Life: The Science of Biology

David E. Sadava, David M. Hilliss, H. Craig Heller,May Berenbaum

Chapter 21

Evidence and Mechanisms of Evolution - all with Video Answers

Educators

Chapter Questions

Problem 1

Long-horned cattle have greater difficulty moving through heavily forested areas compared with cattle that have short or no horns, but long-horned cattle are better able to defend their young against predators. This contrast is an example of
$a$. an adaptation.
$b$. genetic drift.
c. natural selection.
$d .$ a trade-off.
$e .$ none of the above

Aditya Sood

Aditya Sood

Numerade Educator

Problem 2

Which of the following is true?
a. Darwin and Wallace were both influenced by Malthus.
b. Wallace proposed a theory of evolution by natural selection that was similar to Darwin's.
c. Malthus claimed that because human population growth would outstrip any increases in food production, famine was a likely result.
d. Darwin realized that all populations had the capacity to rapidly increase in numbers.
$e .$ All of the above

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 3

The phenotype of an organism is
$a$. the type specimen of its species in a museum.
$b$, its genetic constitution, which governs its traits.
$c .$ the chronological expression of its genes.
$d$. the physical expression of its genotype.
$e .$ its adult form.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 4

The appropriate unit for defining and measuring genetic variation is the
a. cell.
b. individual.
c. population.
$d .$ community.
$e .$ ecosystem.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 5

Which statement about allele frequencies is not true?
a. The sum of all allele frequencies at a locus is always 1
$b .$ If there are two alleles at a locus and we know the frequency of one of them, we can obtain the frequency of the other by subtraction.
$c .$ If an allele is missing from a population, its frequency in that population is 0
d. If two populations have the same allele frequencies at a locus, they must have the same proportion of homozygotes at that locus.
$e .$ If there is only one allele at a locus, its frequency is 1

Alexander Cheng

Alexander Cheng

Numerade Educator

Problem 6

Which of the following is not required for a population at Hardy-Weinberg equilibrium?
$a .$ There is no migration between populations.
$b .$ Natural selection is not acting on the alleles in the population.
c. Mating is random.
d. Multiple alleles must be present at every locus.
$e .$ All of the above.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 7

The fitness of a genotype is a function of the
a. average rates of survival and reproduction of individuals
with that genotype.
$b$. individuals that have the highest rates of both survival and reproduction.
$c .$ individuals that have the highest rates of survival.
$d$. individuals that have the highest rates of reproduction.
$e .$ average reproductive rate of individuals with that genotype.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 8

Laboratory selection experiments with fruit flies have demonstrated that
$a$. bristle number is not genetically controlled.
$b .$ bristle number is not genetically controlled, but changes in bristle number are caused by the environment in which the fly is raised.
$c .$ bristle number is genetically controlled, but there is little variation on which natural selection can act.
$d$. bristle number is genetically controlled, but selection cannot result in flies having more bristles than any individual in the original population had.
$e .$ bristle number is genetically controlled, and selection can result in flies having more, or fewer, bristles than any individual in the original population had.

Bryan Lynn

Numerade Educator

Problem 9

Disruptive selection maintains a bimodal distribution of bill size in the West African seedcracker because
a. bills of intermediate shapes are difficult to form.
$b .$ the birds' two major food sources differ markedly in size and hardness.
$c .$ males use their large bills in displays.
$d$. migrants introduce different bill sizes into the population each year.
e. older birds need larger bills than younger birds.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 10

Which of the following is not a reason why trade-offs constrain evolution?
a. Most adaptations impose both fitness costs and benefits.
b. Structures such a horns and antlers are metabolically costly to produce, but result in more reproduction by the males that possess them.
c. Changes in allele frequencies may be influenced by chance events.
$d$. Ability to consume toxic prey may reduce mobility.
e. Adaptations can evolve only if the fitness benefits they confer exceed the costs they impose.

Christina Sorrentino

Christina Sorrentino

Numerade Educator