Question 1

Which evolutionary process is best illustrated by the sudden reduction in population size and genetic diversity following a natural disaster, as shown in the before-and-after satellite images of Banda Aceh, Indonesia?

Accepted Answer

Population bottleneck

Question 2

In a laboratory experiment, a population of fruit flies with two alleles for bristle type (normal and forked) is split into 96 small populations. Over several generations, most populations lose one allele. Which process is responsible for this outcome?

Accepted Answer

Genetic drift

Question 3

Why does genetic drift have a stronger effect in small populations compared to large populations, as shown in the allele frequency graphs for population sizes of 4 and 400?

Accepted Answer

Random sampling errors have a greater impact when there are fewer individuals.

Question 4

A group of plants is separated by a mountain range, and over time, the two populations develop different allele frequencies due to lack of interbreeding. Which process is primarily responsible for the genetic divergence?

Accepted Answer

Restriction of gene flow

Question 5

In the experiment with E. coli bacteria, what was the main evolutionary force responsible for the observed increases in average fitness over 2,000 generations?

Accepted Answer

Mutation followed by natural selection

Question 6

Which type of natural selection is illustrated by the shift in average body size of cliff swallows after a cold snap, as shown in the histogram with the arrow pointing to larger body sizes?

Accepted Answer

Directional selection

Question 7

A population of birds experiences high mortality in both very small and very large newborns, resulting in most surviving individuals having intermediate birth weights. Which pattern of selection does this describe?

Accepted Answer

Stabilizing selection

Question 8

In a population of seedcrackers, only individuals with very long or very short beaks survive to reproduce, while those with intermediate beak lengths are selected against. What is the likely evolutionary outcome if this pattern continues?

Accepted Answer

The population may split into two subgroups, potentially leading to speciation.

Question 9

Which of the following best explains why mutation is considered the ultimate source of genetic variation in populations?

Accepted Answer

Mutation introduces new alleles into every population in every generation.

Question 10

A population of snakes exhibits two distinct color patterns, both of which are favored in different environments, while intermediate patterns are rare. Which type of selection is most likely acting on this trait?

Accepted Answer

Disruptive (diversifying) selection

Question 11

In a population of beetles, a random event kills most of the green beetles, leaving mostly brown beetles to reproduce. Which evolutionary process is illustrated by this scenario?

Accepted Answer

Genetic drift (bottleneck effect)

Question 12

Which of the following statements about gene flow is correct?

Accepted Answer

Gene flow tends to equalize allele frequencies between populations.

Question 13

Which scenario best exemplifies the founder effect?

Accepted Answer

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

Question 14

Which of the following is a consequence of inbreeding in a population?

Accepted Answer

Inbreeding increases the frequency of homozygotes and can lead to inbreeding depression.

Question 15

Sexual selection often leads to sexual dimorphism. Which of the following is an example of sexual dimorphism?

Accepted Answer

Males and females of a species have different physical traits, such as size or coloration.

Question 16

Which of the following best describes the relationship between mutation and natural selection?

Accepted Answer

Mutation introduces new genetic variation, which natural selection can then act upon.

Question 17

A population of plants shows a gradual change in height along an elevation gradient, as shown in the cline diagram. What is the most likely explanation for this pattern?

Accepted Answer

Environmental variation (cline)

Question 18

Which of the following equations represents the Hardy-Weinberg equilibrium for a gene with two alleles, $$A_1$$ and $$A_2$$, with frequencies $$p$$ and $$q$$?

Accepted Answer

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

Question 19

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

Accepted Answer

Nonrandom mating

Question 20

In a population of crabs, males have one large claw used to attract females, while females have two small claws. Which evolutionary process is most likely responsible for this difference?

Accepted Answer

Sexual selection

Processes of Evolution: Adaptive and Non-Adaptive Mechanisms

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