LS 7B

Question 1

How do most cancers arise?

A. from a single mutations arising simultaneously in a cluster of cells

B. from a series of mutations that arise in the descendants of a single somatic cell

C. from multiple mutations arising simultaneously in a single cell

D. from mutations arising in a single cell that are then transmitted to other cells in the body

Answer 1

B. from a series of mutations that arise in the descendants of a single somatic cell

Question 2

How do mutations arise?

A. Mutations in cancer cells arise because they need to divide faster.

B. Mutations arise in a specific sequence where a mutation in one gene directly leads to a mutation in a specific second gene.

C. Mutations arise randomly and independent of other mutations in the cell.

D. Mutations arise simultaneously, where whole sets of mutations occur in a single event.

Answer 2

C. Mutations arise randomly and independent of other mutations in the cell.

Question 3

What effect does each successive mutation have on the colon cells in the example?

A. It causes them to leave the colon and spread to other tissues.

B. It causes them to divide more rapidly than normal cells.

C. It causes them to become non-colon cells.

D. In causes them to become larger and expand in the colon.

Answer 3

B. It causes them to divide more rapidly than normal cells.

Question 4

When p53 becomes mutant in cells already mutant for APC and Ras, what occurs?

A. These cells survive despite DNA damage and divide extremely rapidly.

B. These cells die.

C. These cells remain benign.

D. These cells expand their chromosome number to 53.

Answer 4

A. These cells survive despite DNA damage and divide extremely rapidly.

Question 5

According to Figure 14.2, the average number of new mutations that occur across an entire human genome in one generation is approximately _____ times higher than in nematodes.

A. 100

B. 1000

C. 10

D. 10,000

E. 2

Answer 5

A. 100

Question 6

The number of new mutations in organisms following a round of genome replication:

A. generally decreases with larger genomes.

B. generally increases with larger genomes.

C. None of the answer options is correct.

D. is highest in bacteria.

E. is similar, independent of genome size.

Answer 6

B. generally increases with larger genomes.

Question 7

Sites in the genome that are more susceptible to mutations than others are called:

A. risk factors.

B. genes.

C. mutation spots.

D. hotspots.

E. noncoding DNA.

Answer 7

D. hotspots.

Question 8

_____ mutations are important to the evolutionary process; most cancers result from _____ mutations.

A. Somatic; germ-line

B. Germ-line; heritable

C. Somatic; heritable

D. Point; germ-line

E. Germ-line; somatic

Answer 8

E. Germ-line; somatic

Question 9

Which of the following statements concerning cancer and mutations is CORRECT?

A. Cancer can only occur with a mutation in a somatic cell.

B. Usually, multiple mutations are required in different genes to cause cancer.

C. Usually, a single mutation is all that is required to cause cancer.

D. Cancer can only occur with a mutation in a germ cell.

E. None of the other answer options is correct.

Answer 9

B. Usually, multiple mutations are required in different genes to cause cancer.

Question 10

The definition of mutation is “any heritable change in the genetic material.” The qualifier “heritable” is necessary because:

A. most changes in the genetic material are harmful to the organism.

B. changes in the genetic material occur without regard to the needs of the organism.

C. changes in the genetic material occur at random along the genome.

D. most changes in the genetic material are repaired soon after they occur.

Answer 10

D. most changes in the genetic material are repaired soon after they occur.

Question 11

Prophase of meiosis I has some important differences from prophase of mitosis. These differences include: ___________ pair, and _________ occurs.

A. chromatids; condensation

B. chromosomes; separation

C. homologous chromosomes; crossing over ,

D. homologous chromatids; separation

Answer 11

C. homologous chromosomes; crossing over

Question 12

During meiosis crossing over takes place between:

A. any two chromatids.

B. sister chromatids.

C. non-sister chromatids.

D. nonhomologous chromosomes.

E. nonhomologous chromatids.

Answer 12

C. non-sister chromatids.

Question 13

In this partial image of anaphase I of meiosis, most of a chromosome is shaded dark, whereas a portion of what is in the circle is shaded light. Which of the following statements best explains the meaning of this shading?

A. The dark and light indicate homologous chromosomes.

B. The light part came from the homolog by crossing over.

C. The light part is a mixture of genes from both parental types.

D. The light and dark parts are different genes.

Answer 13

B. The light part came from the homolog by crossing over.

Question 14

In the image below, let the light shade indicate maternally derived chromosomal material and the dark shade indicate paternally derived material. Which circle is likely to contain both paternal and maternal gene variants (alleles)?

A. circle a

B. circle b

C. circle c

D. circle d

Answer 14

B. circle b

Question 15

In the figure below, which box encloses two copies of the same gene variants (alleles) from only one of the parents?

A. box a

B. box b

C. box c

D. box d

Answer 15

C. box c

Question 16

In the figure below, which box encloses gene variants (alleles) of the same genes from both parents?

A. box a

B. box b

C. box c

D. box d

Answer 16

B. box b

Question 17

In the figure below, which box contains only single gene copies from one of the parents?

A. box a

B. box b

C. box c

D. box d

Answer 17

A. box a

Question 18

In the figure below, which box contains some gene variants (alleles) from one parent and some from the other, but not variant alleles from the same gene?

A. box a

B. box b

C. box c

D. box d

Answer 18

D. box d

Question 19

Which of the following is NOT true about gametes?

A. They are genetically identical to other gametes formed during meiosis.

B. They fuse to form a new organism during fertilization.

C. They have half as many chromosomes as a somatic cell of the same individual.

D. They are formed by meiotic cell division.

E. They are called eggs and sperm in animals.

Answer 19

A. They are genetically identical to other gametes formed during meiosis.

Question 20

Which of the following is NOT a characteristic of meiotic cell division?

A. Cell division results in the production of gametes.

B. Daughter cells are genetically identical.

C. Cell division requires two rounds of nuclear division.

D. Cell division results in the formation of four daughter cells.

Answer 20

B. Daughter cells are genetically identical.

Question 21

When do sister chromatids separate in meiosis?

A. anaphase I

B. metaphase II

C. telophase I

D. anaphase II

Answer 21

D. anaphase II

Question 22

Homologous chromosomes separate from each other in:

A. meiosis I.

B. mitosis.

C. They never separate from each other during any form of cell division.

D. meiosis II.

Answer 22

A. meiosis I.

Question 23

In a population of organisms with 4 alleles, how many homozygous genotypes are possible? How many heterozygous genotypes are possible?

A. 3; 4

B. 4; 3

C. 4; 4

D. 4; 6

E. 4; 10

Answer 23

D. 4; 6

Question 24

Consider a gene with four alleles A1, A2, A3, and A4. How many distinct heterozygous genotypes are possible?

A. 2

B. 3

C. 4

D. 5

E. 6

Answer 24

E. 6

Question 25

Gene A exists in five forms in the human population. Each form, or allele, has a different number of tandem repeats. The alleles are amplified with PCR and then run on a polyacrylamide gel for analysis, yielding the following banding pattern.

Which of the lanes in the gel below could represent the alleles found in one individual?

A. All 5 lanes are possible.

B. Lanes 2, 4, and 5 are possible.

C. Lanes 2, 3, 4, and 5 are possible.

D. Lanes 1, 2, 3, and 4 are possible.

Answer 25

B. Lanes 2, 4, and 5 are possible.

Instructional Guidance: This question emphasizes that each numerical variant is an allele and that each individual has a maximum of 2 possible alleles. This second point seems to be a common stumbling block for students. If used during in-class instruction instead of an exam, different lanes could be included or excluded. Then, the complete gel could be used on an exam question because students have been given this example previously. The question might be made a little easier by eliminating the homozygous genotype in lane 5 or using it as a point of discussion in class.

Question 26

In genetics, the dash symbol (–) is a “wild card” that stands for either the dominant allele or the recessive allele; for example, A– means the individual has either the genotype AA or Aa. Two genes that undergo independent assortment affect coat color in the house mouse. Each gene has two alleles, one of which is dominant for coat color. Genotypes of the form A– B– have a brownish color called agouti, those of the form A– bb are black, and those of the form aa B– and aa bb are albino (white). What ratio of agouti : black : white is expected from the cross Aa Bb × Aa Bb?

A. 10:3:3

B. 9:3:4

C. 12:3:1

D. 9:6:1

Answer 26

B. 9:3:4

Question 27

In genetics, the dash symbol (–) is a “wild card” that stands for either the dominant allele or the recessive allele; for example, A– means the individual has either the genotype AA or Aa. Two genes that undergo independent assortment affect flower color in sweet peas. Each gene as two alleles, one of which is dominant for flower color. Genotypes of the form A– B– have purple flowers, whereas those of the form A– bb, aa B–, and aa bb have white flowers. What ratio of purple : white is expected from the cross Aa Bb × Aa Bb?

A. 9:7

B. 10:6

C. 12:4

D. 13:3

E. 15:1

Answer 27

A. 9:7

Instructional Guidance: This type of epistasis is known as “duplicate recessive epistasis.”

Question 28

A pea plant is heterozygous (Aa) for seed color and heterozygous (Bb) for seed shape. According to Mendel’s principle of independent assortment: (Select all that apply.)

A. each gamete will contain either a seed-color allele or a seed-shape allele, but not both.

B. a gamete that contains dominant allele for seed color must also contain the dominant allele for seed shape.

C. a gamete that contains dominant allele for seed color must also contain the recessive allele for seed shape.

D. a gamete that contains the dominant allele for seed color is equally likely to contain the dominant or the recessive allele for seed shape.

E. possible gamete genotypes are AB or ab; each is equally likely to occur.

Answer 28

D. a gamete that contains the dominant allele for seed color is equally likely to contain the dominant or the recessive allele for seed shape.

E. possible gamete genotypes are AB or ab; each is equally likely to occur.

Question 29

With independent assortment, the ratio of genotypes in the F2 generation of a cross between true-breeding strains (AA bb × aa BB) can be described as 1:2:1:2:4:2:1:2:1. To what genotype does the “4” in the ratio refer?

A. AA Bb

B. Aa BB

C. Aa Bb

D. None of the answer options is correct.

Answer 29

C. Aa Bb

Question 30

Consider a gene with n alleles A1, A2, …, An. How many distinct genotypes are possible, taking into account both homozygous and heterozygous genotypes?

A. n2

B. n2/2

C. n(n –1)

D. n(n – 1)/2

E. n(n + 1)/2

Answer 30

E. n(n + 1)/2

Question 31

Assuming that the trait represented by the filled symbols below is a rare inherited trait with complete penetrance due to a single gene with alleles A and a, what mode of inheritance does the pedigree suggest?

A. dominant

B. recessive

Answer 31

B. recessive

Question 32

In the pedigree above, what can you say about the likely genotypes of individuals A and B?

