Deck 4: Sex Determination and Sex-Linked Characteristics

Question 1

What is the sex chromosome constitution of a male duck-billed platypus?

A)XX
B)XY
C)XO
D)ZZ
E)XXXXXYYYYY

Answer 1

E

Question 2

In which of the following individuals would you expect to find two Barr bodies in their somatic cells?

A)XX
B)XO
C)XXY
D)XXYY
E)XXX

Answer 2

E

Question 3

Women with Turner syndrome (XO)and normal women (XX)are clearly different phenotypically.In addition, the vast majority of XO conceptions abort before birth.However, both XO and XX women have one active X chromosome since the X in XO women remains active and one might expect that they would therefore have similar phenotypes.What is the MOST reasonable explanation for their different phenotypes?

A)XO women do not have a copy of the SRY gene.
B)Some genes remain active on the inactive X chromosome, and XX women will have two copies of these genes expressed while XO women only have one copy expressed.
C)In XO women, the single X chromosome has no partner to pair with during mitosis so that each cell division is delayed by pairing problems with the single X not finding a pairing partner.
D)XO women have two copies of the SRY gene so that they are forced to develop partway along the male pathway during embryogenesis.
E)None of these are reasonable explanations.

Answer 3

B

Question 4

With the XX-XO sex determination system, generally:

A)female offspring have one X chromosome, and it is inherited from their father.
B)male offspring have one X chromosome, and it is inherited from their mother.
C)male offspring have one X chromosome, and it is inherited from their father.
D)female offspring have one X chromosome, and it is inherited from their mother.
E)None of the statements is true.

Question 5

In which of the following organisms is gender/sex determined by the temperature during embryonic development?

A)Humans
B)Mice
C)Fruit flies
D)Many snakes and all birds
E)Many turtles and alligators

Question 6

What is the role of the SRY gene in humans?

A)It initiates the X inactivation process in females.
B)It is located on the X chromosome and causes the X to pair with the Y chromosome during male meiosis.
C)It is located on the Y chromosome and initiates the developmental pathway toward the male phenotype.
D)It is located on an autosomal chromosome and represses expression of autosomal genes in order to balance their expression level with genes on the X chromosome.
E)None of the answers is correct.

Question 7

In species of birds, males are the homogametic sex and females the heterogametic sex.Which if the following is TRUE in this system of sex determination?

A)The gender of the offspring is determined by the female parent.
B)Male offspring have a ZW chromosome constitution.
C)The gender of the offspring is determined by the male parent.
D)Female offspring have a ZZ chromosome constitution.
E)Female and male offspring have the same chromosome constitution.

Question 8

A Barr body is a(n):

A)gene on the X chromosome that is responsible for female development.
B)patch of cells that has a phenotype different from surrounding cells because of variable X inactivation.
C)inactivated X chromosome, visible in the nucleus of a cell that is normally from a female mammal.
D)extra X chromosome in a cell that is the result of nondisjunction.
E)extra Y chromosome in a cell that is the result of nondisjunction.

Question 9

In a germ-line cell from a human male that is dividing, when do the X and Y chromosomes segregate?

A)During mitosis
B)During meiosis
C)They do not segregate; gametes contain a copy of X and a copy of Y.
D)Immediately after fertilzation.
E)None of the answers is correct.

Question 10

Which of the following chromosome constitutions would never lead to a viable human baby being born?

A)XXX
B)XYY
C)XO (O = the absence of a second chromosome)
D)YY
E)XXY

Question 11

Human males, with XY chromosomes are _____ and produce two different kinds of gametes, whereas females with XX chromosomes are _____ and produce only one kind.

A)homogametic; heterogametic
B)pleiotropic: epistatic
C)heterogametic; homogametic
D)epistatic; pleiotropic
E)epistatic; heterogametic

Question 12

Red-green color blindness is X-linked recessive.A woman with normal color vision has a father who is color blind.The woman has a child with a man with normal color vision.Which phenotype is NOT expected?

A)A color-blind female
B)A color-blind male
C)A noncolor-blind female
D)A noncolor-blind male

Question 13

What is the apparent purpose for X inactivation in humans and other mammals?

A)It allows for the levels of expression of genes on the X chromosome to be similar in males and females.
B)It allows for the levels of expression of genes on the autosomes to be similar to the levels of genes on the X chromosome.
C)It suppresses the expression of genes on the Y chromosome in males.
D)It reduces the amount of nondisjunction during meiosis in females.
E)It enhances the level of pairing between the two X chromosomes during meiosis in females.

