Biology

1
Biology

• Ch. 16 Review

2
Which of the following statements describe what
all members of a population share?

1. They are temporally isolated from each other.
2. They are geographically isolated from each other.
3. They are members of the same species.
4. They have identical genes.

3
All the genes of all members of a particular
population make up the populations

1. relative frequency.
2. phenotype.
3. genotype.
4. gene pool.

4
Which statement below about gene pools is
typically true?

1. They contain two or more alleles for each
   inheritable trait.
2. They contain only dominant alleles.
3. They belong to two or more interbreeding species.
4. The relative frequencies of the alleles never
   change.

5
If an allele makes up one fourth of a
populations alleles for a given trait, its
relative frequency is

1. 100 percent.
2. 75 percent.
3. 25 percent.
4. 4 percent.

6
Interbreeding among members of a population
results in

1. different types of alleles in the gene pool.
2. changes in the relative frequencies of alleles in
   the gene pool.
3. no changes in the relative frequencies of alleles
   in the gene pool.
4. an absence of genetic variation in the population.

7
In a population, the sum of the relative
frequencies of all alleles for a particular trait
is

1. equal to 100 percent.
2. equal to the number of alleles for the trait.
3. constantly changing.
4. dependent on the number of alleles.

8
A change in a sequence of DNA is called a

1. recombination.
2. polygenic trait.
3. single-gene trait.
4. mutation.

9
The two main sources of genetic variation are

1. genotypes and phenotypes.
2. gene shuffling and mutations.
3. single-gene traits and polygenic traits.
4. directional selection and disruptive selection.

10
In many kinds of organisms, inheritable
differences are due mostly to

1. mutations during gamete formation.
2. polygenic traits.
3. gene shuffling during gamete formation.
4. the effects of radiation.

11
Gene shuffling includes the independent movement
of chromosomes during meoisis as well as

1. mutations from radiation.
2. changes in the frequencies of alleles.
3. crossing-over.
4. mutations from chemicals.

12
In a particular population, sexual reproduction
can produce

1. mutations.
2. many different phenotypes.
3. new allele frequencies.
4. meiosis.

13
The gene shuffling that occurs as part of sexual
reproduction

1. changes the gene pools allele frequencies.
2. does not change the gene pools allele
   frequencies.
3. keeps the phenotypes consistent.
4. is caused by radiation or chemicals.

14
A single-gene trait that has two alleles and that
shows a simple dominant-recessive pattern
will result in

1. one phenotype.
2. two phenotypes.
3. four phenotypes.
4. millions of phenotypes.

15
An example of a single-gene trait is

1. widows peak in humans.
2. weight of human infants at birth.
3. height in humans.
4. beak size in the Galápagos finches.

16
The number of phenotypes produced for a given
trait depends upon

1. the number of genes that control the trait.
2. which form of the trait is dominant.
3. the relative frequencies of the various alleles.
4. the relationship of allele frequencies to
   Mendelian ratios.

17
The phenotypes for a typical polygenic trait can
often be expressed as

1. a bar graph.
2. a bell-shaped curve.
3. Mendelian ratios.
4. allele frequencies.

18
Compared to a polygenic trait, a single-gene
trait tends to have

1. fewer phenotypes.
2. more phenotypes.
3. the same number of phenotypes.
4. phenotypes that form a bell-shaped curve.

19
A polygenic trait can have

1. many possible genotypes, but few possible
   phenotypes.
2. many possible genotypes, producing many possible
   phenotypes.
3. fewer phenotypes than most single-gene traits.
4. fewer genotypes than most single-gene traits.

20
Natural selection acts directly on

1. alleles.
2. genes.
3. phenotypes.
4. mutations.

21
Which of the following is NOT a way in which
natural selection affects the distribution of
phenotypes?

1. directional selection
2. stabilizing selection
3. disruptive selection
4. chance events

22
When individuals at only one end of a bell curve
of phenotype frequencies have high fitness,
the result is

1. directional selection.
2. stabilizing selection.
3. disruptive selection.
4. genetic drift.

23
When individuals with an average form of a trait
have the highest fitness, the result is

1. not predictable.
2. disruptive selection.
3. directional selection.
4. stabilizing selection.

24
In a population of finches in which one group of
birds has a short, parrotlike beak and another
group has a long, narrow beak, what process has
probably occurred?

1. directional selection
2. disruptive selection
3. stabilizing selection
4. genetic drift

25
If a mutation introduces a new skin color in a
lizard population, which factor might determine
whether the frequency of the new allele will
increase?

1. how many other alleles are present
2. whether the mutation makes some lizards more fit
   for their environment than other lizards
3. how many phenotypes the population has
4. whether the mutation was caused by nature or by
   human intervention

26
In genetic drift, allele frequencies change
because of

1. mutations.
2. chance.
3. natural selection.
4. genetic equilibrium.

27
Which of the following events do biologists
consider a random change?

1. directional selection
2. speciation
3. disruptive selection
4. genetic drift

28
Genetic drift tends to occur in populations that

1. are very large.
2. are small.
3. are formed from new species.
4. have unchanging allele frequencies.

29
The type of genetic drift that follows the
colonization of a new habitat by a small group of
individuals is called

1. the Hardy-Weinberg principle.
2. the founder effect.
3. directional selection.
4. stabilizing selection.

