains why natural selection can change allele frequencies in a population?

Accepted Answer

Some alleles confer a survival advantage, leading to increased reproductive success for individuals carrying those alleles.

Question 15

A population of ducks has the following genotype frequencies at the color locus: $$CC = 0.16$$, $$Cc = 0.48$$, $$cc = 0.36. $$What is the frequency of the C allele?

Accepted Answer

$$C = 0.4 ($$since $$C = CC + 0.5 	imes Cc = 0.16 + 0.24 = 0.4)$$

Question 16

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

Accepted Answer

Natural selection is acting on the genetic locus.

Question 17

If a population of rabbits has a high frequency of the lethal allele due to inbreeding, which evolutionary agent is most likely responsible?

Accepted Answer

Nonrandom mating

Question 18

A population of rabbits has allele frequencies $$B = 0.7$$ and $$b = 0.3. $$What is the expected proportion of rabbits with brown hair (bb genotype)?

Accepted Answer

$$q^2$$ = $$(0.3)^2 = 0.09$

Question 19

In a duck population, the genotype MM at the M locus and ee at the E locus must both be present for the apricot phenotype. If the probability of MM is $$0.5$$ and ee is $$0.5$$, what is the probability of an offspring being apricot if dd at the D locus is also required and its probability is $$0.5$$?

Accepted Answer

$$0.125 ($$since $$0.5 	imes 0.5 	imes 0.5 = 0.125)$$

Genetic Variation and Population Genetics in Cell Biology

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