Chapter 05

Instructions

Choose your answers by clicking the radio button next to each choice and then press 'Submit' to get your score.

Question 01

Which of the following statements about mutations in animals is correct?

a) Germline mutations may have fitness consequences, but somatic mutations have no fitness consequences.

b) Germline mutations may be inherited, but somatic mutations are not inherited.

c) Both germline mutations and somatic mutations can be inherited.

Question 02

Most mutations are a consequence of errors during DNA replication and the rate at which they occur cannot be influenced by natural selection. True or false?

a) True

b) False

Question 03

Selective adjustment of the mutation rate is expected to be easier in asexual than in sexual organisms. True or false?

a) True

b) False

Question 04

Most organisms have DNA genomes, but some viruses have RNA genomes. Which of the following statements is correct?

a) The mutation rates in DNA and RNA genomes is roughly the same.

b) The mutation rate is higher in DNA genomes than in RNA genomes.

c) The mutation rate is higher in RNA genomes than in DNA genomes.

Question 05

Which is more common: mutations with small phenotypic effect or with large phenotypic effect; and dominant or recessive mutations?

a) Most mutations are dominant and have small effects.

b) Most mutations are dominant and have large effects.

c) Most mutations are recessive and have small effects.

d) Most mutations are recessive and have large effects.

Question 06

There is some evidence from data on human genetic diseases that point mutations occur at a higher rate in males than in females. What is a likely explanation?

a) DNA repair works better in females than in males.

b) Female gametes are better protected inside the body than male gametes.

c) The production of male gametes requires many more cell divisions than the production of female gametes.

Question 07

In what respect are mutations occurring randomly?

a) Mutation is random with respect to where it occurs in the genome.

b) Mutation is random with respect to the size of its phenotypic effect.

c) Mutation is random with respect to the relationship between its phenotypic effect and the needs of the organism.

Question 08

Multi-gene families have arisen from:

a) Polyploidization.

b) Gene duplication events.

c) Adaptive modification of originally unrelated genes to a functionally related ensemble.

Question 09

How important is the effect of meiotic recombination on genetic variation?

a) It is mainly important in producing genetic variability between the multi-locus genotpyes in a population.

b) It is mainly important in producing genetic variability at single loci in a population.

c) It has little effect on the total amount of genetic variation in a population.

Question 10

What is a general but fair characterization of the amount of genetic variation at the DNA sequence level occurring in natural populations?

a) Within (diploid) individuals most loci carry identical alleles, heterozygosity is rare.

b) Within (diploid) individuals most loci carry different alleles, heterozygosity is common.

Question 11

How can a comparison of the rates of synonymous and non-synonymous substitution provide insight in the relative importance of natural selection and genetic drift as mechanisms producing genetic variation?

a) In the absence of selection equal rates of synonymous and non-synonymous substitutions are expected; therefore, a preponderance of synonymous substitutions indicates an important role for genetic drift.

b) In the absence of selection synonymous substitutions are expected to be several times more frequent than non-synonymous substitutions; therefore, a preponderance of synonymous substitutions does not exclude an important role for selection.

Question 12

A general conclusion about the most likely explanation of the observed high amounts of molecular genetic variation in populations, based on a large number of studies, is:

a) most variation is selectively neutral, therefore genetic drift is the main explanation of observed molecular genetic variation.

b) most variation is not selectively neutral, therefore natural selection is the main explanation of observed molecular genetic variation.

c) evidence points to the existence of both (near-) neutrality and non-neutrality of genetic variation; therefore genetic drift as well as natural selection play an important role.

Question 13

Which mode of natural selection is most important in maintaining genetic variation at single loci?

a) Overdominance

b) Positive frequency-dependent selection

c) Negative frequency-dependent selection

d) Underdominance

Question 14

Which type of selection has been shown to be responsible for the stable maintenance of the hemoglobin polymorphism associated with malaria?

a) Overdominance

b) Negative frequency-dependent selection

Question 15

The maintenance of quantitative genetic variation (involved in quantitative traits) is most likely maintained by which of the following?

a) A combination of overdominance and negative frequency-dependent selection.

b) A combination of mutation and stabilizing selection.

c) A combination of mutation and genetic drift.