A. both are AA

B. one is AA and the other is Aa

C. both are Aa

D. It is not possible to determine this for certain from the information provided.

Answer 32

C. both are Aa

Question 33

You are given two populations of true-breeding tomato plants with two simple dominant/recessive traits that sort independently. Using the multiplication rule, how many different phenotypic combinations would you expect to see in the F2 generation? In what phenotypic ratio?

A. two, 3:1

B. three, 9:6:1

C. four, 9:3:3:1

Answer 33

C. four, 9:3:3:1

Question 34

Imagine that a rancher has a herd of cattle with brown hides and short horns. All of his cattle are also relatively short in stature. If all of these traits were true-breeding, what could you say about the progeny of these cattle?

A. It is impossible to determine the traits of such progeny―they will likely demonstrate different hide colors, horn lengths, and heights.

B. The progeny of these cattle will have short horns, but a variety of hide colors and heights.

C. The progeny of these cattle will have brown, black, white, and spotted hides.

D. Because the cattle are true-breeding, the progeny of this herd will all be sterile.

E. The progeny of these cattle will be short in stature and have brown hides and short horns.

Answer 34

E. The progeny of these cattle will be short in stature and have brown hides and short horns.

Question 35

In humans, ability to roll the tongue (R) is dominant to being unable to roll (r). Having freckles (F) is dominant to having no freckles (f). A freckled tongue-roller could have which of the following genotypes?

A. RRFF

B. RrFf

C. rrFF

D. RRFF and RrFf only

E. All of these choices are correct.

Answer 35

D. RRFF and RrFf only

Question 36

In a diploid individual, one chromosome carries A and B genes, and the homologous chromosome carries different forms (alleles) of these same genes, a and b. If there is a single crossover between these two genes involving non-sister chromatids during metaphase I of meiosis, the resulting four gametes are:

A. AB, AB, ab, ab.

B. AB, ab, AB, ab.

C. AaBb, AaBb, AaBb, AaBb.

D. AB, Ab, aB, ab.

E. Ab, Ab, aB, aB.

Answer 36

D. AB, Ab, aB, ab.

Question 37

Flower color in snapdragons is due to a gene with incomplete dominance: CRCR plants have red flowers, CRCW have pink flowers, and CWCW plants have white flowers. Which cross is expected to yield progeny that all have pink flowers?

A. CRCR × CRCW

B. CRCR × CWCW

C. CRCW × CRCW

D. CRCW ×CWCW

E. CWCW × CWCW

Answer 37

B. CRCR × CWCW

Question 38

In the F2 generation of a homozygous round (AA) × homozygous wrinkled (aa) cross in peas, three seeds are chosen at random. What is the probability that two seeds are round and the other is wrinkled?

A. (1/4)^3

B. 3(1/4)(3/4)^2

C. 3(1/4)^2(3/4)

D. (3/4)^3

Answer 38

B. 3(1/4)(3/4)^2

Question 39

Consider a gene with four alleles A1, A2, A3, and A4. If the cross A1A2 × A3A4 yields two offspring, what is the probability that both of them have the same genotype?

A. 1/8

B. 1/4

C. 1/3

D. 1/2

E. 3/4

Answer 39

B. 1/4

Question 40

In genetics, the dash symbol (–) is a “wild card” that stands for either the dominant allele or the recessive allele; for example, W– means the individual has either the genotype WW or Ww. In summer squash, genotypes W– G– and W– gg are white, ww G– are yellow, and ww gg are green. W and G show independent assortment. What is the ratio of white : yellow : green among progeny of the cross Ww Gg × Ww Gg?

A. 12:3:1

B. 9:3:1

C. 10:3:3

D. 9:6:1

E. None of the answer options is correct.

Answer 40

A. 12:3:1

Question 41

If you crossed two heterozygous yellow-seed pea plants (genotypes Aa), the relative frequency of:

A. the a allele in each parent’s gametes would be 1/2.

B. the A allele in each parent’s gametes would be 1/2.

C. green-seed plants (genotype aa) would be 1/4.

D. homozygous yellow-seed plants (genotype AA) would be 1/4.

E. All of these choices are correct.

Answer 41

E. All of these choices are correct.

Question 42

Among the progeny of a heterozygous round (Aa) × homozygous wrinkled (aa) testcross, three seeds are chosen at random. What is the probability that all three seeds are round?

A. (1/2)3

B. 2(1/2)3

C. 3(1/2)3

D. 4(1/2)3

Answer 42

A. (1/2)^3

Question 43

According to Figure 14.2, the average number of new mutations that occur across an entire human genome in one generation is approximately _____ times higher than in nematodes.

A. 2

B. 10

C. 100

D. 1000

E. 10,000

Answer 43

C. 100

Question 44

Consider a gene with four alleles A1, A2, A3, and A4. In the cross A1A2 × A3A3, how many offspring genotypes are possible?

A. 2

B. 3

C. 4

E. 5

F. 6

Answer 44

A. 2

Question 45

A true-breeding black rabbit is crossed with a true-breeding white rabbit to produce an F1 generation of 15 individuals. If the black color trait is dominant, which of the following represents the expected phenotype of an F1 generation cross?

A. 15 black rabbits, 0 white rabbits, 0 grey rabbits

B. 5 black rabbits, 5 white rabbits, 6 grey rabbits

C. 0 black rabbits, 0 white rabbits, 15 grey rabbits

D. 5 black rabbits, 3 white rabbits, 7 grey rabbits

E. 0 black rabbits, 15 white rabbits, 0 grey rabbits

Answer 45

A. 15 black rabbits, 0 white rabbits, 0 grey rabbits

Question 46

During meiosis in the female, sex chromosomes segregate to produce two types of eggs: X-bearing eggs and Y-bearing eggs.

A. True

B. False

Answer 46

B. False

Question 47

All organisms have either an X or Y chromosome, as these chromosomes are solely responsible for determining the sex of an individual. Mendel’s failure to identify X and Y chromosomes in his pea plants invalidated a portion of the data he collected.

A. False

B. True

Answer 47

A. False

Question 48

Homologous chromosomes usually have the same arrangement of genes along their length.

A. True

B. False

Answer 48

A. True

Question 49

Genes located along the X chromosome:

A. have a full set of complementary alleles in the Y chromosome.

B. are contributed solely by the female parent.

C. are called X-linked genes.

D. are always recessive to genes located in the Y chromosome.

Answer 49

C. are called X-linked genes.

Question 50

Which of the following is true of a cross involving a sex-linked gene but not of a cross involving an autosomal gene?

A. The phenotype outcomes of female offspring compared to males can be different.

B. A Punnett square cannot be utilized for illustrating the possible outcomes of a cross involving a sex-linked gene.

C. Only autosomal genes observe the law of segregation.

D. Both parents have two copies of a sex-linked gene.

E. Recombination or crossing over cannot take place between sex chromosomes.

Answer 50

A. The phenotype outcomes of female offspring compared to males can be different.

Question 51

Review the pedigree shown in Figure 17.7 and choose the most accurate statement about the inheritance of an X-linked recessive mutation.

A. The brothers of affected males are always affected.

B. The offspring of an affected male are usually affected.

C. For rare X-linked traits, most of the affected individuals are males.

D. The sons of the sisters of affected males will always be affected.

E. Daughters of affected males are always affected.

Answer 51

C. For rare X-linked traits, most of the affected individuals are males.

Question 52

Which of the following is a possible human genotype that could result from nondisjunction of the sex chromosomes in one of the parental gametes?

A. All of these choices are correct.

B. XO

C. XYY

D. XXX

E. XXY

Answer 52

A. All of these choices are correct.

Question 53

Sometimes homologous chromosomes fail to separate normally during meiosis I, a process called:

A. nontransferrance.

B. chromosome separation.

C. nondisjunction.

D. conjugation.

E. unijunction.

Answer 53

C. nondisjunction.

Question 54

A heterozygous female harboring one mutant allele for hemophilia is called a(n) _____ for that trait.

A. messenger

B. homozygote

C. unaffected female

D. carrier

E. harborer

Answer 54

D. carrier

Question 55

For most genes on the human X chromosome, what percent of XY males with a mutant allele on the X chromosome will express the mutant phenotype?

A. 0%

B. 25%

C. 50%

D. 100%

E. There is insufficient data to predict.

Answer 55

D. 100%

Question 56

In humans, fruit flies, and many other organisms, most of the genes on the X chromosome are not found on the Y chromosome.

A. true

B. false

Answer 56

A. true

Question 57

If an XY male carries a mutation on his X chromosome, _______________BLANK will receive the mutant X.

A. all of his sons

B. all of his daughters

C. all his sons and daughters

D. half his sons and half his daughters

Answer 57

B. all of his daughters

Question 58

A normal female who carries a recessive X-linked allele for hemophilia will pass it on to:

A. all of her daughters.

B. half of her daughters.

C. all of her sons.

D. half of her sons.

E. half of both her sons and daughters.

Answer 58

E. half of both her sons and daughters.

Question 59

Color blindness is a recessive X-linked trait in humans. In a family where the mother is color-blind and the father is normal, the probability of their having a color-blind son is:

A. 0.

B. 1.

C. 1/4.

D. 1/2.

E. 1/16.

Answer 59

B. 1.

Question 60

Color blindness is a recessive X-linked trait in humans. In a family where the mother is heterozygous for color blindness and the father is color-blind, the probability of their having a color-blind daughter is:

A. 0.

B. 1.

C. 1/4.

D. 1/2.

E. 1/16.

Answer 60

D. 1/2.

Question 61

The genotype of a fetus can be screened for SNPs associated with some diseases.

A. True

B. False

Answer 61

A. True

Question 62

Mutations that destroy or create a cleavage site for a restriction enzyme are the source of:

A. restriction fragment length polymorphisms.

B. copy-number variants.

C. single-nucleotide polymorphisms.

D. variable number tandem repeats.

Answer 62

A. restriction fragment length polymorphisms.

Question 63

After doing PCR on the same region between two individuals, you notice that each person’s DNA yielded pieces of different sizes. Which of the following is the MOST likely explanation?

A. A mistake was made during gel electrophoresis.

B. A mistake was made during the PCR.

C. This is an example of VNTRs.

D. This is an example of RFLPs.

E. None of the answer options is correct.

Answer 63

C. This is an example of VNTRs.

Question 64

An individual is heterozygous for two linked genes, but whether its genotype is A B/a b or A b/a B is not known. The individual is crossed with an a b/a b individual, and among the progeny are the following:

16 A B/a b
54 A b/a b
46 a B/a b
24 a b/a b

These results imply that the genotype of the doubly heterozygous parent was A B/a b.

