Into to evolution/ Population genetics

Question 1

In order for natural selection to occur within a population, certain conditions must be met. One condition is

heterozygosity must be very low.
phenotypic variations that are genetic.
frequent mutations that are inherited.
low rates of immigration.

Answer 1

phenotypic variations that are genetic.

Question 2

In the phalarope, or wade pipes bird, the male is unusual in playing the larger parenting role – he performs all the egg incubation and chick care. What unusual behavior might you predict for the female of the species?

The female is part of a large harem of females, under the domain of a single male.
The females compete to mate with the males, who choose among them.
The female provides sperm to fertilize the male’s eggs.
The females have dull, brown coloring that keeps them well-camouflaged.

Answer 2

The females compete to mate with the males, who choose among them.

Question 3

Darwin proposed that natural selection occurs in an environment by

favoring heritable features that make the organism better suited to survive and reproduce.
producing a constant number of offspring while in that environment.
surviving for a fixed amount of time.
favoring those individuals with the most favorable acquired characteristics.

Answer 3

favoring heritable features that make the organism better suited to survive and reproduce.

Question 4

When the function of an allele is influenced by the alleles of other genes elsewhere in the genome, the interaction is called _________and can affect selection for the allele.

incomplete dominance
epistasis
frequency-dependent selection
pleiotropy

Answer 4

epistasis

Question 5

Some flowering plants cannot self-pollinate which increases their tendency to mate with phenotypically different mates, a process called disassortative mating. What effect would this have on a population, compared to expectations based on the Hardy-Weinberg principle?

A decrease in heterozygotes would be observed.
An increase in heterozygotes would be observed.
No change homozygotes or heterozygotes would be observed.
The population would remain in Hardy-Weinberg equilibrium.

Answer 5

An increase in heterozygotes would be observed.

Question 6

In some instances environmental change causes a situation where one phenotype is favored for a period of time, and then a different phenotype is favored. This oscillating selection causes

extinction of the population.
the maintenance of genetic variation in the population.
high population increase to maintain phenotypic variation.
elimination of rarer genotypes because of uneven selection.

Answer 6

the maintenance of genetic variation in the population.

Question 7

Genotypes are said to be in _________ equilibrium if there is random mating and no other forces tend to alter the proportions of alleles from one generation to the next.

Hardy-Weinberg
Mendelian
frequency-dependent
homeostatic

Answer 7

Hardy-Weinberg

Question 8

Being born with extra fingers on a hand is called polydactyly. This is more common in some populations in North America than others due to _________.

an increase in mutation rate in these populations
random mating with other populations in North America
migration of people with multiple fingers out of the population
a founder effect because their ancestors from Europe carried the alleles

Answer 8

a founder effect because their ancestors from Europe carried the alleles

Question 9

People homozygous for the sickle-cell anemia allele develop a life-threatening disease, while those homozygous for the normal allele are at the highest risk of dying from malaria. Carriers have some resistance to malaria but do not develop sickle cell anemia. This is an example of _________

genetic bottleneck.
heterozygote advantage.
point mutation.
founder effect.

Answer 9

heterozygote advantage.

Question 10

Since females take on the larger parenting role in most species, what tendency do they have?

They fight for territory.
They produce large numbers of gametes.
They are the choosy sex.
They acquire polyandrous groups of male mates.

Answer 10

They are the choosy sex.

Question 11

Animals that select mates that are phenotypically similar will have _________ when compared with Hardy-Weinberg predictions.

less natural selection
more heterozygotes
more mutations
more homozygotes.

Answer 11

more homozygotes.

Question 12

The organism with the highest fitness is:

An animal that lives 10 years and produces 2 offspring per year.
An animal that lives one year and produces 10 offspring total.
An animal that lives 100 years and produces 10 offspring total.
An animal that lives 10 years and produces 10 offspring per year.

Answer 12

An animal that lives 10 years and produces 10 offspring per year.

Question 13

Reproductive success of an individual is known as:

fitness.
variation.
microevolution.
adaptive makeup.

Answer 13

fitness.