Question 14

An XXY chromosome constitution produces _____ development in humans and _____ development in diploid fruit flies.

A)female; female
B)male; male
C)female; male
D)male; female
E)male, intersex

Question 15

The Lyon hypothesis helps us to understand which phenomenon in mammals?

A)X-linked inheritance
B)Evolution of the Y chromosome
C)Dosage compensation between males and females
D)Development of male and female secondary sexual characteristics
E)Sex determination

Question 16

What is the expected outcome for a human embryo with the XXXY chromosome constitution?

A)It would likely develop into a female who will not respond to the hormone testosterone.
B)It would likely develop into a sterile male with reduced testes.
C)It will always abort early in development before birth.
D)It would likely develop into a tall female who may be slightly cognitively impaired.
E)It would likely develop into a fertile man with a completely normal male phenotype.

Question 17

In a germ-line cell from a female grasshopper (XX-XO sex determination system), when do the homologous X chromosomes segregate?

A)During mitosis
B)During meiosis
C)Immediately after fertilization
D)They do not segregate; gametes contain a copy of X and a copy of Y.
E)Both answers a and c are correct

Question 18

Normal males (XY)and Klinefelter males (XXY)both possess only one active X chromosome.Nonetheless there are clearly phenotypic differences between the two.What is the MOST reasonable explanation as to why such differences exist?

A)The Y chromosome has higher gene expression levels when two X chromosomes are present compared to one X.
B)The Y chromosome has lower gene expression levels when two X chromosomes are present compared to one X.
C)Some genes remain active on inactive X chromosomes, so XXY males would produce higher expression levels for these genes compared to XY males.
D)XXY males exhibit a higher rate of problems during mitotic divisions than XY males.
E)XXY males don't have a copy of the SRY gene.

Question 19

Which of the following human genotypes is associated with Klinefelter syndrome?

A)XXY
B)XXXY
C)XXXXY
D)All of the answers are correct.
E)None of the answers is correct.

Question 20

Which of the following statements about X inactivation in mammalian females is FALSE?

A)Females that are heterozygous for an X-linked gene have patches of cells that express one allele and patches of cells that express the other.
B)Some genes on the inactive X continue to be expressed after the chromosome is inactivated.
C)X inactivation is random as to which X is inactivated and takes place early in embryonic development.
D)In an individual with three X chromosomes, one of the three will become inactivated.
E)Once an X chromosome first becomes inactivated in a cell, that same X will remain inactivated in somatic cells that are descendants of this cell.

Question 21

A eukaryotic diploid cell from an organism with the XX-XO sex determination system has two pairs of autosomes and one X chromosome, shown below. What is the probability of a gamete from this individual that has the following genotype: alleles A and b, chromosome X?

A)1/2
B)1/4
C)1/6
D)1/8
E)1/16

Question 22

A eukaryotic diploid cell from an organism with the ZZ-ZW sex determination system has two pairs of autosomes and a pair of sex chromosomes, Z and W, shown below. What is the probability of a gamete from this individual that has the following genotype: alleles A and b, chromosome Z?

A)1/2
B)1/4
C)1/6
D)1/8
E)1/16

Question 23

How many Barr bodies (condensed X chromosomes)would you predict in an XXY male with Klinefelter syndrome?

A)One per somatic cell
B)Two per somatic cell
C)Three per somatic cell
D)None
E)Either two or three depending on the tissue type

Question 24

In the endangered African watchamakallit, the offspring of a true-breeding black parent and a true-breeding white parent are all gray.When the gray offspring are crossed among themselves, their offspring occur in a ratio of 1 black:2 gray:1 white.Upon close examination of the coats, each hair of a gray animal is gray.What is the mode of inheritance?

A)One gene pair with black dominant to white
B)One gene pair with codominance
C)One gene pair with incomplete dominance
D)Two gene pairs with recessive epistasis
E)Two gene pairs with duplicate genes

Question 25

The trait shown below is expressed only in males in the family.What is the BEST explanation for the inheritance of this trait?

A)Y-linked inheritance
B)Sex-linked (X-linked)recessive inheritance
C)Autosomal recessive inheritance
D)X-linked dominant inheritance
E)None of these explanations fit for this trait.