A. True

B. False

Answer 64

B. False

Instructional Guidance: The most frequent classes of gametes are the nonrecombinant (parental) types and therefore tell you that parental genotype.

Question 65

X-linked genes show crisscross inheritance because males:

A. get their Y chromosome from their father.

B. get their X chromosome from their mother.

C. transmit their Y chromosome to their sons.

D. transmit their X chromosome to their daughters.

E. get their Y chromosomes from their father and transmit their Y chromosomes to their sons.

F. get their X chromosomes from their mother and transmit their X chromosomes to their daughters.

Answer 65

F. get their X chromosomes from their mother and transmit their X chromosomes to their daughters.

Question 66

Suppose that certain genes related to the eye, ear, nose, and throat are present in two autosomes, and each of these genes has multiple alleles. The eye and ear genes have a recombination frequency of 25%, and the nose and throat genes have a recombination frequency of 35%. As a genetic counselor, you are examining these genes in a couple who are interested in having children soon. Simplified illustrations of the mother’s and father’s genotypes are below.

If the couple’s potential child inherits the eye7 allele from the mom, what is the chance of the child also inheriting the eye8 allele from the father?

A. 100%

B. 75%

C. 50%

D. 25%

E. 0%

Answer 66

E. 0%

Question 67

Suppose that certain genes related to the eye, ear, nose, and throat are present in two autosomes, and each of these genes has multiple alleles. The eye and ear genes have a recombination frequency of 25%, and the nose and throat genes have a recombination frequency of 35%. As a genetic counselor, you are examining these genes in a couple who are interested in having children soon. Simplified illustrations of the mother’s and father’s genotypes are below.

What proportion of the couple’s offspring will be eye7 eye7/nose3 nose3?

A. 1/4

B. 1/2

C. 1/8

D. 1/16

E. 1/32

Answer 67

D. 1/16

Question 68

Suppose that certain genes related to the eye, ear, nose, and throat are present in two autosomes, and each of these genes has multiple alleles. The eye and ear genes have a recombination frequency of 25%, and the nose and throat genes have a recombination frequency of 35%. As a genetic counselor, you are examining these genes in a couple who are interested in having children soon. Simplified illustrations of the mother’s and father’s genotypes are below.

Assuming equal frequencies of recombination in females and males, which combination would be more common in offspring?

A. nose3 throat1 in one chromosome, nose3 throat1 in the other chromosome

B. nose3 throat1 in one chromosome, nose6 throat2 in the other chromosome

C. nose6 throat2 in one chromosome, nose6 throat2 in the other chromosome

D. None. All possible combinations would be equally represented in offspring.

Answer 68

D. None. All possible combinations would be equally represented in offspring.

Question 69

Suppose that certain genes related to the eye, ear, nose, and throat are present in two autosomes, and each of these genes has multiple alleles. The eye and ear genes have a recombination frequency of 25%, and the nose and throat genes have a recombination frequency of 35%. As a genetic counselor, you are examining these genes in a couple who are interested in having children soon. Simplified illustrations of the mother’s and father’s genotypes are below.

What proportion of the couple’s offspring will inherit eye7 ear4 from the mother?

A. 100%

B. 75%

C. 37.5%

D. 25%

E. 12.5%

Answer 69

C. 37.5%

Question 70

The pedigree shown here pertains to a trait due to a rare, X-linked recessive mutation.

Individual 1 has an affected father, but the genotypes and phenotypes of individuals 1–4 are unknown. What is the probability that individual 1 is heterozygous? What is the probability that individual 3 is heterozygous? What is the probability that individual 4 is affected?

A. 1/2; 1/4; 1/4

B. 1/2; 1/4; 1/2

C. 1; 1/4; 1/2

D. 1; 1/2; 1/4

E. 1; 1/2; 1/2

Answer 70

E. 1; 1/2; 1/2

Question 71

An individual who is heterozygous for two linked genes (with alleles A, a and B, b) is crossed with an a b/a b individual, and among the progeny are the following:

14 A B/a b
36 A b/a b
34 a B/a b
16 a b/a b

What is the frequency of recombination?

A. 0.30

B. 0.35

C. 0.40

D. 0.60

E. 0.70

Answer 71

A. 0.30

Question 72

Red-green color blindness is due to a mutant gene in the X chromosome. An XX female with normal color vision and an XY male with normal color vision have a child with karyotype XXY who is color blind. The likely explanation is that the:

A. father was heterozygous for the color-blindness mutation.

B. mother was heterozygous for the color-blind mutation.

C. father had CNV of the color-blind mutation.

D. mother had CNV of the color-blind mutation.

E. None of the other answer options is correct.

Answer 72

B. mother was heterozygous for the color-blind mutation.

Question 73

Considering an X-linked dominant trait, if an unaffected woman and an affected man decide to have children, which of the following statements is TRUE about the possibilities for their children?

A. Their sons are expected be heterozygous for the associated gene.

B. Their daughters are expected be heterozygous for the associated gene.

C. All their children, whether male or female, are expected to show the dominant trait.

D. All of their sons are expected to show the dominant trait.

E. Their daughters are not expected to show the dominant trait.

Answer 73

B. Their daughters are expected be heterozygous for the associated gene.

Question 74

Given equal probabilities of the birth of a boy or girl, what is the probability that a group of four siblings includes all boys? All girls? All boys or all girls?

A. 1/8; 1/16; 3/8

B. 1/16; 1/8; 3/8

C. 1/16; 1/16; 1/64

D. 1/16; 1/16; 1/8

Answer 74

D. 1/16; 1/16; 1/8

Question 75

The pedigree shown here pertains to a trait due to a rare, X-linked recessive mutation.

Individual 1 has an affected grandfather, but the genotypes and phenotypes of individuals 1–4 are unknown. What is the probability that individual 1 is heterozygous? What is the probability that individual 3 is heterozygous? What is the probability that individual 4 is affected?

A. 1; 1/4; 1/4

B. 1; 1/2; 1/2

C. 1/2; 1/4; 1/2

D. 1/2; 1/2; 1/2

E. 1/2; 1/4; 1/4

Answer 75

E. 1/2; 1/4; 1/4

Question 76

Hemophilia is a sex-linked recessive trait in humans. If a carrier female (heterozygous for the trait) mated with a nonaffected male, what would be the expected outcome(s)?

A. None of the offspring would have hemophilia.

B. None of the daughters would have hemophilia.

C. Half the daughters would have hemophilia.

D. Half the sons would have hemophilia.

E. None of the daughters would have hemophilia, and half of the sons would have hemophilia.

Answer 76

E. None of the daughters would have hemophilia, and half of the sons would have hemophilia.

Question 77

An individual that is heterozygous for two linked genes has the genotype A b/a B, which means that the A and b alleles are in one chromosome and the a and B alleles in the homologous chromosome. Among the products of meiosis listed below, which are the recombinant types? (Select all that apply.)

A. A B

B. A b

C. a B

D. a b

Answer 77

A. A B

D. a b

Question 78

What is an SNP?

A. a single nucleotide polymorphism

B. a location where individual alleles differ by one base pair

C. a genetic difference that can occur between different individuals

D. All of these choices are correct.

Answer 78

D. All of these choices are correct.

Question 79

Which of the following is not part of a microarray used to detect SNPs?

A. short DNA sequences attached to a glass slide

B. oligonucleotides that match the sequence of a known SNP site in the genome

C. mRNAs that are expressed from a specific gene

D. short DNA sequences synthesized with a specific sequence

E. oligonucleotides that differ in sequence only at the SNP itself and are positioned at different locations on a glass slide

Answer 79

C. mRNAs that are expressed from a specific gene

Question 80

Which of the following is not part of the process of using a microarray to detect SNPs in an individual’s DNA?

A. DNA from the individual is isolated from his or her cells.

B. Sequences from the region containing the SNP are amplified.

C. Amplified DNA is labeled with a fluorescent dye.

D. Proteins from the gene are allowed to stick to the microarray.

E. DNA is hybridized to the oligonucleotides to allow exact base pairing.

Answer 80

D. Proteins from the gene are allowed to stick to the microarray.

Question 81

How are SNP alleles in an individual detected using a microarray?

A. The DNA from the individual is sequenced using dideoxy sequencing.

B. The location on the microarray of the hybridizing DNA is visualized using a microscope.

C. DNA primers on each side of the SNP are hybridized for PCR.

Answer 81

B. The location on the microarray of the hybridizing DNA is visualized using a microscope.

Question 82

How will SNP microarray results differ in an analysis of DNA from an individual who is homozygous for one allele compared with an individual who is heterozygous for both alleles?

A. The strength of the fluorescent glow will be stronger in the analysis of DNA from the homozygous individual.

B. The fluorescent signal will be detected for both A−T and G−C base pairs in analysis of DNA from the heterozygous individual, but for only one of these base pairs in DNA from homozygotes.

C. DNA from heterozygous individuals will not be hybridized to the microarray, but base-pair matching hybridization will occur using DNA from heterozygotes.

Answer 82

B. The fluorescent signal will be detected for both A−T and G−C base pairs in analysis of DNA from the heterozygous individual, but for only one of these base pairs in DNA from homozygotes.

Question 83

How many SNPs can be detected using a single microarray?

A. 1

B. 2

C. 46

D. millions

Answer 83

D. millions

Question 84

Much of the genetic variation seen in the human population is neutral.

A. False

B. True

Answer 84

B. True

Question 85

A newly arisen point mutation always creates an SNP.

A. True

B. False

Answer 85

B. False

Question 86

For an SNP with three alleles, how many different diploid genotypes are possible?

A. 3

B. 4

C. 6

D. 7

E. 5

Answer 86

C. 6

Question 87

A new gene is discovered that dramatically aids in the digestion of fish. You hypothesize that populations with a history of being near the shoreline would have more copies of this gene than populations found farther inland. How would you classify this genetic difference?

A. SNP

B. RFLP

C. CNV

D. VNTR

E. None of the answer options is correct

Answer 87

C. CNV

Question 88

Saying that a SNP is associated with a disease means that if you possess that particular SNP, you will end up with that disease.

A. True

B. False

Answer 88

B. False

Question 89

SNPs arise from:

A. translocations.

B. inversions.

C. point mutations.

D. deletions.

E. duplications.

Answer 89

C. point mutations.

Question 90

Consider a normal human cell in which one chromosome undergoes nondisjunction in mitosis. What chromosome numbers would be found in the daughter cells?

A. 46 and 47

B. None of the answer options is correct.

C. 45 and 46

D. 46 and 46

E. 45 and 47

Answer 90

E. 45 and 47

Question 91

First division nondisjunction will only yield gametes with an extra chromosome, whereas second division nondisjunction will only yield gametes missing a chromosome.