Question 14

Two parents who do not have sickle cell anemia have a child that has the disease. The parents are both:

pleiotropic for the sickle cell allele.
epistatic for the sickle cell allele.
heterozygous for the sickle cell allele.
homozygous for the normal allele.

Answer 14

heterozygous for the sickle cell allele.

Question 15

By evaluating and selecting mates with superior qualities, an animal can increase its

foraging efficiency.
competitive strategies.
reproductive success.
length of life.

Answer 15

reproductive success.

Question 16

Cheetahs have been through a genetic bottleneck; evidence for this is that

these cats are members of an endangered species.
they originally came from small areas of Africa.
little natural selection occurs in this species.
there is very little genetic variability.

Answer 16

there is very little genetic variability.

Question 17

There are more than 30 blood group genes in humans, in addition to the ABO locus, each with multiple alleles. This increases ____ in human populations.

gene flow
genetic variability
homozygosity
founder effects

Answer 17

genetic variability

Question 18

The disease sickle-cell anemia is common in malaria-infested areas because individuals that are heterozygous for the gene (AS) have enhanced resistance to malaria compared to other individuals (AA). Individuals with severe sickle-cell anemia (SS) often die before reproduction. If this population moves to an area without malaria, what will happen to the allele frequency of the A allele over time?

It will go down because there is no malaria.
It will go up because there is no malaria.
It will go down because there are diseases of some kind everywhere.
It will go up because there is no sickle cell anemia.

Answer 18

It will go up because there is no malaria.

Question 19

The frequency of a particular allele within a population can be changed, over time, by

genetic outflow.
large population size.
selection.
inheritance of acquired characteristics.

Answer 19

selection.

Question 20

For a gene with two alternative alleles, B and b, the term q2 in the Hardy-Weinberg equation represents

the frequency of the Bb genotype.
the total number of individuals in the population.
the frequency of the bb genotype.
the frequency of the B allele.

Answer 20

the frequency of the bb genotype.

Question 21

In a forest, trees that grow taller get more sunlight and gain more energy than other nearby trees. This results in _________

directional selection.
artificial selection.
stabilizing selection.
disruptive selection.

Answer 21

directional selection.

Question 22

For a gene with two alternative alleles, A (with a frequency of p) and a (with a frequency of q), the term in the algebraic form of the Hardy-Weinberg equilibrium for the heterozygote genotype frequency is

(p+q)2.
p2.
2pq.
q2.

Answer 22

2pq.

Question 23

Platys and swordtails are related tropical freshwater fish. In studies, researchers have shown that female platys prefer males with swordtails, even though males of their own species do not have them. This was discovered by attaching artificial swordtails to platy males. What does this suggest about the origin of the swordtail feature?

Female preference for swords may have predated the origin of the feature itself.
Evolution of swords later led to evolution of female preference for swords.
Adjacent genes on the same chromosome cause sword development and development of neural circuits for female preference.
The same gene that causes sword development also causes development of neural circuits for female preference.

Answer 23

Female preference for swords may have predated the origin of the feature itself.

Question 24

You spray your kitchen with an insecticide to kill the cockroaches. A few survive and reproduce, producing a large healthy population in a few generations that all have similar genetic backgrounds. This is an example of _________

bottleneck effect.
migration.
gene flow.
assortative mating.

Answer 24

bottleneck effect

Question 25

In a large population of randomly reproducing rabbits, a recessive allele r comprises 80% of the alleles for a gene. What percentage of the rabbits would you expect to have the recessive phenotype?

32%
90%
64%
80%

Answer 25

64%

Question 26

An insect population that becomes resistant to a plant’s toxin is an example of _________.

genetic drift
gene flow
natural selection
disruptive selection

Answer 26

natural selection

Question 27

A study finds a positive correlation between the number of spots on the tails of male peacocks and their mating success. What would be the best follow-up experiment to test causation?

Measure the sperm count of males and compare to spot count.
Inject testosterone and observe changes in spot count.
Count the number of spots on female tails and measure mating success.
Remove spots or add artificial spots to male tails and determine female responses.

Answer 27

Remove spots or add artificial spots to male tails and determine female responses.