Question 26

A eukaryotic diploid cell from an organism with the ZZ-ZW sex determination system has two pairs of autosomes and a pair of sex chromosomes, Z and W, shown below. A diploid cell from this individual begins to go through meiosis.After the completion of meiosis I, it becomes two cells.One of these two cells now undergoes meiosis II.Which of the following is a possible normal combination of chromosomes in one of the subsequent two cells after the completion of meiosis II?

A)One chromosome with the A allele, one with the B allele, one Z, one W
B)One chromosome with the A allele, one with the a allele, one with the B allele, one with the b allele, one Z, one W
C)A pair of chromosomes with A alleles, a pair of chromosomes with B alleles, a pair of Z chromosomes
D)One chromosome with an a allele, one chromosome with a B allele, one W
E)None of these is possible.

Question 27

Women known to be heterozygous or carriers for the sex-linked recessive condition of hemophilia A were studied to determine the time required for their blood to clot.It was found that the time required for their blood to clot varied from individual to individual.The values obtained ranged from normal clotting at one extreme to clinical hemophilia at the other extreme.What is the most probable CORRECT explanation for these findings?

A)Some women had only one X chromosome, and it is inactive.
B)Some women had three copies of the X chromosome which allowed them to make extra amounts of gene products for their X-linked genes.
C)The women with normal clotting times probably had a mother with hemophilia while those with abnormal clotting times probably had fathers with hemophilia.
D)Random X inactivation probably results in individuals with different proportions of cells in their bodies expressing the normal allele at the hemophilia locus.
E)In women with abnormal clotting times, there was probably an epistatic interaction between an allele on the X chromosome and an allele on an autosomal gene that reduced the expression of the X-linked gene.

Question 28

A eukaryotic diploid cell from an organism with the ZZ-ZW sex determination system has two pairs of autosomes and a pair of sex chromosomes, Z and W, shown below. From what type of individual is this cell?

A)Male
B)Female
C)Hermaphrodite
D)Homogametic
E)Pseudoautosomal

Question 29

A woman has normal vision although her maternal grandfather (her mother's father)had red-green color blindness, a sex-linked recessive trait.Her maternal grandmother and the woman's own father are assumed to not possess a copy of the mutant allele.The woman marries a man with normal vision although his father was color blind.What is the probability that the first child of this couple will be color blind?

A)1/2
B)1/4
C)1/8
D)1/16
E)1/12

Question 30

If a male bird that is heterozygous for a recessive Z-linked mutation is crossed to a wild type female, what proportion of the progeny will be mutant males?

A)0%
B)100%
C)75%
D)50%
E)25%

Question 31

A eukaryotic diploid cell from an organism with the XX-XO sex determination system has two pairs of autosomes and one X chromosome, shown below. A diploid cell from this individual begins to go through meiosis.After the completion of meiosis I, it becomes two cells.One of these two cells now undergoes meiosis II.Which of the following is a possible normal combination of chromosomes in one of the subsequent two cells after the completion of meiosis II?

A)One chromosome with the A allele, one with the B allele, and two X chromosomes
B)One chromosome with the A allele, one with the a allele, one with B allele, one with b allele, and two X chromosomes
C)One chromosome with the A allele, one chromosome with the B allele
D)One chromosome with the a allele, one chromosome with the B allele, one X chromosome
E)One chromosome with the A allele and one chromosome with the B allele AND one chromosome with the a allele, one chromosome with the B allele, and one X chromosome are BOTH possible.

Question 32

A woman is phenotypically normal, but her father had the sex-linked recessive condition of red-green color blindness.If she has children with a man with normal vision, what is the probability that their first child will have normal vision and their second child will be color blind?

A)1/16
B)3/8
C)3/16
D)3/6
E)8/27

Question 33

Familial vitamin-D-resistant rickets is an X-linked dominant condition in humans.If a man is afflicted with this condition and his wife is normal, it is expected that among their children, all the daughters would be affected and all the sons would be normal.In families where the husband is affected and the wife is normal, this is almost always the outcome among their children when such families have been studied.Very rarely an unexpected result occurs in such families where a boy is born with the disorder.If the chromosomes of such unusual boys are examined, what might be expected to be found?

A)Some of the boys are XYY.
B)Some of the boys are XY but have lost the SRY gene from their Y chromosome.
C)Some of the boys are YY.
D)Some of the boys are XXY.
E)Some of the boys are XXX.

