Chapter 23: the Evolution of Populations

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Biology, 7e (Campbell)
Chapter 23: The Evolution of Populations

Chapter Questions

1) What is the most important missing evidence or observation in Darwin's theory of 1859? A) the source of genetic variation
B) evidence of the overproduction of offspring
C) evidence that some organisms became extinct
D) observation that variation is common in populations
E) observation that competition exists in populations
Answer: A
Topic: Concept 23.1
Skill: Knowledge

2) Which hypothesis of inheritance, common at Darwin's time, caused many to question the ability of natural selection to bring about adaptation in populations? A) particulate hypothesis
B) blending hypothesis
C) chromosomal hypothesis
D) nucleic acid hypothesis
E) proofreading hypothesis
Answer: B
Topic: Concept 23.1
Skill: Knowledge

3) Which definition of evolution would have been most foreign to Charles Darwin during his lifetime? A) change in gene frequency in gene pools
B) descent with modification
C) the gradual change of a population's heritable traits over generations D) populations becoming better adapted to their environments over the course of generations E) the appearance of new varieties and new species with the passage of time Answer: A

Topic: Concept 23.1
Skill: Knowledge

4) Even in Darwin's time, the blending hypothesis was incompatible with observed facts. If the blending hypothesis were true, then what should one expect to observe over the course of generations? A) Phenotypic polymorphisms should increase.

B) Genetic variation should increase.
C) Members of a breeding population should become more uniform in phenotype. D) Neutral variation should decrease.
E) Genetic polymorphisms should increase.
Answer: C
Topic: Concepts 23.1, 23.4
Skill: Comprehension

5) What is true of the modern evolutionary synthesis?
A) It is about to be declared a scientific law.
B) It is nearing final completion.
C) It has not been able to improve upon Darwin's original ideas about evolution. D) It remains unable to account for Mendel's findings concerning the genetics of pea plants. E) It exemplifies the tentative nature of scientific knowledge. Answer: E

Topic: Concept 23.1
Skill: Knowledge

Use the following information to answer the questions below.

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 36% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants.

6) What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (aa) has not changed over time? A) The population is undergoing genetic drift.

B) The two phenotypes are about equally adaptive under laboratory conditions. C) The genotype AA is lethal.
D) There has been a high rate of mutation of allele A to allele a. E) There has been sexual selection favoring allele a.
Answer: B
Topic: Concept 23.1
Skill: Comprehension

7) What is the estimated frequency of allele a in the gene pool? A) 0.18
B) 0.40
C) 0.60
D) 0.70
E) 0.80
Answer: C
Topic: Concept 23.1
Skill: Application

8) What proportion of the population is probably heterozygous (Aa) for this trait? A) 0.18
B) 0.36
C) 0.48
D) 0.60
E) 0.72
Answer: C
Topic: Concept 23.1
Skill: Application

9) All of the following are criteria for maintaining Hardy-Weinberg equilibrium involving two alleles except A) the frequency of all genotypes must be equal.
B) there should be no natural selection.
C) matings must be random.
D) populations must be large.
E) gene flow from other populations must be zero.
Answer: A
Topic: Concept 23.1
Skill: Comprehension

10) In a Hardy-Weinberg population with two alleles, A and a,...
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