Question 28

About 80% of the alleles present in thoroughbred horses can be dated back to 31 known ancestors from the late eighteenth century. As a result, one would expect _________

little variation to select upon.
low rates of mutation.
random mating.
Hardy-Weinberg equilibrium.

Answer 28

little variation to select upon.

Question 29

When fisheries managers move fish from one lake to another, this causes gene _________.

flow
blending
mutation
dominance

Answer 29

flow

Question 30

If a population was in Hardy-Weinberg equilibrium, then _________would occur in that population.

directional selection
no evolutionary changes
assortative mating
natural selection

Answer 30

no evolutionary changes

Question 31

The recessive phenotype of a trait occurs in 16% of a population. What is the frequency of the dominant allele?

0.40
0.16
0.60
0.48

Answer 31

0.60

Question 32

A certain island is the home of sea birds that migrate, as well as ground-dwelling birds that stay on the island. The ground-dwelling birds are more likely to be in Hardy-Weinberg equilibrium than the sea birds, because:

the sea birds are more exposed to UV light.
of high immigration in the sea bird population.
natural selection is stronger in the ground-dwelling birds.
mating is random in the sea birds.

Answer 32

of high immigration in the sea bird population.

Question 33

Coloration in the peppered moth (Biston betularia) is determined by a single gene with two alleles showing complete dominance. Dark moths are homozygous dominant or heterozygous for the gene, light moths are homozygous recessive. In a sample of 100 moths, you determine that 64 of the moths are dark. According to the Hardy-Weinberg rule, the expected frequency of the dominant allele is ___.

0.4
0.64
0.36
0.6

Answer 33

0.4

Question 34

In disruptive selection, over time

the population is strongly selected for in two directions (e.g., larger beak size and smaller beak size).
a population goes extinct.
the most extreme outliers of a population are eliminated (e.g., the largest beaks and smallest beaks are eliminated).
a population increases its variation (e.g., a wide selection of all beak sizes).

Answer 34

the population is strongly selected for in two directions (e.g., larger beak size and smaller beak size).

Question 35

Many male songbirds are brightly colored. However, the color of the birds is determined by a balance of

natural selection against bright colors by predation and mutations that introduce bright colors.
mutations that reduce bright colors and sexual selection in favor of bright colors.
natural selection against bright colors by predation and sexual selection in favor of bright colors.
mutations that reduce bright colors and gene flow in favor of bright colors.

Answer 35

natural selection against bright colors by predation and sexual selection in favor of bright colors.

Question 36

Often, antlers are used for fighting between males, to win territory and mates. But the antlers of the Irish Elk were so massive that they would have made fighting difficult. Instead they may be due to _________, from females who preferred males with the largest antlers.

parental investment
intersexual selection
intrasexual selection
oscillating selection

Answer 36

intersexual selection

Question 37

Natural selection for a certain phenotype will affect the _________.

allele frequency of an individual
genotype of an individual
genotype of a population
allele frequency of a population

Answer 37

allele frequency of a population

Question 38

_________ would keep a population in Hardy-Weinberg equilibrium.

Gene flow
Selection
Random mating
Genetic drift

Answer 38

Random mating

Question 39

Hardy-Weinberg pointed out that the original proportions of the genotypes in a population would remain constant from generation to generation if certain assumptions are met. Which one of the following is NOT a Hardy-Weinberg condition?

No selection occurs.
Random mating occurs.
No gene flow occurs.
No polymorphic loci exist in the population.

Answer 39

No polymorphic loci exist in the population.

Question 40

Antigens on red blood cells are hereditary traits that allow blood to be typed in different ways. One system is based on a gene with two alleles, M and N. If the frequency of the M allele in a population is 0.4, then according to the Hardy-Weinberg rule, the expected frequency of the heterozygous MN genotype is _________.

0.24
0.48
0.6
0.16

Answer 40

0.48

Question 41

The preservation of genes that increase the likelihood of survival and reproduction of some individuals within a population is called the process of

natural selection.
genetic drift.
creation of new species.
increasing evolutionary resistance.

Answer 41

natural selection.

