Q: A population of wildflowers has the following genotype counts: 320 red (CRCR), 160 pink (CRCW), and 20 white (CWCW). What is the frequency of the CR allele?

$$\frac{(320 \times 2) + 160}{(320 \times 2) + (160 \times 2) + (20 \times 2)} = \frac{800}{1000} = 0.8$$

Question 1

Which of the following best explains why the average beak depth of medium ground finches increased after a drought, as shown in the provided graph?

Accepted Answer

Natural selection favored finches with larger beaks, increasing their frequency in the population.

Question 2

In the context of evolution, what is the smallest unit that can evolve?

Accepted Answer

A population

Question 3

Which mechanism is the only one that consistently leads to adaptive evolution?

Accepted Answer

Natural selection

Question 4

A population of wildflowers has the following genotype counts: 320 red (CRCR), 160 pink (CRCW), and 20 white (CWCW). What is the frequency of the CR allele?

Accepted Answer

$$\frac{(320 	imes 2) + 160}{(320 	imes 2) + (160 	imes 2) + (20 	imes 2)} = \frac{800}{1000} = 0.8$$

Question 5

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

Accepted Answer

Small population size

Question 6

If $$p$$ and $$q$$ represent the frequencies of two alleles at a locus, which equation describes the expected genotype frequencies in Hardy-Weinberg equilibrium?

Accepted Answer

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

Question 7

Which evolutionary mechanism is illustrated when a few individuals colonize a new area and their allele frequencies differ from the original population?

Accepted Answer

Founder effect

Question 8

In alligators, the sex of offspring is determined by the temperature at which eggs develop. What type of variation does this represent?

Accepted Answer

Environmental variation

Question 9

Which of the following statements about mutations is TRUE?

Accepted Answer

Mutations in non-coding regions usually result in neutral variation.

Question 10

A population of 10,000 individuals has a disease caused by a recessive allele. If the disease occurs in 1 per 10,000 births, what is the frequency of the recessive allele ($$q$$)?

Accepted Answer

$$q = 0.01$$

Question 11

Which process can lead to a loss of genetic variation and fixation of harmful alleles in a small population?

Accepted Answer

Genetic drift

Question 12

What is the main difference between directional, disruptive, and stabilizing selection?

Accepted Answer

Disruptive selection favors both extremes of the phenotypic range.

Question 13

Which of the following is an example of gene flow?

Accepted Answer

Pollen from one population fertilizing plants in another population.

Question 14

Why does sexual reproduction increase genetic variation in a population?

Accepted Answer

It recombines existing alleles through crossing over, independent assortment, and fertilization.

Question 15

Which of the following best describes relative fitness?

Accepted Answer

The contribution an individual makes to the gene pool of the next generation relative to others.

Question 16

In frequency-dependent selection, the fitness of a phenotype depends on:

Accepted Answer

How common it is in the population.

Question 17

Heterozygote advantage can maintain genetic variation in a population. Which disease is a classic example of this phenomenon?

Accepted Answer

Sickle-cell disease

Question 18

Which statement about natural selection is FALSE?

Accepted Answer

Natural selection always produces perfect organisms.

Question 19

Which of the following is a real-world example of adaptive evolution?

Accepted Answer

Octopuses changing color for camouflage.

Question 20

If a population is in Hardy-Weinberg equilibrium, what can be inferred about the evolutionary forces acting on it?

Accepted Answer

No evolutionary forces are acting on the population at that locus.

Chapter 23: The Evolution of Populations – Study Notes

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