Question 1

Which of the following best explains why tuberculosis (TB) remains a significant health threat despite the availability of antibiotics?

Accepted Answer

Some strains of Mycobacterium tuberculosis have evolved resistance to antibiotics through natural selection.

Question 2

Which of the following is NOT one of Darwin’s four observations that led to the inference of natural selection?

Accepted Answer

Survival and reproduction are random.

Question 3

A population of insects is exposed to a new pesticide. After several generations, most of the population is resistant to the pesticide. Which process best explains this outcome?

Accepted Answer

Natural selection

Question 4

Why does natural selection not result in 'perfectly adapted' organisms?

Accepted Answer

Natural selection only acts on traits already present in the population and environments can change.

Question 5

Which of the following is an example of artificial selection?

Accepted Answer

The breeding of horses for racing

Question 6

In a laboratory experiment, fruit flies are exposed to high concentrations of alcohol. Over 57 generations, the percentage of flies that can metabolize alcohol quickly increases. What does this demonstrate?

Accepted Answer

Natural selection favoring alcohol-metabolizing variants

Question 7

Which pattern of selection results in the population mean shifting toward one extreme phenotype?

Accepted Answer

Directional selection

Question 8

Why is combination drug therapy (using multiple antibiotics at once) more effective at preventing the evolution of drug-resistant bacteria than single-drug therapy?

Accepted Answer

It reduces the chance that a single bacterium will possess resistance to all drugs simultaneously.

Question 9

Which of the following best describes the concept of 'fitness' in evolutionary biology?

Accepted Answer

The ability of an organism to survive and reproduce relative to others in the population.

Question 10

A population of blue mussels develops thicker shells after the introduction of an invasive crab species. Which type of selection is most likely responsible for this change?

Accepted Answer

Directional selection

Question 11

Which of the following statements about mutations is correct?

Accepted Answer

Mutations are the original source of new alleles in a population.

Question 12

Why is it important to complete the full course of antibiotics when treating a bacterial infection like TB?

Accepted Answer

Stopping early allows surviving bacteria, possibly with resistance, to multiply.

Question 13

Which of the following is a real-world example of stabilizing selection?

Accepted Answer

Human birth weight, where very low and very high weights have higher mortality.

Question 14

Which of the following best describes the modern synthesis in evolutionary biology?

Accepted Answer

The combination of Mendelian genetics with Darwinian evolution.

Question 15

If a trait increases the number of offspring produced but does not affect survival, what is this trait considered?

Accepted Answer

An adaptation

Question 16

Which of the following is a common misunderstanding about natural selection?

Accepted Answer

Natural selection causes new traits to arise when needed.

Question 17

A population of birds has two distinct beak sizes, small and large, with few intermediates. Which pattern of selection is most likely occurring?

Accepted Answer

Diversifying (disruptive) selection

Question 18

Which equation best represents the change in allele frequency due to natural selection in a population?

Accepted Answer

$$p' = \frac{p w_A}{\overline{w}}$$

Question 19

Why can’t humans simply evolve resistance to tuberculosis as quickly as bacteria evolve resistance to antibiotics?

Accepted Answer

Most humans are never exposed to TB, and human generations are much longer than bacterial generations.

Question 20

Which of the following best describes evolution by natural selection?

Accepted Answer

A change in the traits of individuals in a population over generations due to differential survival and reproduction.

Chapter 12: An Evolving Enemy – Natural Selection and Tuberculosis

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