Question 1

Which of the following best explains why population thinking, rather than typological thinking, is central to understanding evolution by natural selection?

Accepted Answer

Population thinking recognizes that variation among individuals in a population is the raw material for evolution.

Question 2

A population of bacteria is exposed to an antibiotic. After several generations, most bacteria are resistant. Which of Darwin’s postulates does this scenario best illustrate?

Accepted Answer

Individuals with heritable traits that confer resistance survive and reproduce more successfully.

Question 3

Which of the following is an example of a vestigial structure?

Accepted Answer

The human appendix, which has lost most of its original digestive function.

Question 4

Which equation 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 5

A population of 1000 individuals has 360 with genotype AA, 480 with Aa, and 160 with aa. What is the frequency of allele a?

Accepted Answer

$q = 0.4$

Question 6

Which of the following evolutionary processes always increases genetic variation in a population?

Accepted Answer

Mutation

Question 7

Which pattern of natural selection is most likely to result in the formation of two distinct phenotypes within a population?

Accepted Answer

Disruptive selection

Question 8

Which of the following best describes the founder effect?

Accepted Answer

A small group of individuals establishes a new population with a gene pool that differs from the original population.

Question 9

Which of the following is a postzygotic reproductive barrier?

Accepted Answer

Hybrid offspring are sterile.

Question 10

Which species concept is most useful for identifying cryptic species that are morphologically similar but genetically distinct?

Accepted Answer

Phylogenetic species concept

Question 11

Which of the following best distinguishes allopatric speciation by vicariance from allopatric speciation by dispersal?

Accepted Answer

Vicariance involves a physical barrier splitting a population; dispersal involves a subset of individuals colonizing a new area.

Question 12

Which of the following is an example of sympatric speciation?

Accepted Answer

A population of plants undergoes polyploidization, resulting in a new species within the same geographic area.

Question 13

Which of the following terms refers to a group that includes an ancestor and all of its descendants on a phylogenetic tree?

Accepted Answer

Monophyletic group (clade)

Question 14

Why is distinguishing between homology and homoplasy important when constructing phylogenetic trees?

Accepted Answer

Homology indicates shared ancestry, while homoplasy results from convergent evolution and can mislead tree construction.

Question 15

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

Accepted Answer

Natural selection is acting on the population.

Question 16

A population of frogs is split by a new highway, preventing gene flow. Over time, the two groups accumulate genetic differences. Which evolutionary process is primarily responsible for this divergence?

Accepted Answer

Genetic drift and natural selection

Question 17

Which of the following best describes balancing selection?

Accepted Answer

It maintains genetic diversity in a population by favoring heterozygotes or multiple alleles.

Question 18

Which of the following is a source of new genetic variation in a population?

Accepted Answer

Point mutations

Question 19

Which outcome is most likely if hybrids in a hybrid zone have lower fitness than either parent species?

Accepted Answer

Reinforcement of reproductive barriers

Question 20

Which principle is used to select the simplest phylogenetic tree that explains the observed data?

Accepted Answer

Parsimony

Study Guidance for Evolution, Speciation, and Phylogenies (Biology)

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