A. True

B. False

Answer 91

B. False

Question 92

The failure of a pair of chromosomes to separate during anaphase is referred to as:

A. nondisjunction.

B. translocation.

C. trisomy.

D. disjunction.

E. inversion.

Answer 92

A. nondisjunction.

Question 93

What is one reason a woman with the genotype XXX are not phenotypically different from an XX female?

A. The extra X chromosome only becomes active in nonreproductive areas of the body.

B. None of the answer options is correct.

C. The X chromosome only carries genes dealing with being a female, so having another one doesn’t matter.

D. Only one X is active in each cell, regardless of how many X chromosomes there are in a cell.

E. We have enzymes that will recognize and degrade the extra X chromosome.

Answer 93

D. Only one X is active in each cell, regardless of how many X chromosomes there are in a cell.

Question 94

Which of the following is true?

A. Down syndrome is the one inherited disorder that results from an extra copy of an entire chromosome.

B. Down syndrome is caused by errors in fertilization.

C. Errors in chromosome segregation can occur in either the first or second meiotic division.

D. Nondisjunction can only produce gametes with extra chromosomes, not missing chromosomes.

Answer 94

C. Errors in chromosome segregation can occur in either the first or second meiotic division.

Question 95

In normal meiosis, when do homologous chromosomes separate from each other?

A. in the first meiotic division

B. in the second meiotic division

C. They may separate in either the first or second meiotic divisions.

Answer 95

A. in the first meiotic division

Question 96

What is nondisjunction?

A. failure of chromosomal replicationChoice

B. failure of chromosomal separation

C. failure of chromosomal condensation

D. failure of chromosomal pairing

Answer 96

B. failure of chromosomal separation

Question 97

If nondisjunction occurs in the first meiotic division, how many of the four possible gametes produced from meiosis will have the wrong number of chromosomes?

A. one

B. two

C. three

D. four

Answer 97

D. four

Question 98

In which type of nondisjunction could the two copies of a chromosome in a gamete be heterozygous?

A. nondisjunction in the first meiotic division

B. nondisjunction in the second meiotic division

C. Nondisjunction in either meiotic division could produce gametes with two copies of a chromosome that are heterozygous.

Answer 98

A. nondisjunction in the first meiotic division

Question 99

A complex trait can be influenced by the environment.

A. False

B. True

Answer 99

B. True

Question 100

Similar to single gene traits, traits determined by multiple genes also show the expected 3:1 ratio of phenotypes in the progeny between two heterozygotes.

A. False

B. True

Answer 100

A. False

Question 101

Most complex traits are: (Select all that apply.)

A. affected by interactions between genes and environmental factors.

B. affected by environmental factors.

C. heterozygous for all alleles affecting the trait.

D. affected by multiple genes.

E. inherited in pedigrees showing simple Mendelian patterns.

F. homozygous for all alleles affecting the trait.

Answer 101

A. affected by interactions between genes and environmental factors.

B. affected by environmental factors.

D. affected by multiple genes.

Question 102

Genotype-by-environment interaction means that genetic and environmental influences may interact or contribute to the phenotypic outcomes in unpredictable ways.

A. True

B. False

Answer 102

A. True

Question 103

Which of the following statements BEST reflects the extent to which we can distinguish the effects of genes and the environment on the expression of a complex trait?

A. None of answer options is correct.

B. For identical twins raised in the same environment, height should not differ by more than 20%.

C. About 80% of an individual’s height is determined by genes and 20% by environment.

D. If one individual is 60 inches tall and another is 70 inches tall, they differ in about 80% of their genes.

E. In a group of individuals of the same sex, about 80% of the variation in height among individuals is due to genetic differences and 20% is due to environmental differences.

Answer 103

E. In a group of individuals of the same sex, about 80% of the variation in height among individuals is due to genetic differences and 20% is due to environmental differences.

Question 104

Sunlight exposure has stronger effect on skin cancer risk in fair-skinned humans than in individuals with darker skin. This is an example of:

A. differences in the norm of reaction.

B. genotype-by-environment interaction.

C. epistasis.

D. All of these choices are correct.

E. pleiotropy.

Answer 104

B. genotype-by-environment interaction.

Question 105

Which of the following is not an example of a complex trait?

A. height in humans

B. milk production in dairy cows

C. smooth or wrinkled pea seeds

D. grain yield in corn

Answer 105

C. smooth or wrinkled pea seeds

Question 106

If all variation in height among humans was due to environmental influences alone, the mean height of offspring when graphed against the mean height of parents should be closest to which line in the graph above?

A. the parental mean line

B. the population mean line

Answer 106

B. the population mean line

Question 107

The actual offspring mean height in the graph lies between the parental mean line and the population mean because:

A. during meiotic cell division segregation and recombination break up combinations of genes leading to extreme phenotypes (e.g., very tall or very short).

B. the phenotypes of the parents result from both their genes and their environment.

C. the phenotypes of the offspring result from both their genes and their environment.

D. all of the above will affect the relationship between parent mean height and offspring mean height.

E. only choices a and c will affect the relationship between parent mean height and offspring mean height.

Answer 107

D. all of the above will affect the relationship between parent mean height and offspring mean height.

Question 108

The graph indicates that on average the offspring of short parents will be taller than their parents, and the offspring of tall parents will be shorter than their parents.

A. true

B. false

Answer 108

A. true

Question 109

A trait with high heritability responds rapidly to selection, whereas a trait with a low heritability responds slowly or not at all.

A. False

B. True

Answer 109

B. True

Question 110

If all variation among individuals in a population is due to differing genotypes alone, heritability is _____, and the slope of the line used to measure it is _____.

A. 100%; 1

B. 50%; 0.5

C. 50%; 1

D. 0%; 0

E. 100%; 0.5

Answer 110

A. 100%; 1

Question 111

An example of “regression toward the mean” would be if the offspring of two short parents had an average height equal to the average height of the parents?not of the population as a whole.

A. True

B. False

Answer 111

B. False

Question 112

When heritability is 0%, genes play:

A. a role in variation in the trait among individuals, but it cannot be measured.

B. no role in the expression of the trait.

C. a role in the expression of a trait, but only a small one.

D. no role in variation in the trait among individuals.

E. a role in the expression of a trait, but it can’t be measured.

Answer 112

D. no role in variation in the trait among individuals.

Question 113

The graph here shows the results of a controlled experiment where one strain of a crop plant is grown in soils with differing nitrogen concentrations.

If a different strain of the same plant were grown in the same soils, you would predict that:

A. it would respond completely differently to nitrogen supplementation because they are different strains.

B. it could respond the same way or differently; the environment has too many variables to predict.

C. it could respond the same way or differently; different genotypes can, but may not always, respond differently to the same range of environments.

D. None of the answer options is correct.

E. it would respond the same way to nitrogen supplementation because they are the same plant.

Answer 113

C. it could respond the same way or differently; different genotypes can, but may not always, respond differently to the same range of environments.

Question 114

A normal XY male has a son with the karyotype XYY. The likely explanation is:

A. second-division nondisjunction.

B. translocation.

C. copy-number variation.

D. first-division nondisjunction.

E. disjunction.

Answer 114

A. second-division nondisjunction.

Question 115

Which of the traits depicted here has the SMALLEST heritability?

A. trait K

B. trait H

C. trait M

D. trait L

Answer 115

D. trait L

Question 116

You are studying a large flock of chickens and divide it into two halves. Each half contains the same genetic variations at the same frequencies as in the other half. To one half (the control group) you feed normal chicken chow, to the other half (the experimental group) you feed normal chicken chow supplemented with a nutritional booster. As expected, in the experimental group the hens lay an average number of eggs greater than those in the control group. Yet the heritability remains the same in both the experimental and control groups. You can explain this observation by hypothesizing that the variation in nutrition among hens is:

A. larger in the control group.

B. the same in both groups.

C. smaller in the experimental group.

D. smaller in the control group.

E. larger in the experimental group.

Answer 116

B. the same in both groups.

Question 117

Shown here are two alleles of an SNP, one of which is associated with a higher risk of developing high blood pressure (hypertension).

Normal allele:

5’ -ATTCGCGGAATTCTGG -3’

3’ -TAAGCGCCTTAAGACC -5’

Allele associated with hypertension:

5’-ATTCGCGGGATTCTGG- 3’

3’-TAAGCGCCCTAAGACC -5’

You amplify DNA from multiple patients at a cardiologist’s office and digest each with EcoRI in order to determine the patients’ genotypes for this SNP. EcoRI recognizes the sequence below and cuts each strand at the locations indicated by the arrows.

Which lane in the gel below represents a sample from an individual heterozygous for this SNP?

A. lane D

B. lane C

C. lane B

D. lane A

E. lane E

Answer 117

C. lane B

Question 118

Shown here are two alleles of an SNP, one of which is associated with a higher risk of developing high blood pressure (hypertension).

Normal allele:

5’ -ATTCGCGGAATTCTGG -3’

3’ -TAAGCGCCTTAAGACC -5’

Allele associated with hypertension:

5’-ATTCGCGGGATTCTGG- 3’

3’-TAAGCGCCCTAAGACC -5’

You amplify DNA from multiple patients at a cardiologist’s office and digest each with EcoRI in order to determine the patients’ genotypes for this SNP. EcoRI recognizes the sequence below and cuts each strand at the locations indicated by the arrows.

Which lane in the gel below which lane represents an individual heterozygous for the hypertension allele?

A. lane E

B. lane B

C. lane C

D. lane A

Answer 118

B. lane B

Question 119

Shown here are two alleles of an SNP, one of which is associated with a higher risk of developing high blood pressure (hypertension).

Normal allele:

5’ -ATTCGCGGAATTCTGG -3’

3’ -TAAGCGCCTTAAGACC -5’

Allele associated with hypertension:

5’-ATTCGCGGGATTCTGG- 3’

3’-TAAGCGCCCTAAGACC -5’

You amplify DNA from multiple patients at a cardiologist’s office and digest each with EcoRI in order to determine the patients’ genotypes for this SNP. EcoRI recognizes the sequence below and cuts each strand at the locations indicated by the arrows.

Which lane in the gel below which lane represents an unaffected individual?

A. lane E

B. lane D

C. lane B

D. lane A

E. lane C

Answer 119

E. lane C

Question 120

Which of the following would be good examples of genotype-by-environment interactions? (Select all that apply.)