30
One similarity between natural selection and
genetic drift is that both events

1. are based completely on chance.
2. begin with one or more mutations.
3. involve a change in a populations allele
   frequencies.
4. take place only in very small groups.

31
The situation in which allele frequencies of a
population remain constant is called

1. evolution.
2. genetic drift.
3. genetic equilibrium.
4. natural selection.

32
One of the conditions required to maintain
genetic equilibrium is

1. natural selection.
2. mutations.
3. nonrandom mating.
4. no movement into or out of the population.

33
The genetic equilibrium of a population can be
disturbed by each of the following EXCEPT

1. nonrandom mating.
2. movement into and out of the population.
3. a large population size.
4. mutations.

34
The allele frequencies of a population are more
likely to remain unchanged if

1. the population size is reduced.
2. frequent movement into and out of the population
   occurs.
3. all mating is random.
4. the mutation rate increases.

35
According to the Hardy-Weinberg principle,
genetic equilibrium would be more likely in a
population of mice if

1. the population size rapidly decreases.
2. mutation rates within the population rise.
3. no natural selection takes place.
4. there is frequent movement into and out of the
   population.

36
Which factor would most likely disrupt genetic
equilibrium in a large population?

1. the production of large numbers of offspring
2. mating that is not random
3. the absence of movement into and out of the
   population
4. the absence of mutations

37
The separation of populations by barriers such as
rivers, mountains, or bodies of water is called

1. temporal isolation.
2. geographic isolation.
3. behavioral isolation.
4. genetic equilibrium.

38
A factor that is necessary for the formation of a
new species is

1. reproduction at different times.
2. geographic barriers.
3. different mating behaviors.
4. reproductive isolation.

39
What situation might develop in a population
having some plants whose flowers open at midday
and other plants whose flowers open late in the
day?

1. behavioral isolation
2. geographic isolation
3. temporal isolation
4. genetic drift

40
The geographic isolation of two populations of a
species tends to increase differences between
their gene pools because it

1. prevents interbreeding between the populations.
2. prevents interbreeding within each population.
3. causes temporal isolation of the two populations.
4. increases differences in courtship behavior.

41
Although they often live in the same habitat, the
American toad breeds earlier in the spring than
the Fowlers toad does. What can be inferred from
this information?

1. The two species do not interbreed because of
   geographic isolation.
2. The two species do not interbreed because of
   temporal isolation.
3. The two species interbreed throughout the spring
   season.
4. The American toad will cause the extinction of
   the Fowlers toad.

42
Which is the first step that occurred in the
speciation of the Galápagos finches?

1. establishing genetic equilibrium
2. behavioral isolation
3. ecological competition
4. arrival of the founding population

43
The Galápagos finch species are an excellent
example of

1. speciation.
2. genetic equilibrium.
3. stabilizing selection.
4. selection on single-gene traits.

44
What did Peter and Rosemary Grant learn about
mate choice from the Galápagos finches?

1. Phenotype plays no role in mate choice.
2. Finches prefer mates with beaks similar in size
   to their own.
3. Finches prefer mates with smaller beaks than
   their own.
4. Finches prefer mates with larger beaks than their
   own.

45
In Rosemary and Peter Grants study of the
Galápagos finches, what process was encouraged by
ecological competition during the dry season?

1. stabilizing selection
2. disruptive selection
3. directional selection
4. genetic drift

46
Which statement about evolution in the Galápagos
finches is true?

1. Natural selection on beak size and shape is
   driven by available food.
2. Stabilizing selection has favored an intermediate
   beak type for all of the finches.
3. Mate choice likely plays no role in the finches
   evolution.
4. None of the finch species is reproductively
   isolated.

47
Because all members of a population can
interbreed, biologists often study their genes as
a single group.

1. True
2. False

48
In a gene pool, as the relative frequency of one
allele for a trait increases, the relative
frequencies of other alleles for that trait
decrease.

1. True
2. False

49
Most inheritable differences are due to mutations
that occur during the production of gametes.

1. True
2. False

50
Mutations do not always affect an organisms
genotypeits physical, behavioral, and
biochemical characteristics.

1. True
2. False

51
A polygenic trait is controlled by one gene.

1. True
2. False

52
On a graph, the distribution of phenotypes for a
single-gene trait tends to form a bell-shaped
curve.

1. True
2. False

53
Natural selection on single-gene traits can lead
to changes in allele frequencies.

1. True
2. False

54
In a population of snakes with a range of body
lengths, if the longest individuals have the
highest fitness, disruptive selection is likely
to occur.

1. True
2. False

55
In small populations, an allele can become more
or less common simply by chance.

1. True
2. False

56
Genetic drift may occur when a small group of
individuals colonize a new habitat.

1. True
2. False

57
When mutations introduce new alleles into a
population, genetic variation is disrupted.

1. True
2. False

58
In a population of birds, if females prefer males
with long tails, the population violates the
condition of directional selection described by
the Hardy-Weinberg principle.

1. True
2. False

59
In the type of reproductive isolation called
behavioral isolation, two populations are
separated by barriers such as rivers or mountains.

1. True
2. False

60
Two populations that have overlapping ranges can
remain reproductively isolated through behavioral
isolation or temporal isolation from each other.

1. True
2. False

61
The first step of the speciation of the Galápagos
finches likely was the arrival of founders from
South America.

1. True
2. False