Practice Questions for Ap Chapters 22,23,24

Practice problems

PRACTICE QUESTIONS FOR AP CHAPTERS 22,23,24

Researchers examining a particular gene in a fruit fly population discovered that the gene can have either of two slightly different sequences, designated A1 and A2. Further tests showed that 70% of the gametes produced in the population contained the A1 sequence. If the population is at Hardy-Weinberg equilibrium, what proportion of the flies carries both A1 and A2?

A) / 0.7
B) / 0.49
C) / 0.21
D) / 0.42
E) / 0.09

ANS: D

Explanation: BACKGROUND: p + q = 1 and p2 + 2pq + q2 =1

.7 of gametes have an A1 allele ---this is “p”

.3 of the gametes must have the other allele ( a2) ----remember p + q = 1

Carriers are ( A1 A2) –this is 2pq

So now calculate 2pq to represent homozygous genotypes (2pq)

2 (.7 * .3 ) = .42

At a locus with a dominant and a recessive allele in Hardy-Weinberg equilibrium, 16% of the individuals are homozygous for the recessive allele. What is the frequency of the dominant allele in the population?

A) / 0.84
B) / 0.36
C) / 0.6
D) / 0.4
E) / 0.48

ANS: C

.16 = q2

Square root of .16 = .4 (this is q)

1-q=p so 1- .4 = .6; p (dominant allele frequency, equals .6)

4) The average length of jackrabbit ears decreases gradually with increasing latitude. This variation is an example of

A) / directional selection.
B) / discrete variation.
C) / polymorphism.
D) / genetic drift.
E) / disruptive selection.

ANS: A

Which of the following is a polymorphic trait in humans?

A) / variation in height
B) / variation in intelligence
C) / free versus attached earlobes
D) / variation in the number of fingers
E) / variation in fingerprints

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.7. What is the percentage of the population that is homozygous for this allele?

A) / 3
B) / 9
C) / 30
D) / 42
E) / 49

ANS: E

Explanation: a is the recessive allele and represents q

If the frequency of q is .7, then the frequency of q2 (homozygous recessive genotypes) is .7 * .7=.49

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.7. What is the percentage of the population that is heterozygous for this allele?

A) / 3
B) / 9
C) / 21
D) / 30
E) / 42

ANS: E

In a hypothetical population of 1,000 people, tests of blood-type genes show that 160 have the genotype AA, 480 have the genotype AB, and 360 have the genotype BB.

17) What is the frequency of the A allele?

A) / 0.001
B) / 0.002
C) / 0.100
D) / 0.400
E) / 0.600

ANS: D

In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple flowers and 64 white flowers. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?

A) / 0.36
B) / 0.60
C) / 0.64
D) / 0.75
E) / 0.80

ANS: E

Which factor is the most important in producing the variability that occurs in each generation of humans?

A) / mutation
B) / sexual recombination
C) / genetic drift
D) / nonrandom mating
E) / natural selection

ANS: B

If the frequency of a recessive gene in a population under genetic equilibrium is 40 percent, in the next generation the frequency of that gene would be

a. / 20 percent.
b. / 40 percent.
c. / 80 percent.
d. / dependent upon other factors, so it cannot be predicted but must instead be reevaluated each generation.

ANS: B

. If the frequency of expression of a recessive trait in a population is 16 percent, the frequency of the recessive allele would be what percent?

a. / 16
b. / 25
c. / 40
d. / 50
e. / 67

ANS: C

If the frequency of a recessive allele is 36 percent, the frequency of the dominant allele would be what percent?

a. / 5
b. / 8
c. / 25
d. / 48
e. / 64

ANS: E

Explanation: The frequency of the recessive and the frequency of the dominant alleles together must add up to 1.

. In the Hardy-Weinberg equation, the term q2 refers to the frequency of

a. / a recessive allele of a given locus.
b. / the homozygous recessive genotype at a given locus.
c. / recessive alleles in a population.
d. / heterozygotes in a population.

ANS: B

Male mallards have had emerald green head feathers and wings with metallic blue patches for hundreds of years, whereas female mallards have been drab brown-feathered ducks. This phenotypic situation suggests that mallards may be an example of

a. / directional selection.
b. / polyploidy.
c. / allopatric speciation.
d. / disruptive selection.
e. / sexual isolation.

ANS: D

In a certain bird species, clutch size (the number of eggs laid by a female in one breeding season) ranges from four to eight, and the most frequent clutch size is six. This phenomenon is an example of

a. / sexual selection.
b. / stabilizing selection.
c. / disruptive selection.
d. / directional selection.

ANS: B

Balanced polymorphism is a type of

a. / disruptive selection.
b. / sexual selection.
c. / directional selection.
d. / reproductive isolation.
e. / stabilizing selection.

ANS: E

The decline in the frequency of the sickle-cell anemia allele in the American population is the result of

a. / a lower mutation rate in the United States than in Africa.
b. / the advantage of both homozygous forms over the heterozygous form.
c. / the development of appropriate medical treatment in the United States.
d. / a decline in the occurrence of malaria in the United States.