A. a line of chickens whose eggshells are extra thick regardless of feed type

B. two different mutants of mice that share similar fat metabolism abilities

C. a strain of corn whose yield varies with the amount of nutrients in the soil

D. a line of dairy cows that increases milk yield in relation to feed amount

E. a strain of mutant mice that becomes obese regardless of feed amount

F. two different strains of corn that differ in height due to genotype

Answer 120

C. a strain of corn whose yield varies with the amount of nutrients in the soil

D. a line of dairy cows that increases milk yield in relation to feed amount

Question 121

Diploid somatic cells of elephants have 56 chromosomes. If nondisjunction of one of an elephant’s chromosomes occurs in meiosis I, the resulting sperm are expected to have the following numbers of chromosomes:

A. 28, 28, 28, 28.

B. 28, 28, 29, 27.

C. 29, 29, 28, 28.

D. 29, 29, 27, 27.

E. 56, 56, 57, 55.

Answer 121

D. 29, 29, 27, 27.

Question 122

Shown here are two alleles of an SNP, one of which is associated with a higher risk of developing high blood pressure (hypertension).

Normal allele:

5’ -ATTCGCGGAATTCTGG -3’

3’ -TAAGCGCCTTAAGACC -5’

Allele associated with hypertension:

5’-ATTCGCGGGATTCTGG- 3’

3’-TAAGCGCCCTAAGACC -5’

You amplify DNA from multiple patients at a cardiologist’s office and digest each with EcoRI in order to determine the patients’ genotypes for this SNP. EcoRI recognizes the sequence below and cuts each strand at the locations indicated by the arrows.

Which lane in the gel below which lane represents an individual homozygous for the hypertension allele?

A. lane B

B. lane E

C. lane D

D. lane A

E. lane C

Answer 122

D. lane A

Question 123

An individual who is heterozygous for two linked genes (with alleles A, a and B, b) is crossed with an a b/a b individual, and among the progeny are the following:

14 A B/a b
36 A b/a b
34 a B/a b
16 a b/a b

What is the frequency of recombination?

A. 0.40

B. 0.70

C. 0.60

D. 0.35

E. 0.30

Answer 123

E. 0.30

Question 124

The fact that the ratio of human male to female births is nearly 1:1 demonstrates that:

A. X and Y chromosomes together determine sex.

B. X and Y chromosomes demonstrate segregation.

C. X and Y chromosomes demonstrate independent assortment.

D. All of these choices are correct.

X and Y chromosomes pair all along their length.

Answer 124

B. X and Y chromosomes demonstrate segregation.

Question 125

Review the pedigree shown in Figure 17.7 and choose the most accurate statement about the inheritance of an X-linked recessive mutation.

A. The offspring of an affected male are usually affected.

B. The sons of the sisters of affected males will always be affected.

C. The brothers of affected males are always affected.

D. Daughters of affected males are always affected.

E. For rare X-linked traits, most of the affected individuals are males.

Answer 125

E. For rare X-linked traits, most of the affected individuals are males.

Question 126

A restriction-fragment length polymorphism at a site in the X chromosome has three alleles, A1, A2, and A3. The gel below is the DNA fingerprint for two prospective parents (Mo and Fa) as well as DNA types that may (or may not) correspond to their possible offspring. What are the possible phenotypes of sons from this mating?

A. H and L

B. M and H

C. K and L

D. H and K

E. K and Q

Answer 126

E. K and Q

Question 127

Consider an X-linked restriction-fragment length polymorphism with alleles A1, A2, and A3. In the mating A1/A3 female × A2 male, what are the possible genotypes of the daughters? (Select all that apply.)

A. A1/A3

B. A2/A3

C. A1

D. A3

E. A1/A2

Answer 127

B. A2/A3

E. A1/A2

Question 128

An individual that is heterozygous for two linked genes has the genotype A b/a B, which means that the A and b alleles are in one chromosome and the a and B alleles in the homologous chromosome. Among the products of meiosis listed below, which are the recombinant types? (Select all that apply.)

A. A B

B. A b

C. a b

D. a B

Answer 128

A. A B

C. a b

Question 129

Mendel’s principle of segregation corresponds to what part of meiosis?

A. condensation of chromosomes in prophase I

B. alignment of chromosomes in metaphase II

C. separation of daughter chromatids in anaphase II

D. separation of homologs in anaphase I

E. alignment of homologs in metaphase I

Answer 129

D. separation of homologs in anaphase I

Question 130

Mendel’s principle of independent assortment corresponds to which part of meiosis?

A. separation of daughter chromatids during anaphase II

B. random alignment of homologs on the metaphase plate during metaphase I

C. separation of chromosomes in anaphase I

D. random alignment of homologs on the metaphase plate during metaphase II

E. random pairing of homologs during prophase I

Answer 130

B. random alignment of homologs on the metaphase plate during metaphase I

Question 131

Which of the following events occur during anaphase I of meiosis?

A. Homologous chromosomes move as one unit.

B. The centromeres of the chromosomes divide.

C. The chromosome number is doubled during this phase of meiosis.

D. In males, the X chromosome is segregated from the Y chromosome.

E. In females, the two X chromosomes remain together.

Answer 131

D. In males, the X chromosome is segregated from the Y chromosome.

Question 132

An XXY person inherited three sex chromosomes due to erroneous meiosis in the person’s parents. The syndrome associated with this particular aneuploidy is called Klinefelter Syndrome. This person can be: (Select all that apply.)

A. a male who received an X normally from his mom but an X and Y from his dad due to nondisjunction.

B. a female who received an X normally from her mom but an X and Y from her dad due to nondisjunction.

C. a female who received two X’s from her mom due to nondisjunction but a Y normally from her dad.

D. a male who received two X’s from his mom due to nondisjunction but a Y normally from his dad.

Answer 132

A. a male who received an X normally from his mom but an X and Y from his dad due to nondisjunction.

D. a male who received two X’s from his mom due to nondisjunction but a Y normally from his dad.

Question 133

You are given two true-breeding groups of rabbits. The first group has floppy ears and white coat color. The second group has straight ears and black coat color. When you perform a cross of these two groups to obtain an F1 generation, you see that all of your rabbits have floppy ears and grey coat color. Which of the following possibilities appears to be supported by what you see in the F1generation?

A. Straight ears are dominant over floppy ears; black coat color is dominant over white coat color.

B. Floppy ears are dominant over straight ears; black coat color is dominant over white coat color.

C. Floppy ears are dominant over straight ears; white coat color is dominant over black coat color.

D. Straight ears are dominant over floppy ears; coat color is determined by intermediate dominance.

E. Straight ears are dominant over floppy ears; white coat color is dominant over black coat color.

F. Floppy ears are dominant over straight ears; coat color is determined by incomplete dominance.

Answer 133

F. Floppy ears are dominant over straight ears; coat color is determined by incomplete dominance.

Question 134

The pedigree shown here pertains to a trait due to a rare, X-linked recessive mutation.

Individual 1 has no family history of the trait and individual 2 is affected, but the genotypes and phenotypes of individuals 1, 3, and 4 are unknown. What is the (approximate) probability that individual 1 is heterozygous? What is the probability that individual 3 is affected? What is the (approximate) probability that individual 4 is affected?

A. 1; 1; 1

B. 0; 0; 1

C. 1; 0; 0

D. 0; 0; 0

E. 0; 1; 0

Answer 134

D. 0; 0; 0

Question 135

In Mendel’s peas, an individual that is heterozygous for seed color:

A. will express the recessive allele.

B. has only one kind of allele for seed color.

C. has two different alleles for seed color and will express the dominant allele.

D. will express the dominant allele.

E. has two different alleles for seed color.

Answer 135

C. has two different alleles for seed color and will express the dominant allele.

Question 136

Given equal probabilities of the birth of a boy or girl, what is the probability that a group of four siblings includes all boys? All girls? All boys or all girls?

A. 1/16; 1/8; 3/8

B. 1/16; 1/16; 1/64

C. 1/8; 1/16; 3/8

D. 1/16; 1/16; 1/8

Answer 136

D. 1/16; 1/16; 1/8

Question 137

A male fly that is homozygous for recessive alleles at two linked autosomal loci is mated with a wild-type female fly that is homozygous dominant for both alleles. All F1 offspring are then randomly mated. If the loci are so close as to have no recombination, what proportion of offspring will be homozygous for both mutations in the F2 generation?

A. 3/4

B. 1/2

C. 1/4

D. 1/16

Answer 137

C. 1/4

Question 138

Inheritance due to a rare X-linked dominant mutation can be distinguished from inheritance due to a rare autosomal dominant mutation because, in the X-linked case:

A. the two possibilities cannot be distinguished.

B. affected mothers never has affected daughters.

C. affected fathers never has affected sons.

D. affected mothers never has affected sons.

E. affected fathers never has affected daughters.

Answer 138

C. affected fathers never has affected sons.

Question 139

A woman and a man are both heterozygous for a recessive allele for a rare genetic disease. If they have one child, what is the probability that he or she will be affected? If they have two children, what is the probability that at least one of them will be affected?

A. 7/16, 1/4

B. 1/4, 3/4

C. 3/4, 7/16

D. 3/4, 1/4

E. 1/4, 7/16

Answer 139

E. 1/4, 7/16

Question 140

A restriction-fragment length polymorphism at a site in the X chromosome has three alleles, A1, A2, and A3. The gel below is the DNA fingerprint for two girls who have the same parents. What is the genotype of the mother? Of the father?

A. A1/A3; A3

B. A1/A3; A2

C. A1/A3; A1

D. A1/A2; A3

E. A2/A3; A1

Answer 140

A. A1/A3; A3

Question 141

The bands observed in a gel for a VNTR (variable number of tandem repeats) polymorphism in a father (F) and mother (M) are shown in the accompanying diagram. What possible patterns of bands are expected among their offspring?

A. (1, 3), (1, 4), (2, 3), (2, 4)

B. (1, 2), (1, 4), (2, 3), (3, 4)

C. (1, 2), (1, 3), (2, 3), (3, 4)

D. (1, 3), (2, 3), (1, 4), (3, 4)

Answer 141

A. (1, 3), (1, 4), (2, 3), (2, 4)

Instructional Guidance: Students must understand segregation, which means that the offspring must get one band from the mother and one from the father, not both bands from one parent.

Question 142

In a cell undergoing meiosis, when a single crossover occurs between two genes of interest, the result is:

A. 4 chromosomes, all recombinant.

B. 4 chromosomes: 2 nonrecombinant and 2 recombinant.

C. 4 chromosomes, all nonrecombinant.

D. 4 chromosomes: 3 nonrecombinant and 1 recombinant.

E. 4 chromosomes: 1 nonrecombinant and 3 recombinant.

Answer 142

B. 4 chromosomes: 2 nonrecombinant and 2 recombinant.

Question 143

To discover the location of a genetic mutation that causes disease in humans, scientists use genetic mapping. Specifically, they look for genetic markers, or previously discovered DNA polymorphisms, that show statistical association with the disease gene. The statistical association means that the:

A. disease causes the DNA polymorphism.

B. DNA polymorphism causes the disease.

C. DNA polymorphism and the disease gene are unlinked.

D. DNA polymorphism and the disease gene are linked.

Answer 143

D. DNA polymorphism and the disease gene are linked.

Question 144

The pedigree shown here pertains to a trait due to a rare, X-linked recessive mutation.