Question 34

In humans there is a genetic disorder that results from a dominant mutation present in a gene located in the pseudoautosomal region of the Y chromosome and on the X chromosome.Which of the following statements is CORRECT?

A)All affected men marrying normal women will have no affected daughters.
B)All affected women marrying normal men will have affected daughters and no affected sons.
C)All affected men marrying normal women will have affected daughters, but all the sons will be normal.
D)All affected women marrying nomal men will have only normal sons and daughters.
E)None of the statements is correct.

Question 35

Interactions among the human ABO blood group alleles involve _____ and _____.

A)codominance; complete dominance
B)codominance; incomplete dominance
C)complete dominance; incomplete dominance
D)epistasis; complementation
E)continuous variation; environmental variation

Question 36

If a female Drosophila that is heterozygous for a recessive X-linked mutation is crossed to a wild-type male, what proportion of female progeny will have the mutant phenotype?

A)100%
B)0%
C)33%
D)25%

Question 37

Joan is phenotypically normal but had a child with the autosomal recessive disease cystic fibrosis (CF)from a previous marriage.Joan's father has hemophila A, a sex-linked recessive condition where the blood fails to clot properly.Her father has survived due to recent treatment advances.Joan now intends to marry Bill, who is also phenotypically normal but who has a sister, Jill, with CF.Bill's parents are phenotypically normal, and there is no history of hemophilia A in his family.Assume that Joan and Bill do marry and have a child.What is the probability that this child will have CF, but will not have hemophilia A ? (Hint: This problem requires that you utilize concepts from Chapter 3 as well as Chapter 4.)

A)1/8
B)1/12
C)1/24
D)3/32
E)5/32

Question 38

The R locus determines flower color in a new plant species.Plants that are genotype RR have red flowers, and plants that are rr have white flowers.However, Rr plants have pink flowers.What type of inheritance does this demonstrate for flower color in these plants?

A)Complete dominance
B)Incomplete dominance
C)Codominance
D)Complementation
E)Lethal alleles

Question 39

A eukaryotic diploid cell from an organism with the XX-XO sex determination system has two pairs of autosomes and one X chromosome, shown below. From what type of individual is this cell?

A)Male
B)Female
C)Hermaphrodite
D)Pseudoautosmal
E)Intersex

Question 40

A eukaryotic diploid cell from an organism with the ZZ-ZW sex determination system has two pairs of autosomes and a pair of sex chromosomes, Z and W, shown below. Assume A and B are dominant alleles.If this individual were crossed to an individual of genotype Aa Bb, what is the probability of a female offspring with the two dominant traits given by alleles A and B?

A)1/8
B)1/16
C)9/16
D)9/32
E)3/32

Question 41

A mother with blood type AB has a child with blood type B.Give all possible blood types for the father of this child.

A)O
B)B, AB
C)A, AB
D)A, B, O
E)A, B, AB, O

Question 42

In rabbits, an allelic series helps to determine coat color: C (full color), c^ch (chinchilla; gray color), c^h (Himalayan; white with black extremities), and c (albino; all white).The C allele is dominant to all others, c^ch is dominant to c^h and c, c^h is dominant to c, and c is recessive to all the other alleles.This dominance hierarchy can be summarized as C > c^ch > c^h > c.Indicate the phenotypic ratios expected in rabbits with the cross c^chc^h × c^hc.

A)1 full color:1 chinchilla
B)1 full color:1 Himalayan
C)1 chinchilla:1 Himalayan
D)3 full color:1 chinchilla
E)2 full color:1 Himalayan:1 albino

Question 43

In humans, blood types A and B are codominant to each other and each is dominant to O.What blood types are possible among the offspring of a couple of blood types AB and A?

A)A, B, AB, and O
B)A, B, and AB only
C)A and B only
D)A, B, and O only
E)A and AB only

Question 44

A mother of blood type A gives birth to a child with blood type O.Which of the following could NOT be the blood type of the father?

A)A
B)B
C)O
D)AB
E)Any of the above is a possible blood type of the father.

Question 45

In rabbits, an allelic series helps to determine coat color: C (full color), c^ch (chinchilla; gray color), c^h (Himalayan; white with black extremities), and c (albino; all white).The C allele is dominant to all others, c^ch is dominant to c^h and c, c^h is dominant to c, and c is recessive to all the other alleles.This dominance hierarchy can be summarized as C > c^ch > c^h > c.Indicate the phenotypic ratios expected in rabbits with the cross Cc × c^hc.

