Question 1

Which of the following statements best describes the smallest unit of evolution?

Accepted Answer

Populations are the smallest unit that can evolve.

Question 2

A population of flowers has two alleles for color: R (red) and r (white). If the frequency of R is $$p = 0.7$$ and the frequency of r is $$q = 0.3$$, what is the expected frequency of heterozygotes ($$Rr) $$under Hardy-Weinberg equilibrium?

Accepted Answer

$$2pq = 0.42$$

Question 3

Which mechanism is the only one that consistently causes adaptive evolution?

Accepted Answer

Natural selection

Question 4

A population of mice experiences a sudden flood that kills most individuals, leaving only a few survivors. This is an example of:

Accepted Answer

Bottleneck effect

Question 5

Which of the following best explains why harmful recessive alleles can persist in a population?

Accepted Answer

They can 'hide' in heterozygous individuals.

Question 6

In a population, the gene pool refers to:

Accepted Answer

The total of all different alleles of all the genes in the population.

Question 7

Which of the following is an example of frequency-dependent selection?

Accepted Answer

The fitness of a phenotype depending on how common it is in the population.

Question 8

Which process introduces new alleles into a population from other populations?

Accepted Answer

Gene flow

Question 9

A population of birds is split into two groups by a mountain range. Over time, the two groups develop different allele frequencies due to random chance. This is an example of:

Accepted Answer

Genetic drift

Question 10

Which of the following is NOT a reason why natural selection cannot produce 'perfect' organisms?

Accepted Answer

Natural selection can create entirely new traits from scratch.

Question 11

Which type of selection favors individuals at both extremes of a trait, potentially leading to two distinct phenotypes?

Accepted Answer

Disruptive selection

Question 12

In a population of flowers, red is dominant to white. If a plant is heterozygous for flower color, what is its genotype?

Accepted Answer

Rr

Question 13

Which of the following mechanisms can increase genetic variation in a population?

Accepted Answer

Mutation

Question 14

If a population is not evolving at a specific gene, what will happen to the allele and genotype frequencies?

Accepted Answer

Both allele and genotype frequencies will remain constant.

Question 15

Which of the following is an example of sexual selection?

Accepted Answer

Male peacocks competing for female attention with elaborate tails.

Question 16

A population of 1000 individuals has 600 alleles for A and 400 alleles for a. What is the frequency of allele a?

Accepted Answer

$$\frac{400}{1000} = 0.4$$

Question 17

Which of the following scenarios would most likely result in a founder effect?

Accepted Answer

A small group of individuals colonizes a new island, carrying only a subset of the original population's alleles.

Question 18

Which of the following is true about heterozygous individuals?

Accepted Answer

They have two different alleles for a gene.

Question 19

Which of the following is a compromise that limits the perfection of adaptations produced by natural selection?

Accepted Answer

Trade-offs between competing functions, such as speed versus strength.

Question 20

Which of the following best describes stabilizing selection?

Accepted Answer

Selection that favors individuals with intermediate traits.

Ch. 21 Evolution of Populations: Mechanisms and Patterns

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Study guide - Flashcard