Individual 1 has an affected brother, but the genotypes and phenotypes of individuals 1–4 are unknown. What is the probability that individual 1 is heterozygous? What is the probability that individual 3 is heterozygous? What is the probability that individual 4 is affected?

A. 1; 1/2; 1/2

B. 1/2; 1/2; 1/2

C. 1/2; 1/4; 1/4

D. 1; 1/4; 1/2

E. 1/2; 1/2; 1/4

Answer 144

C. 1/2; 1/4; 1/4

Question 145

What is the HIGHEST recombination frequency possible between two genes in the same chromosome?

A. 100%

B. The value depends on the chromosome in question.

C. 75%

D. 25%

E. 50%

Answer 145

E. 50%

Question 146

Assuming that the trait represented by the filled symbols below is a rare inherited trait with complete penetrance due to a single gene with alleles A and a, what mode of inheritance does the pedigree suggest?

A. recessive

B. dominant

Answer 146

A. recessive

Question 147

In the pedigree above, what can you say about the likely genotypes of individuals A and B?

A. one is AA and the other is Aa

B. both are AA

C. It is not possible to determine this for certain from the information provided.

D. both are Aa

Answer 147

D. both are Aa

Question 148

Consider a gene with four alleles A1, A2, A3, and A4. How many distinct genotypes are possible, taking into account both homozygous and heterozygous genotypes?

A. 8

B. 9

C. 7

D. 6

E. 10

Answer 148

E. 10

Question 149

In pea plants, flowers are either white or purple; the purple color is produced by pigments called anthocyanins. The production of anthocyanins is a two-step process: the first is controlled by the Cgene and the second by the P gene. The genes are not linked and both must produce functional proteins for anthocyanin to be expressed. For each gene, the dominant (C and P) alleles produce functional proteins. You cross two pea plants, each with the genotype CcPp. What proportion of their offspring will have white flowers?

A. 3/4

B. 9/16

C. 7/16

D. 13/16

E. 1/4

Answer 149

C. 7/16

Question 150

The pedigree shown here pertains to a trait due to a rare, X-linked recessive mutation.

Individual 1 has an affected grandfather, but the genotypes and phenotypes of individuals 1–4 are unknown. What is the probability that individual 1 is heterozygous? What is the probability that individual 3 is heterozygous? What is the probability that individual 4 is affected?

A. 1/2; 1/4; 1/2

B. 1/2; 1/4; 1/4

C. 1; 1/2; 1/2

D. 1/2; 1/2; 1/2

E. 1; 1/4; 1/4

Answer 150

B. 1/2; 1/4; 1/4

Question 151

The genetic map shown here depicts the locations of five single-nucleotide polymorphisms (SNPs, designated a–e) in an autosome and the frequency of recombination (in percent) between adjacent SNPs. The region includes a genetic risk factor Q for a disease, which may be located at position M, H, K, or L.

Pedigree studies indicate that the frequencies of recombination between each of the SNPs and Q are as follows:
percent recombination a–Q equals 10%
percent recombination b–Q equals 6%
percent recombination c–Q equals 6%
percent recombination d–Q equals 14%
percent recombination e–Q equals 30%

What is the MOST likely position of Q in the genetic map?

A. position K

B. position M

C. position L

D. position H

E. None of the answer options is correct.

Answer 151

D. position H

Question 152

In genetics, the dash symbol (–) is a “wild card” that stands for either the dominant allele or the recessive allele; for example, A– means the individual has either the genotype AA or Aa. Two genes that undergo independent assortment affect flower color in sweet peas. Each gene as two alleles, one of which is dominant for flower color. Genotypes of the form A– B– have purple flowers, whereas those of the form A– bb, aa B–, and aa bb have white flowers. What ratio of purple : white is expected from the cross Aa Bb × Aa Bb?

A. 15:1

B. 10:6

C. 12:4

D. 9:7

E. 13:3

Answer 152

D. 9:7

Instructional Guidance: This type of epistasis is known as “duplicate recessive epistasis.”

Question 153

All the alleles present in all individuals in a species are referred to as the _____ of that species.

A. gene pool

B. phenotype

C. genotype

E. allele frequency

F. genotype frequency

Answer 153

A. gene pool

Question 154

Genetic variation has two sources–mutation and:

A. natural selection.

B. non-random mating.

C. genetic drift.

D. cell division.

E. recombination.

Answer 154

E. recombination.

Question 155

What is the result of a mutation that occurs in somatic cells?

A. There will never be any visible effect.

B. The mutation will be passed along to the organism’s offspring.

C. The mutation may be expressed in the individual, but will not be passed along to its offspring.

D. The mutation will prevent all reproduction.

E. The mutation will be deleterious.

Answer 155

C. The mutation may be expressed in the individual, but will not be passed along to its offspring.

Question 156

As a population geneticist, you find a species of snails with more genetic diversity than humans. What does this mean?

A. There is more variety in the gene pool of snails than humans.

B. The snails have more DNA than humans.

C. The snails have more mutations occurring than humans.

D. The snails have more genes on their chromosomes than humans.

E. There is not enough information provided to answer this question.

Answer 156

A. There is more variety in the gene pool of snails than humans.

Question 157

Consider a population of killer whales. The gene pool of this population would only contain alleles harboring beneficial or neutral mutations, as deleterious mutations are efficiently eliminated from the gene pool of a species.

A. True

B. False

Answer 157

B. False

Question 158

If a gene has two alleles, and allele A has a frequency of 83%, then allele a has a frequency of:

A. 7%.

B. 166%.

C. 17%.

D. 117%.

E. 41.5%.

Answer 158

C. 17%.

Question 159

Why can’t we measure genetic variation in a population using observable traits (phenotypes)? (Select all that apply.)

A. The environment can also affect the phenotype.

B. All traits are encoded by a single gene.

C. Phenotypes are not determined by genes.

D. Many traits are encoded by multiple genes.

Answer 159

A. The environment can also affect the phenotype.

D. Many traits are encoded by multiple genes.

Question 160

In a given population, all humans have the same blood type O. If no other alleles for blood type exist in this population, this population is “fixed” for the O allele.

A. False

B. True

Answer 160

B. True

Question 161

In a fish species the eggs tend to be fertilized more often by the mid-sized males and less often by the largest and smallest males. This is an example of:

A. stabilizing selection.

B. directional selection.

C. disruptive selection.

D. None of the other answer options is correct.

Answer 161

A. stabilizing selection.

Question 162

A cattle breeder selects the largest males for breeding with the largest females. This is an example of:

A. stabilizing selection.

B. directional selection.

C. disruptive selection.

D. None of the other answer options is correct.

Answer 162

B. directional selection.

Question 163

Female starlings (birds) that lay clutches of four or five eggs have more surviving young than those with either larger or smaller clutches. This is an example of:

A. stabilizing selection.

B. directional selection.

C. disruptive selection.

D. None of the other answer options is correct.

Answer 163

A. stabilizing selection.

Question 164

On Island X the plant population contains only two species. One plant species produces only very large seeds, and the other produces only small seeds. There is only one species of bird on the island, and the birds use these seeds as their only food source. Currently there is a wide range of beak sizes within the population of birds as shown in the diagram below. Small-beaked birds are better able to consume the smaller seeds, while large-beaked birds are better at consuming the larger seeds. Birds with intermediate beak size can make use of both seed sizes.

A disease is introduced to the island which kills only the plants that produce the large seeds. Consider changes in the bird population following the death of all plants that produce large seeds. Which portion(s) of the finch population will be selected againstand least likely to have their genes represented in the next generations?

A. portion A only

B. portion B only

C. portion C only

D. portions A and C simultaneously

E. portions B and C simultaneously

Answer 164

C. portion C only

Question 165

What type of selection occurs when an environmental condition, for example food source characteristics, causes selection toward one extreme of a trait’s range of variation?

A. stabilizing

B. directional

C. disruptive

Answer 165

B. directional

Question 166

On Island X the plant population contains only two species. One plant species produces only very large seeds, and the other produces only small seeds. A rare storm blows in a flock of birds of a species never before found on the island. Within this flock there is a wide range of beak sizes as shown in the diagram here.

As their only food source, the birds find the plant seeds quite delectable. However, while small-beaked birds do very well consuming the smaller seeds, and large-beaked birds thrive on the larger seeds, birds with intermediate beak size are not good at consuming either size seed, and they struggle to get sufficient nutrition. What type of selection might we predict over the course of multiple generations of these birds?

A. stabilizing

B. directional

C. disruptive

Answer 166

C. disruptive

Question 167

Malthus pointed out that populations have the potential to increase geometrically. What did this observation suggest that contributed to the idea of natural selection?

A. Populations may grow quickly and spread out over the planet.

B. Populations may grow faster than other competing populations.

C. Populations grow quickly, but predators grow more quickly.

D. Populations may grow faster than their resources.

E. Populations may grow quickly, and then will evolve more quickly.

Answer 167

D. Populations may grow faster than their resources.

Question 168

The intricate plumage of male birds of paradise has become increasingly elaborate throughout their evolution due to females mating preferentially with males that display the most impressive feathers. This is an example of _____ selection.

A. sexual

B. artificial

C. disruptive

D. stabilizing

Answer 168

A. sexual

Question 169

Prior to the publication of Darwin’s On the Origin of Species, people thought what about species?

A. Species evolved at one point, but no longer changed because they were not adapted to their environment.

B. Species changed over time as guided by a divine creator.

C. Species were designed already perfectly adapted to their environment.

D. Species changed over time because they were not adapted to their environment.

Answer 169

C. Species were designed already perfectly adapted to their environment.

Question 170

Traits favored by sexual selection are the same traits favored by natural selection.

A. True

B. False

Answer 170

B. False

Question 171

The goldenrod gall fly lays its eggs on the terminal buds of goldenrod plants. Larvae chew through the buds and into the stems, where their saliva induces the plant to generate a gall, or outgrowth of tissue that then provides food and shelter for the developing larva. The larvae are prey to both parasitoid wasps and to birds; wasps selectively prey on larvae inside the smallest galls while birds selectively prey on larvae inside the largest galls. Goldenrod gall flies are therefore subject to _____ selection.

A. balancing

B. heterozygote

C. directional

D. disruptional

E. stabilizing

Answer 171

E. stabilizing

Question 172

Which of the following is an example of stabilizing selection?