A)1 full color:1 chinchilla
B)1 full color:1 Himalayan
C)1 chinchilla:1 Himalayan
D)3 full color:1 chinchilla
E)2 full color:1 Himalayan:1 albino

Question 46

In rabbits, an allelic series helps to determine coat color: C (full color), c^ch (chinchilla; gray color), c^h (Himalayan; white with black extremities), and c (albino; all white).The C allele is dominant to all others, c^ch is dominant to c^h and c, c^h is dominant to c, and c is recessive to all the other alleles.This dominance hierarchy can be summarized as C > c^ch > c^h > c.Indicate the phenotypic ratios expected in rabbits with the cross Cc^h × c^hc.

A)1 full color:1 chinchilla
B)1 full color:1 Himalayan
C)1 chinchilla:1 Himalayan
D)3 full color:1 chinchilla
E)2 full color:1 Himalayan:1 albino

Question 47

A mother with blood type A has a child with blood type AB.Give all possible blood types for the father of this child.

A)O
B)B, AB
C)A, AB
D)A, B, O
E)A, B, AB, O

Question 48

Suppose that extra fingers and toes are caused by a recessive trait, but it appears in only 60% of homozygous recessive individuals.Two heterozygotes conceive a child.What is the probability that this child will have extra fingers and toes?

A)0)05
B)0)10
C)0)15
D)0)25
E)0)33

Question 49

A blood-type B woman is married to a man whose blood type is unknown.They have three children whose blood types are B, O, and AB.What is the husband's genotype?

A)I^AI^A
B)I^AI^O (I^O = i)
C)I^BI^O
D)I^BI^B
E)I^OI^O

Question 50

In rabbits, an allelic series helps to determine coat color: C (full color), c^ch (chinchilla; gray color), c^h (Himalayan; white with black extremities), and c (albino; all white).The C allele is dominant to all others, c^ch is dominant to c^h and c, c^h is dominant to c, and c is recessive to all the other alleles.This dominance hierarchy can be summarized as C > c^ch > c^h > c.Indicate the phenotypic ratios expected in rabbits with the cross Cc^h × cc.

A)1 full color:1 chinchilla
B)1 full color:1 Himalayan
C)1 chinchilla:1 Himalayan
D)3 full color:1 chinchilla
E)2 full color:1 Himalayan:1 albino

Question 51

A mother with blood type B has a child with blood type O.Give all possible blood types for the father of this child.

A)O
B)B, AB
C)A, AB
D)A, B, O
E)A, B, AB, O

Question 52

You are studying a gene that controls ossicone (horn)length in giraffes.The wild-type long-ossicone allele (L)is dominant to the mutant short-ossicone (l)allele.However the L allele is only 60% penetrant.You cross two heterozygous giraffes.What proportion of offspring would you expect to exhibit the long ossicone phenotype? Assume the penetrance of L applies equally to both homozygotes and heterozygotes.

A)0)40
B)0)45
C)0)55
D)0)60
E)0)75

Question 53

Polydactyly is the condition of having extra fingers or toes.Some polydactylous persons possess extra fingers or toes that are fully functional, whereas others possess only a small tag of extra skin.This is an example of:

A)variable expressivity.
B)complete dominance.
C)independent assortment.
D)complementation.
E)cytoplasmic inheritance.

Question 54

You are studying a gene that controls ossicone (horn)length in giraffes.The wild-type long-ossicone allele (L)is dominant to the mutant short-ossicone (l)allele.However, the L allele is only 60% penetrant.You cross two heterozygous giraffes.What proportion of offspring would you expect to exhibit the short ossicone phenotype? Assume the penetrance of L applies equally to both homozygotes and heterozygotes.

A)0)25
B)0)40
C)0)45
D)0)55
E)0)60

Question 55

Crossing two yellow mice results in 2/3 yellow offspring and 1/3 nonyellow offspring.What percentage of offspring would you expect to be nonyellow if you crossed two nonyellow mice?

A)25%
B)33%
C)66%
D)75%
E)100%

Question 56

In rabbits, an allelic series helps to determine coat color: C (full color), c^ch (chinchilla; gray color), c^h (Himalayan; white with black extremities), and c (albino; all white).The C allele is dominant to all others, c^ch is dominant to c^h and c, c^h is dominant to c, and c is recessive to all the other alleles.This dominance hierarchy can be summarized as C > c^ch > c^h > c.Indicate the phenotypic ratios expected in rabbits with the cross Cc^ch × Cc^h.