ANS: D

. The persistence of the sickle-cell anemia allele in the African population is the result of

a. / a high rate of mutation of the normal allele to the sickle-cell anemia allele.
b. / the advantage of the heterozygous form over the homozygous forms.
c. / nonrandom mating.
d. / a decline in the occurrence of malaria in Africa.

The persistence of the sickle-cell anemia allele in the African population is the result of

ANS: B

. The HbS allele (sickle cell) occurs at a higher frequency in Africa than it does in the United States because

a. / it is a dominant allele in Africa and a recessive one in the United States.
b. / genetic recombination occurs at different rates in different human populations.
c. / natural selection favors heterozygotes in Africa but favors homozygous normal individuals in the United States.
d. / the African population is descended from a small group of individuals who possessed the allele at a high frequency.

ANS: C

The sharp reduction of the gene pool and the numbers of a population through a severe epidemic is an example of

a. / natural selection.
b. / genetic isolation.
c. / the bottleneck effect.
d. / the founder principle.
e. / all of these

ANS: C

If you sampled the genetic characteristics of a large population and found that of the 50 loci analyzed there was very little if any variation, the most likely explanation would be that

a. / a uniform environment selected for these alleles.
b. / there has been a lack of migration and the genetic equilibrium stabilized the population.
c. / strong selection pressures eliminated alternative alleles.
d. / a bottleneck effect may have occurred in the past to reduce the variability in the population.
e. / a combination of low mutation rates and differential sexual selection produced these results.

Choose the most appropriate answer for each.

a. / wrote Principles of Geology
b. / developed the theory of catastrophism
c. / believed that giraffes have long necks because their short-necked ancestors stretched their necks and passed this change on to their offspring
d. / was a naturalist who sailed on the Beagle and studied finches
e. / wrote Essay on the Principle of Population
f. / wrote Scala Naturae, early ideas of great Chain of Being
g. / believed in several centers of creation and the idea that species may have changed through time

1. Aristotle

2. Buffon

3. Cuvier

4. Darwin

5. Lamarck

6. Lyell

7. Malthus

1. ANS: F

2. ANS: G

3. ANS: B

4. ANS: D

5. ANS: C

6. ANS: A

7. ANS: E

Choose the most appropriate letter for each.

a. / a reference point that implies stability of gene frequencies through generations
b. / encompasses all of those actually or potentially interbreeding populations that are reproductively isolated from other such groups
c. / the genes of an entire population
d. / the frequency of homozygous dominants in a population
e. / the frequencies of dominant and recessive alleles in a population
f. / the frequency of heterozygotes in a population
g. / the frequency of homozygous recessives in a population
h. / HbA and HbS in regions where malaria is found
i. / pesticide-resistant pests

Which of the following habitats is most likely to be rich in fossils?

a. / eroding hillsides
b. / deserts
c. / polar ice caps
d. / bed of former shallow sea
e. / rocky plateau

ANS: D

When DDT was first introduced, insects were very susceptible to it. The development of resistance to DDT by insects was the result of

a. / special creation.
b. / natural selection of forms that expressed genes for resistance.
c. / the high biotic potential of insects.
d. / a naturally occurring example of inheritance of acquired characteristics.
e. / Somatic cell mutation induced by DDT.

Use the information below to answer the following questions.

A researcher compared the nucleotide sequences of a homologous gene from five different species of mammals with the homologous human gene. The sequence homology between each species' version of the gene and the human gene is presented as a percentage of similarity.

Species / Percentage
Chimpanzee / 99.7
Orangutan / 98.6
Baboon / 97.2
Rhesus Monkey / 96.9
Rabbit / 93.7

What conclusion can be drawn validly from these data?

A) / Humans and other primates evolved from rabbits within the past 10 million years.
B) / Most of the genes of other organisms are paralogous to human genes, or with chimpanzee genes.
C) / Among the organisms listed, humans shared a common ancestor most recently with chimpanzees.
D) / Humans evolved from chimpanzees somewhere in Africa within the last 6 million years.
E) / Both B and C are correct.

ANS: C

The ostrich and the emu look very similar and live in similar habitats, however they are not very closely related. This is an example of

A) / divergent evolution.
B) / convergent evolution.
C) / exaptation.
D) / adaptive radiation.
E) / sympatric speciation.

Use the options below to answer the following questions. For each description of reproductive isolation, select the option that best describes it. Options may be used once, more than once, or not at all.

A. / gametic
B. / temporal
C. / behavioral
D. / habitat
E. / mechanical

two species of orchids with different floral anatomy

A) / A
B) / B
C) / C
D) / D
E) / E

ANS: E

two species of trout that breed in different seasons

A) / A
B) / B
C) / C
D) / D
E) / E

ANS: B

two species of meadowlarks with different mating songs

A) / A
B) / B
C) / C
D) / D
E) / E

ANS: C

two species of garter snakes live in the same region, but one lives in water and the other lives on land

A) / A
B) / B
C) / C
D) / D
E) / E

ANS: D

two species of pine shed their pollen at different times

A) / A
B) / B
C) / C
D) / D
E)

ANS: B