Question 42

In the Hardy-Weinberg equation, p and q are _________.

allele frequencies
measures of fitness
genotype frequencies
phenotype frequencies

Answer 42

allele frequencies

Question 43

During a drought on the Galapagos islands, finches with larger beaks were able to crack the large tough seeds produced by plants that survived the dry conditions. This is an example of _________.

a founder effect
disruptive selection
directional selection
genetic drift

Answer 43

directional selection

Question 44

Ear size is a variable trait in a certain mouse species. A few mice homozygous for the large-ear allele happened to arrive on an island that already contained a population of small-eared mice. This is an example of _________

genetic drift.
natural selection.
a bottleneck effect.
gene flow.

Answer 44

gene flow.

Question 45

A population of lizards lives in a rocky area next to a desert. Some lizards are light-colored and blend into the sand. Others are dark and blend into the rocks. What may happen to this population of lizards over time?

They may remain one species as a result of disruptive selection.
They may evolve into two separate species as a result of disruptive selection.
They may remain one species as a result of stabilizing selection.
They may remain one species as a result of directional selection.

Answer 45

They may evolve into two separate species as a result of disruptive selection.

Question 46

A restriction in genetic variability caused by a drastic reduction in population size is called a

founder effect.
Hardy-Weinberg effect.
bottleneck effect.
polymorphic effect.

Answer 46

bottleneck effect.

Question 47

The California populations of the Northern elephant seal are descendants from a very small population of seals that was overhunted in the 1890s. Heterozygosity in this population would be expected to be _________due to _________.

low; the Hardy-Weinberg effect
great; a bottleneck effect
low; a bottleneck effect
great; disruptive selection

Answer 47

low; a bottleneck effect

Question 48

The midrange of an array of phenotypes is favored in _________.

gene flow
disruptive selection
stabilizing selection
directional selection

Answer 48

stabilizing selection

Question 49

A population of flowers is in Hardy-Weinberg equilibrium with an allele frequency for white flowers (w) of 40%. What percentage of the flowers will have the colored or dominant phenotype?

60%
88%
84%
16%

Answer 49

84%

Question 50

Some flowering plants cannot self-pollinate which increases their tendency to mate with phenotypically different mates, a process called disassortative mating. What effect would this have on a population, compared to expectations based on the Hardy-Weinberg principle?

The population would remain in Hardy-Weinberg equilibrium.
An increase in heterozygotes would be observed.
A decrease in heterozygotes would be observed.
No change homozygotes or heterozygotes would be observe

Answer 50

An increase in heterozygotes would be observed.

Question 51

Which factor does NOT result in gene flow?

Hybridization between neighboring populations
Gametes dispersed by ocean currents
Disassortative mating within a population
Wind-blown pollen

Answer 51

Disassortative mating within a population

Question 52

A human autosomal recessive trait appears in 1 in 100 births. What percent of people are homozygous dominant for this gene?

90%
18%
1%
81%

Answer 52

81%

Question 53

Female cardinals select male mates in part based on their bright red color. What effect would this have on a cardinal population?

The frequency of red alleles would be less than those predicted by Hardy-Weinberg equilibrium.
The frequency of red alleles would be greater than those predicted by Hardy-Weinberg equilibrium.
The frequency of red alleles would be equal to those predicted by Hardy-Weinberg equilibrium.
The red allele frequencies would remain unchanged because of equilibrium.

Answer 53

The frequency of red alleles would be greater than those predicted by Hardy-Weinberg equilibrium.

Question 54

The observation that many Native Americans have type O blood is best explained by _________

founder effect.
gene flow.
assortative mating.
frequent mutations.

Answer 54

founder effect.

Question 55

The presence of the disease sickle cell anemia illustrates that natural selection does not always eliminate _________ alleles.

epistatic
dominant
polymorphic
recessive

Answer 55

recessive

Question 56

As a mechanism of evolution, natural selection acts on variants within populations and ultimately leads to different species. This was proposed by

Aristotle
Mendel.
Darwin.
Malthus.

Answer 56

Darwin.

Question 57

In the early ancestors of the modern giraffe, longer necks allowed animals to reach higher tree branches as food. This would lead to _________in the ancestral giraffe population.

directional selection
genetic drift
disruptive selection
stabilizing selection

Answer 57

directional selection