A. decrease in the number of birds with intermediate-sized beaks who are unable to eat large or small seeds

B. selection for average birth weight in humans

C. antibiotic resistance in bacteria

D. breeding dogs from wolves

Answer 172

B. selection for average birth weight in humans

Question 173

Why is it thought that the majority of natural selection is stabilizing selection?

A. Most mutations are beneficial and produce intermediate phenotypes.

B. Artificial selection is the most common, which is a type of stabilizing selection.

C. Most mutations are deleterious and produce an extreme phenotype that is selected against.

D. Directional selection is more common because it increases adaptations to the environment.

E. Mutations produce extreme phenotypes, which are selected for.

Answer 173

C. Most mutations are deleterious and produce an extreme phenotype that is selected against.

Question 174

Meerkats are small desert mammals that live in groups of 20–50 individuals. You observe one meerkat standing upright on a stump, looking around, while other meerkats forage for food. You hypothesize that this is an example of kin selection. What additional information would you need to know to evaluate your hypothesis?

A. the body size of this meerkat relative to other members of the group

B. the degree of genetic relatedness of this meerkat to all members of the group

C. the foraging success of this meerkat as well as that of all other members of the group

D. all other activities of this meerkat as well as those of all other members of the group

E. the gender of this meerkat as well as that of all other members of the group

Answer 174

B. the degree of genetic relatedness of this meerkat to all members of the group

Question 175

If B = the benefit of a behavior to a recipient, C = the cost of the behavior of the donor, and r = the degree of relatedness between the recipient and donor, then if rB > C, altruism can evolve.

A. False

B. True

Answer 175

B. True

Question 176

According to William Hamilton’s formulation of kin selection, in which scenario would you have the greatest fitness? Use Figure 45.17 below for help.

A. Sacrificing yourself for the benefit of two nieces and/or nephews.

B. Sacrificing yourself for the benefit of three nieces and/or nephews.

C. Sacrificing yourself for the benefit of one sibling.

D. Sacrificing yourself for the benefit of one child.

Answer 176

B. Sacrificing yourself for the benefit of three nieces and/or nephews.

Question 177

Group selection is not typically seen as an evolutionarily stable strategy because:

A. selfish behaviors are more likely to increase individual fitness.

B. None of the answer options is correct.

C. it cannot explain behaviors for species with solitary individuals.

D.average relatedness is very low between individuals in a population, therefore individual fitness cannot increase.

Answer 177

A. selfish behaviors are more likely to increase individual fitness.

Question 178

If a population is not in Hardy-Weinberg equilibrium, we can conclude that:

A. natural selection has occurred.

B. one of the assumptions of the Hardy-Weinberg equilibrium has been violated.

C. evolution has occurred because one or more of the assumptions of the Hardy-Weinberg equilibrium has been violated.

D. nonrandom mating has occurred.

E. All of these choices are correct.

Answer 178

C. evolution has occurred because one or more of the assumptions of the Hardy-Weinberg equilibrium has been violated.

Question 179

What does the term 2pq represent in the Hardy-Weinberg relation?

A. the frequency of homozygous dominant individuals

B. the frequency of heterozygotes

C. the frequency of homozygous recessive individuals

D. the frequency of deleterious mutations

Answer 179

B. the frequency of heterozygotes

Question 180

Which of the following is NOT a condition of the Hardy-Weinberg equilibrium?

A. Mutations cannot occur in a population.

B. Mating within a population must be random.

C. Individuals of any genotype must have the same reproductive success as individuals of any other genotype.

D. The size of a population must be large.

E. Individuals can migrate in and out of a population, as long as the population size remains constant.

Answer 180

E. Individuals can migrate in and out of a population, as long as the population size remains constant.

Question 181

What term CORRECTLY describes change in allele frequency due to random effect of a small population?

A. immigration

B. selection

C. nonrandom mating

D. mutation

E. genetic drift

Answer 181

E. genetic drift

Question 182

You are given the following information about a population:
• There are two alleles: C and c.
• C codes for green hair and c codes for white hair.
• C is dominant over c.
• The frequency of the c allele is 0.3.
• The population is comprised of 100 individuals.
Assuming the population is in Hardy-Weinberg equilibrium, how many individuals have green hair?

A. 49% of the population will have green hair.

B. 51% of the population will have green hair.

C. 9% of the population will have green hair.

D. 91% of the population will have green hair.

Answer 182

D. 91% of the population will have green hair.

Question 183

Why does genetic drift have more of an impact on the evolution of small populations than large ones?

A. Small populations are more prone to migration.

B. Small populations are less affected by mutations.

C. Small populations have greater rates of mutation.

D. Small populations are affected more by stabilizing selection.

E. Sampling from generation to generation is more variable in small populations than large.

Answer 183

E. Sampling from generation to generation is more variable in small populations than large.

Question 184

Mutation increases genetic variation.

A. False

B. True

Answer 184

B. True

Question 185

Imagine the following genotype frequencies in a population: p2 = 0.49, 2pq = 0.42, q2 = 0.09. Now assume that there is nonrandom mating where individuals with one genotype will only mate with individuals that also have their genotype. Assume this pattern of mating goes on until the frequency of heterozygotes is effectively zero. What will the frequency of allele p be in the population?

A. 1.0

B. 0.91

C. 0.49

D. 0.7

E. 0.3

Answer 185

D. 0.7

Question 186

You are researching a population of moles. In the course of your research, you identify a nearby population that occasionally comes into contact with your study population. What BEST describes the evolutionary process at work?

A. mutation

B. genetic drift

C. gene flow

D. artificial selection

E. natural selection

Answer 186

C. gene flow

Question 187

Endangered species with very small populations are especially at risk of loss of genetic diversity due to:

A. mutation.

B. immigration.

C. genetic drift.

D. natural selection.

Answer 187

C. genetic drift.

Question 188

Migration reduces genetic differences between populations by allowing gene _____ between the two.

A. repression

B. deletion

C. augmentation

D. flow

E. drift

Answer 188

D. flow

Question 189

The correlation between the time two species have been evolutionarily separated and the amount of genetic divergence between them is known as the:

A. Hardy-Weinberg equilibrium.

B. Modern Synthesis.

C. molecular clock.

D. artificial selection.

E. natural selection.

Answer 189

C. molecular clock.

Question 190

A gene that no longer retains function is called:

A. negatively selected.

B. a terminal gene.

C. a pseudogene.

D. broken.

E. a gene with a stopped molecular clock.

Answer 190

C. a pseudogene.

Question 191

Two populations that have been separated from each other for a long period of time will have:

A. substantial differences between their genetic sequences.

B. no similar genetic sequences.

C. no differences between their genetic sequences.

D. small differences in phenotype but identical genotypes.

E. limited differences between their genetic sequences.

Answer 191

A. substantial differences between their genetic sequences.

Question 192

If two populations are thought to be diverging from one another, what would you expect to observe?

A. an increase in similarity of alleles coding for proteins

B. an accumulation of different mutations in different populations

C. the same genotypes, but different phenotypes

D. more shared mutations in different populations

Answer 192

B. an accumulation of different mutations in different populations

Question 193

Some proteins have a slower molecular clock due to _____ selection, which eliminates harmful alleles.

A. neutral

B. negative

C. disruptive

D. positive

E. beneficial

Answer 193

B. negative

Question 194

During DNA replication occasional errors can occur resulting in a change in a nucleotide base, for example instead of adding a T, a C is added. If this is not corrected by mismatch repair or other mechanisms, this change represents a:

A. selection.

B. deletion.

C. transformation.

D. mutation.

E. conversion.

Answer 194

D. mutation.

Question 195

The fur color in a colony of mice has been brown for many generations. One gene appears to code for the fur color pigment. In a recent litter of mouse pups, one mouse was born with white fur. Which of the following could have caused this change in fur color?

A. a mutation in the DNA sequence of the gene for brown fur

B., recombination between genes for fur color

C. All of these choices are correct.

Answer 195

A. a mutation in the DNA sequence of the gene for brown fur

Question 196

Females of a species of parasitic wasps locate their prey, a leaf-eating caterpillar, by hunting for it visually. One year, one female appeared in the wasp population with the ability to locate the prey by smell. The most likely place of occurrence of the mutation causing this change was:

A. in the DNA in one of the egg cells in the individual with the new phenotype.

B. in the DNA in the egg cell that developed into the individual with the new phenotype.

C. in the DNA of one of the olfactory (smell) receptor cells on one antenna of the individual with the new phenotype.

D. in the DNA of the cells in the wasp’s eye.

Answer 196

B. in the DNA in the egg cell that developed into the individual with the new phenotype.

Question 197

Two alleles of a given gene exist in a population: CTGT and TGTC. (Note: The codes given are only for the transcribed strand of the DNA in the two alleles.) Three possible single crossover events are possible between these two alleles. As a result of the three different crossover events, how many total new alleles (new sequences of DNA) could be produced?

A. 3

B. 4

C. 5

D. 6

E. 12

Answer 197

D. 6

Question 198

In a fish species the eggs tend to be fertilized more often by the mid-sized males and less often by the largest and smallest males. This is an example of:

A. stabilizing selection.

B. directional selection.

C. disruptive selection.

D. None of the other answer options is correct.

Answer 198

A. stabilizing selection.

Question 199

A cattle breeder selects the largest males for breeding with the largest females. This is an example of:

A. stabilizing selection.

B. directional selection.

C. disruptive selection.

D. None of the other answer options is correct.

Answer 199

B. directional selection.

Question 200

Female starlings (birds) that lay clutches of four or five eggs have more surviving young than those with either larger or smaller clutches. This is an example of:

A. stabilizing selection.

B. directional selection.

C. disruptive selection.

D. None of the other answer options is correct.

Answer 200

A. stabilizing selection.

Question 201

On Island X the plant population contains only two species. One plant species produces only very large seeds, and the other produces only small seeds. There is only one species of bird on the island, and the birds use these seeds as their only food source. Currently there is a wide range of beak sizes within the population of birds as shown in the diagram below. Small-beaked birds are better able to consume the smaller seeds, while large-beaked birds are better at consuming the larger seeds. Birds with intermediate beak size can make use of both seed sizes.

A disease is introduced to the island which kills only the plants that produce the large seeds. Consider changes in the bird population following the death of all plants that produce large seeds. Which portion(s) of the finch population will be selected againstand least likely to have their genes represented in the next generations?

A. portion A only

B. portion B only

C. portion C only

D. portions A and C simultaneously

E. portions B and C simultaneously

Answer 201

C. portion C only

Question 202

What type of selection occurs when an environmental condition, for example food source characteristics, causes selection toward one extreme of a trait’s range of variation?