A)1 full color:1 chinchilla
B)1 full color:1 Himalayan
C)1 chinchilla:1 Himalayan
D)3 full color:1 chinchilla
E)2 full color:1 Himalayan:1 albino

Question 57

A mother with blood type A has a child with blood type A.Give all possible blood types for the father of this child.

A)O
B)B, AB
C)A, AB
D)A, B, O
E)A, B, AB, O

Question 58

You are studying body color in an African spider and have found that it is controlled by a single gene with four alleles: B (brown), b^r (red), b^g (green), and b^y (yellow).B is dominant to all the other alleles, and b^y is recessive to all the other alleles.The b^g allele is dominant to b^y but recessive to b^r.You cross a pure-breeding brown spider with a pure-breeding green spider.Predict the phenotype of the progeny.

A)Half brown, half green
B)Three-fourths brown, one-fourth green
C)All brown
D)All green
E)All yellow

Question 59

Achondroplasia is a common cause of dwarfism in humans.All individuals with achondroplasia are thought to be heterozygous at the locus that controls this trait.When two individuals with achondroplasia mate, the offspring occur in a ratio of 2 achondroplasia:1 normal.What is the MOST likely explanation for these observations?

A)Achondroplasia is incompletely dominant to the normal condition.
B)Achondroplasia is codominant to the normal condition.
C)The allele that causes achondroplasia is a dominant lethal allele.
D)The allele that causes achondroplasia is a recessive lethal allele.
E)The allele that causes achondroplasia is a late-onset lethal allele.

Question 60

You are studying body color in an African spider and have found that it is controlled by a single autosomal gene with four alleles: B (brown), b^r (red), b^g (green), and b^y (yellow).B is dominant to all the other alleles, and b^y is recessive to all the other alleles.The b^g allele is dominant to b^y but recessive to b^r.You cross a pure-breeding brown spider with a pure-breeding green spider.Predict the genotype of the progeny.

A)B/b^g
B)B^r/b^g
C)b^r/b^y
D)b^y/b^g
E)B/b^y

Question 61

In chickens, comb shape is determined by genes at two loci (R, r and P, p).A walnut comb is produced when at least one dominant gene R is present at one locus and at least one dominant gene P is present at a second locus (genotype R_ P_).A rose comb is produced when at least one dominant gene is present at the first locus and two recessive genes are present at the second locus (genotype R_ pp).A pea comb is produced when two recessive genes are present at the first locus and at least one dominant gene is present at the second (genotype rr P_).If two recessive genes are present at the first and the second locus (rr pp), a single comb is produced.Give genotypes for comb shape of the parents in the following cross: Walnut crossed with single produces one walnut, one rose, one pea, and one single offspring.

A)RR PP × rr pp
B)RR Pp × rr pp
C)Rr PP × rr pp
D)Rr Pp × rr pp
E)Rr pp × rr pp

Question 62

In chickens, comb shape is determined by genes at two loci (R, r and P, p).A walnut comb is produced when at least one dominant gene R is present at one locus and at least one dominant gene P is present at a second locus (genotype R_ P_).A rose comb is produced when at least one dominant gene is present at the first locus and two recessive genes are present at the second locus (genotype R_ pp).A pea comb is produced when two recessive genes are present at the first locus and at least one dominant gene is present at the second (genotype rr P_).If two recessive genes are present at the first and the second locus (rr pp), a single comb is produced.Give genotypes for comb shape of the parents in the following cross: rose crossed with pea produces 20 walnut offspring.

A)RR pp × rr PP
B)Rr pp × rr Pp
C)Rr pp × rr PP
D)RR pp × rr Pp
E)Rr pp × Rr Pp

Question 63

Two loci control body color in beetles.In a cross between a black beetle and a white beetle you obtain a ratio of 9 black to 7 white beetles.What kind of gene interaction is this?

A)Recessive epistasis
B)Dominant epistasis
C)Duplicate recessive epistasis
D)Duplicate dominant epistasis
E)Dominant and recessive epistasis

Question 64

Hair color is determined in Labrador retrievers by alleles at the B and E loci.A dominant allele B encodes black pigment, whereas a recessive allele b encodes brown pigment.Alleles at a second locus affect the deposition of the pigment in the shaft of the hair; dominant allele E allows dark pigment (black or brown)to be deposited, whereas recessive allele e prevents the deposition of dark pigment, causing the hair to be yellow.A black female Labrador retriever was mated with a yellow male.Half of the puppies were black and half were yellow.If the genotype of the black female parent was Bb Ee, then what was the genotype of the other parent?

