Q: A population of 100 plants has the following genotype counts for a flower color gene: 36 red (RR), 48 pink (Rr), and 16 white (rr). What is the frequency of the r allele in this population?

$$\frac{48 + 2 \times 16}{2 \times 100} = \frac{48 + 32}{200} = \frac{80}{200} = 0.4$$

Q: In a population in Hardy-Weinberg equilibrium, the frequency of allele $$E is 0.8. $$What is the expected frequency of the genotype $$Ee$$?

$$2pq = 2 \times 0.8 \times 0.2 = 0.32$$

Q: If 9% of an African population has sickle cell disease (homozygous recessive), what percentage of the population is malaria resistant due to heterozygote advantage?

$$2pq = 2 \times 0.7 \times 0.3 = 0.42 or 42$$%

Question 1

Which of the following best explains why genetic variation within a population is necessary for natural selection to occur?

Accepted Answer

Genetic variation allows individuals to adapt to changing environments, increasing the likelihood that some will survive and reproduce.

Question 2

A population of 100 plants has the following genotype counts for a flower color gene: 36 red (RR), 48 pink (Rr), and 16 white (rr). What is the frequency of the r allele in this population?

Accepted Answer

$$\frac{48 + 2 	imes 16}{2 	imes 100} = \frac{48 + 32}{200} = \frac{80}{200} = 0.4$$

Question 3

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

Accepted Answer

Small population size

Question 4

In a population in Hardy-Weinberg equilibrium, the frequency of allele $$E is 0.8. $$What is the expected frequency of the genotype $$Ee$$?

Accepted Answer

$$2pq = 2 	imes 0.8 	imes 0.2 = 0.32$$

Question 5

Which pattern of natural selection is illustrated when individuals with intermediate phenotypes have higher fitness than those with extreme phenotypes?

Accepted Answer

Stabilizing selection

Question 6

A population of birds experiences a sudden environmental disaster that drastically reduces its size. The surviving population has much less genetic variation than the original. What evolutionary process has occurred?

Accepted Answer

Genetic drift via bottleneck effect

Question 7

Which of the following scenarios best describes disruptive selection?

Accepted Answer

A population of fish in a lake where both very small and very large individuals survive better than medium-sized ones due to different predators.

Question 8

Which of the following is an example of intersexual selection?

Accepted Answer

Female peacocks choosing males with the brightest feathers.

Question 9

If 9% of an African population has sickle cell disease (homozygous recessive), what percentage of the population is malaria resistant due to heterozygote advantage?

Accepted Answer

$$2pq = 2 	imes 0.7 	imes 0.3 = 0.42 or 42$$%

Question 10

Which evolutionary process tends to reduce differences in allele frequencies between two populations?

Accepted Answer

Migration (gene flow)

Question 11

A small group of lizards migrates to a new island and establishes a population. Over time, their allele frequencies differ markedly from the original population. What is this phenomenon called?

Accepted Answer

Founder effect

Question 12

Which of the following statements about genetic drift is TRUE?

Accepted Answer

Genetic drift has a greater effect in small populations than in large populations.

Question 13

In a population in Hardy-Weinberg equilibrium, if the frequency of the recessive allele $$q is 0.3$$, what is the expected frequency of homozygous recessive individuals?

Accepted Answer

$$q^2$$ = $$0.3^2 = 0.09$

Question 14

Which of the following mechanisms can maintain genetic diversity in a population over many generations?

Accepted Answer

Balancing selection

Question 15

Which of the following is a direct measure of an individual's fitness in evolutionary terms?

Accepted Answer

The number of offspring that survive to reproduce

Question 16

A population of bacteria is exposed to an antibiotic. Over time, only those with high resistance survive and reproduce. Which pattern of natural selection is this?

Accepted Answer

Directional selection

Question 17

Which of the following best describes frequency-dependent selection?

Accepted Answer

The fitness of a phenotype depends on how common it is in the population.

Question 18

Which of the following would cause a population to deviate from Hardy-Weinberg equilibrium?

Accepted Answer

Non-random mating

Question 19

A gene in a population is polymorphic. What does this mean?

Accepted Answer

There are two or more alleles for the gene in the population.

Question 20

Which of the following is most likely to increase genetic diversity within a population?

Accepted Answer

Migration (gene flow) from other populations

Evolution of Populations: Population Genetics and Mechanisms of Evolution

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