Question 1

A researcher rolls a fair six-sided die 120 times and records the following results: 1 (5), 2 (10), 3 (20), 4 (30), 5 (45), 6 (10). Which statistical test would best help determine if the die is loaded, and what is the null hypothesis?

Accepted Answer

A chi-square test; the null hypothesis is that the observed frequencies match the expected frequencies for a fair die.

Question 2

Which of the following best describes 'relative fitness' in an evolutionary context?

Accepted Answer

The contribution an individual makes to the gene pool of the next generation compared to other individuals.

Question 3

Which mode of selection is illustrated when the mean phenotype of a population shifts toward one extreme after several generations?

Accepted Answer

Directional selection

Question 4

In a population of birds, individuals with very small or very large beaks are favored over those with medium-sized beaks. Which mode of selection is this?

Accepted Answer

Disruptive selection

Question 5

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

Accepted Answer

The maintenance of average human birth weight due to higher mortality of very small and very large babies.

Question 6

A population of fish is exposed to a new predator that only preys on individuals of intermediate size. Over time, the population evolves to have mostly very small and very large individuals. What has occurred?

Accepted Answer

Disruptive selection

Question 7

Which of the following statements about sexual selection is correct?

Accepted Answer

Sexual selection can lead to traits that decrease survival but increase mating success.

Question 8

Why is 'female choice' more common in intersexual selection?

Accepted Answer

Females usually have a higher reproductive investment than males.

Question 9

Which of the following best describes artificial selection?

Accepted Answer

Humans breed organisms to enhance desirable traits.

Question 10

A population of plants is exposed to drought, and over several generations, the average root depth increases. Which equation would you use to calculate the change in mean phenotype, and what does it represent?

Accepted Answer

Use $$\Delta \bar{x} = h^2$ S$$, which represents the response to selection.

Question 11

Which of the following is a misleading term in evolutionary biology, and why?

Accepted Answer

'Survival of the fittest,' because it implies only the strongest survive, rather than those best suited to their environment.

Question 12

In a chi-square test, what does the 'degrees of freedom' (df) represent?

Accepted Answer

The number of categories minus one.

Question 13

Which scenario best illustrates intrasexual selection?

Accepted Answer

Male deer fighting for access to females.

Question 14

Which of the following is an example of sexual dimorphism?

Accepted Answer

Male peacocks having large, colorful tails while females are brown and smaller.

Question 15

A scientist is testing whether a population of plants has undergone artificial selection for flower color. Which of the following would provide the strongest evidence?

Accepted Answer

A consistent increase in the frequency of a specific flower color over multiple generations due to human breeding.

Question 16

Which of the following best explains why the mean phenotype does not change during stabilizing selection?

Accepted Answer

Both extremes are selected against, so the average remains the same but variation decreases.

Question 17

Which hypothesis explains why females may prefer males with exaggerated traits, such as bright plumage or elaborate dances?

Accepted Answer

Good genes and sexy sons hypotheses.

Question 18

A population of moths is exposed to pollution, causing tree bark to darken. Over time, the frequency of dark-colored moths increases. Which mode of selection is this, and why?

Accepted Answer

Directional selection, because one extreme phenotype is favored.

Question 19

Which equation would you use to calculate the chi-square statistic for a set of observed and expected values?

Accepted Answer

$$\$$chi^2$$ = \sum \frac{(O-E)^2$}{E}$$

Modes of Selection and Evolutionary Mechanisms

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