Q: In a population of 100 individuals, 36 are homozygous dominant (BB), 48 are heterozygous (Bb), and 16 are homozygous recessive (bb). What is the frequency of the dominant allele $$B$$?

$$(2 \times 36 + 48) / (2 \times 100) = 0.60$$

Question 1

Which of the following mechanisms of evolution is defined as the random fluctuation of allele frequencies in a population, and is especially impactful in small populations?

Accepted Answer

Genetic drift

Question 2

A population of 20 individuals experiences a genetic bottleneck, reducing its size to 5. What is the most likely genetic consequence for this population?

Accepted Answer

Fixation of alleles and loss of genetic variation

Question 3

Which equation correctly represents the Hardy-Weinberg equilibrium for a gene with two alleles, $$A$$ and $$a$$, with frequencies $$p$$ and $$q$$?

Accepted Answer

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

Question 4

In a population of beetles, gene flow occurs when individuals from a population with allele frequency $$p = 0.8$$ migrate into a population with $$p = 0.2. $$What is the expected effect of gene flow on the allele frequencies of these populations?

Accepted Answer

Allele frequencies in both populations will become more similar

Question 5

Which of the following is the ultimate source of new alleles in a gene pool?

Accepted Answer

Mutation

Question 6

A population of flowering plants has three alleles for petal color: $$B_1$$, $$B_2$$, and $$B_3. If $$the frequency of $$B_1 is 0.43$$, $$B_2 is 0.37$$, and $$B_3 is 0.22$$, what is the total allele frequency in the population?

Accepted Answer

$$0.43 + 0.37 + 0.22 = 1.00$$

Question 7

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

Accepted Answer

Natural selection is acting on the trait

Question 8

In a population of 100 individuals, 36 are homozygous dominant (BB), 48 are heterozygous (Bb), and 16 are homozygous recessive (bb). What is the frequency of the dominant allele $$B$$?

Accepted Answer

$$(2 	imes 36 + 48) / (2 	imes 100) = 0.60$$

Question 9

Which scenario best illustrates the founder effect?

Accepted Answer

A small group of individuals establishes a new population in a different location, carrying only a subset of the original genetic variation

Question 10

Which type of non-random mating increases homozygosity in a population?

Accepted Answer

Assortative mating

Question 11

A population of plants is exposed to an herbivore that prefers blue flowers (80% eaten), blue-tipped flowers (70% eaten), and pink/white flowers (25% eaten). Over several generations, what is the most likely outcome for the frequency of the blue flower allele?

Accepted Answer

The frequency of the blue flower allele will decrease

Question 12

Which of the following statements about mutation is TRUE?

Accepted Answer

Mutations are random with respect to fitness and can be neutral, beneficial, or deleterious

Question 13

Which evolutionary mechanism can introduce new alleles into a population but cannot create new alleles?

Accepted Answer

Gene flow

Question 14

Inbreeding increases the probability that an individual will be homozygous for a harmful recessive allele. What is a potential consequence of this in a population?

Accepted Answer

Inbreeding depression, leading to reduced survival and fitness

Question 15

Which of the following is NOT a direct effect of genetic drift?

Accepted Answer

Introduction of new alleles into the gene pool

Question 16

Which of the following is a requirement for natural selection to occur in a population?

Accepted Answer

Variation in traits must exist among individuals

Question 17

A population of Northern Elephant Seals was reduced to less than 100 individuals in the late 19th century. After recovery, researchers found no genetic variation in 43 genes sampled. What evolutionary process best explains this observation?

Accepted Answer

Genetic bottleneck effect

Question 18

Which of the following best describes the effect of gene flow on two populations?

Accepted Answer

It makes the populations more genetically similar

Question 19

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

Accepted Answer

Gene flow between populations

Question 20

Which of the following is an example of a missense mutation?

Accepted Answer

A mutation that results in a change from one amino acid to another

Mechanisms of Evolution: How Allele Frequencies Change in Populations

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