A. stabilizing

B. directional

C. disruptive

Answer 202

B. directional

Question 203

On Island X the plant population contains only two species. One plant species produces only very large seeds, and the other produces only small seeds. A rare storm blows in a flock of birds of a species never before found on the island. Within this flock there is a wide range of beak sizes as shown in the diagram here.

As their only food source, the birds find the plant seeds quite delectable. However, while small-beaked birds do very well consuming the smaller seeds, and large-beaked birds thrive on the larger seeds, birds with intermediate beak size are not good at consuming either size seed, and they struggle to get sufficient nutrition. What type of selection might we predict over the course of multiple generations of these birds?

A. stabilizing

B. directional

C. disruptive

Answer 203

C. disruptive

Question 204

Which of the following is not a contributor to genetic drift?

A. founder event

B. bottleneck

C. random change in allele frequency

D. natural selection

E. population size

Answer 204

D. natural selection

Question 205

Genetic drift is more likely to cause evolution in a small population than in a large one because:

A. mutation rates are higher in small populations.

B. random events occur more often in small populations.

C. with fewer individuals, which individuals mate can have larger effects in small populations.

D. All of these choices are correct.

Answer 205

C. with fewer individuals, which individuals mate can have larger effects in small populations.

Question 206

Suppose a neutral allele arises in a small population of organisms. Which of the following is/are most likely to occur over subsequent generations? Select all that apply.

A. The allele could increase in frequency and reach fixation.

B. The allele could completely disappear (go extinct).

C. The allele could remain in the gene pool indefinitely (neither fixation nor extinction).

Answer 206

A. The allele could increase in frequency and reach fixation.

B. The allele could completely disappear (go extinct).

Question 207

Suppose a neutral allele arises in a large population of organisms. Which of the following is/are most likely to occur over subsequent generations? Select all that apply.

A. The allele could increase in frequency and reach fixation.

B. The allele could completely disappear (go extinct).

C. The allele could remain in the gene pool indefinitely (neither fixation nor extinction).

Answer 207

C. The allele could remain in the gene pool indefinitely (neither fixation nor extinction).

Question 208

Which of the following is not an example of a complex trait?

A. height in humans

B. milk production in dairy cows

C. smooth or wrinkled pea seeds

D. grain yield in corn

Answer 208

C. smooth or wrinkled pea seeds

Question 209

If all variation in height among humans was due to environmental influences alone, the mean height of offspring when graphed against the mean height of parents should be closest to which line in the graph above?

A. the parental mean line

B. the population mean line

Answer 209

B. the population mean line

Question 210

The actual offspring mean height in the graph lies between the parental mean line and the population mean because:

A. during meiotic cell division segregation and recombination break up combinations of genes leading to extreme phenotypes (e.g., very tall or very short).

B. the phenotypes of the parents result from both their genes and their environment.

C. the phenotypes of the offspring result from both their genes and their environment.

D. all of the above will affect the relationship between parent mean height and offspring mean height.

E. only choices a and c will affect the relationship between parent mean height and offspring mean height.

Answer 210

D. all of the above will affect the relationship between parent mean height and offspring mean height.

Question 211

The graph indicates that on average the offspring of short parents will be taller than their parents, and the offspring of tall parents will be shorter than their parents.

A. true

B. false

Answer 211

A. true

Question 212

Unlike the biological species concept, the morphospecies concept relies on:

A. offspring.

B. phenotype.

C. behavior.

D. physiology.

Answer 212

B. phenotype.

Question 213

Which of the following statements is TRUE regarding hybridization?

A. Hybridization occurs in plants more often than in animals.

B. Natural selection sometimes acts against progeny that result from hybridization.

C. All of these choices are correct.

D. Hybridization can result in fertile offspring.

E. Hybridization involves the transfer of genetic material between members of similar species.

Answer 213

C. All of these choices are correct.

Question 214

While in South America, you come across what you think are two groups of birds in the same location. They are nearly identical aside from their color. After years of observation, you conclude that the birds eat similar diets and share similar behaviors but do not reproduce with each other. These groups of birds appear to be an example of:

A. two different species on the basis of the ecological niche occupied.

B. a single biological species.

C. a single ecological species.

D. ring species.

E. two different species on the basis of reproductive behavior.

Answer 214

E. two different species on the basis of reproductive behavior.

Question 215

Which of the following species concepts might differentiate species on the basis of specific dietary requirements?

A. ecological species

B. evolutionary species

C. ring species

Answer 215

A. ecological species

Question 216

Two species of frog mate in the same pond. One breeds in early summer and one in late summer. This is an example of what kind of reproductive isolation?

A. pre-zygotic, behavioral isolation

B. pre-zygotic, ecological separation

C. post-zygotic, ecological separation

D. post-zygotic, temporal separation

E. pre-zygotic, temporal separation

Answer 216

E. pre-zygotic, temporal separation

Question 217

You are an experienced naturalist and biologist and you observe two birds mating that you do not believe to belong to the same species. The eggs from this breeding do not hatch, and when you obtain one of the eggs, you find embryonic development stopped not long after fertilization. Which of the following conclusions is supported by these observations?

A. Pre-zygotic isolation prevented successful reproduction.

B. Behavioral isolation prevented successful reproduction.

C. Post-zygotic factors prevented successful reproduction.

D. Temporal isolation prevented successful reproduction.

E. This is evidence to suggest the two types of birds are a single species.

Answer 217

C. Post-zygotic factors prevented successful reproduction.

Question 218

In the southwestern desert of the United States there are temporary ponds that form only after heavy summer rains. As a naturalist, you visit these ponds and notice that female frogs mate with males of their own species based only on their calls. The lack of mating between different species would be an example of _____ and _____.

A. post-zygotic isolation; temporal separation

B. pre-zygotic isolation; behavioral isolation

C. pre-zygotic isolation; temporal separation

D. post-zygotic isolation; behavioral isolation

Answer 218

B. pre-zygotic isolation; behavioral isolation

Question 219

You would expect similar species with a different number of chromosomes to be genetically compatible and therefore able to reproduce.

A. False

B. True

Answer 219

A. False

Question 220

The reason that lions (which live in Africa) and tigers (which live in Asia) don’t produce ligers (infertile offspring of lions and tigers) in the wild is likely the result of:

A. both temporal and ecological separation of lions and tigers.

B. ecological separation of lions and tigers.

C. temporal separation of lions and tigers.

D. an incompatible lock-and-key mechanism between the species.

E. behavioral isolation of tigers and lions.

Answer 220

B. ecological separation of lions and tigers.

Question 221

The longer two species have been separated, the greater the number of genetic differences between them.

A. True

B. False

Answer 221

A. True

Question 222

True or False: When individuals of a parent species are separated geographically, one population of separated individuals is more likely to acquire neutral mutations than the other.

A. True

B. False

Answer 222

B. False

Question 223

In animals with alleles for a given trait of A and a, if Hardy-Weinberg conditions are met, which one of the following is not a possible genotype frequency? For a hint, click on the check mark next to “Hardy-Weinberg” at the top. Click the x box to turn it off when you’re done.

A. p2

B. q2

C. 2pq

D. p2q2

E. Each of the genotype frequencies provided is a possibility.

Answer 223

D. p2q2

Question 224

True or False: An allele that has acquired a mutation at a particular nucleotide position is just as likely to acquire a subsequent mutation as an allele which has not been previously mutated.

A. True

B. False

Answer 224

A. True

Question 225

Neutral mutations can increase in frequency to a maximum of what percentage of the population?

A. 25%

B. 50%

C. 75%

D. 99%

E. 100%

Answer 225

E. 100%

Question 226

Neutral mutations can decrease in frequency to a minimum of what percentage of the population?

A. 0%

B. 5%

C. 10%

D. 25%

E. 50%

Answer 226

A. 0%

Question 227

A neutral mutation is one that:

A. increases survival and/or reproduction.

B. decreases survival and/or reproduction.

C. does not affect survival or reproduction.

Answer 227

C. does not affect survival or reproduction.

Question 228

Speciation is said to occur when: (For a hint, reset the map and click on the purple double-headed arrow. Click on the arrows again when you are done.)

A. two populations become completely reproductively isolated from one another.

B. any two mutations become fixed differences between the populations.

C. partial reproductive isolation between two populations is achieved.

D. two populations become permanently physically separated from each other.

E. all deleterious mutations have been eliminated from the populations.

Answer 228

A. two populations become completely reproductively isolated from one another.

Question 229

If the environmental conditions change, a neutral mutation can become advantageous or disadvantageous.

A. true

B. false

Answer 229

A. true

Question 230

If the frequency of the blue trait changes randomly in the population from generation to generation, the most likely cause for this is:

A. genetic drift.

B. natural or artificial selection.

C. mutation.

D. epigenetic inheritance.

Answer 230

A. genetic drift.

Question 231

Which of the following factors would be least likely to affect the mutation rate in a population?

A. age of the males reproducing in a sexual population

B. the presence of mutagens in the environment

C. the level of recombination in a population

D. generation time of the species

Answer 231

C. the level of recombination in a population

Question 232

The following numbers represent the numbers of genotypes coding for blue, red, and green coloration in the fish population. The numbers are shown for three successive generations of the population.

The allele and genotype frequencies in Generation 3 are:

A. B = 0.25, G = 0.25; BB = 0.50, BG = 0.25, GG = 0.50.

B. B = 0.50, G = 0.50; BB = 0.40, BG = 0.20, GG = 0.40.

C. B = 0.50, G = 0.50; BB = 0.50, BG = 0.25, GG = 0.50.

D. B = 0.50, G = 0.50; BB = 0.50, BG = 0, GG = 0.50.

Answer 232

B. B = 0.50, G = 0.50; BB = 0.40, BG = 0.20, GG = 0.40.

Question 233

The following numbers represent the numbers of genotypes coding for blue, red, and green coloration in the fish population. The numbers are shown for three successive generations of the population.

Which of the following is the most likely mechanism operating to produce the results shown for the three generations in the table?

A. stabilizing selection

B. directional selection

C. disruptive selection

D. balancing selection

Answer 233

C. disruptive selection

Question 234

The following numbers represent the numbers of genotypes coding for blue, red, and green coloration in the fish population. The numbers are shown for three successive generations of the population.

Which of the following scenarios could not explain the changes in genotype frequencies above?

A. The blue and green fish prefer differ food sources.

B. The red fish are poorly adapted to the environment (disfavored by selection).

C. The blue and green fish preferentially mate with their own type.

D. There is random mating among all of the fish genotypes.

Answer 234

D. There is random mating among all of the fish genotypes.

Question 235

REMINDER: Go over “Working With Data: Fig 22.7 copy” from Week 5 Launchpad

Answer 235

NOW!