A)bb ee
B)bb EE
C)Bb ee
D)BB ee
E)BB EE

Question 65

Coat color is determined by two loci in large cats.Two pink panthers fall in love and produce a large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16 white.What is the genotype of the white progeny?

A)A_ B_
B)A_ bb
C)aa B_
D)aa bb
E)A_ B_ and A_ bb

Question 66

A woman is deaf because of being homozygous recessive at an autosomal locus.She marries a deaf man who is also homozygous recessive at an autosomal locus.They have two children who have normal hearing.Assuming that this couple is the biological parents of these children, how is this situation MOST reasonably explained?

A)Imprinting-the allele from the father is active, and the allele from the mother is inactive in the children.
B)Epistasis-two genes are involved with the alleles at one locus suppressing gene activity at a second locus.
C)Sex-limited-the trait is only expressed in one gender but not in both.
D)Imprinting-the allele from the mother is active, and the allele from the father is inactive in the children.
E)Complementation-the parents are homozygous recessive at different loci, and the children are heterozygous at both.

Question 67

In purple people eaters, purple is dominant to white.A true-breeding white mutant is mated with a different true-breeding white mutant.All of the F₁ are purple.When the purple F₁ offspring mate with each other, their offspring occur in the ratio of 9 purple:7 white.Which phenomenon explains the purple F₁ offspring?

A)Recessive epistasis
B)Dominant epistasis
C)Complementation
D)Mutation
E)Suppression

Question 68

Hair color is determined in Labrador retrievers by alleles at the B and E loci.A dominant allele B encodes black pigment, whereas a recessive allele b encodes brown pigment.Alleles at a second locus affect the deposition of the pigment in the shaft of the hair; dominant allele E allows dark pigment (black or brown)to be deposited, whereas recessive allele e prevents the deposition of dark pigment, causing the hair to be yellow.What type of gene interaction does this represent?

A)Recessive epistasis
B)Dominant epistasis
C)Duplicate recessive epistasis
D)Duplicate dominant epistasis
E)Dominant and recessive epistasis

Question 69

In chickens, comb shape is determined by genes at two loci (R, r and P, p).A walnut comb is produced when at least one dominant gene R is present at one locus and at least one dominant gene P is present at a second locus (genotype R_ P_).A rose comb is produced when at least one dominant gene is present at the first locus and two recessive genes are present at the second locus (genotype R_ pp).A pea comb is produced when two recessive genes are present at the first locus and at least one dominant gene is present at the second (genotype rr P_).If two recessive genes are present at the first and the second locus (rr pp), a single comb is produced.Give genotypes for comb shape of the parents in the following cross: pea crossed with single produces one single offspring.

A)rr PP × rr pp
B)RR Pp × rr pp
C)Rr PP × rr pp
D)Rr Pp × rr pp
E)rr Pp × rr pp

Question 70

Suppose that the "fabulous" phenotype is controlled by two genes, A and B, as shown in the diagram below.Allele A produces enough enzyme 1 to convert "plain" to "smashing." Allele a produces no enzyme 1.Allele B produces enough enzyme 2 to convert "smashing" to "fabulous." Allele b produces no enzyme 2.The A and B genes are both autosomal and assort independently. What will be the phenotype(s)of the F₁ offspring of a true-breeding "fabulous" father and a true-breeding "plain" mother (aa bb)?

A)All "plain"
B)All "smashing"
C)All "fabulous"
D)"Plain" females and "fabulous" males
E)"Fabulous" females and "smashing" males

Question 71

Coat color is determined by two loci in large cats.Two pink panthers fall in love and produce a large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16 white.What kind of gene interaction is this?

A)Recessive epistasis
B)Dominant epistasis
C)Duplicate recessive epistasis
D)Duplicate dominant epistasis
E)Dominant and recessive epistasis

Question 72

In chickens, comb shape is determined by genes at two loci (R, r and P, p).A walnut comb is produced when at least one dominant gene R is present at one locus and at least one dominant gene P is present at a second locus (genotype R_ P_).A rose comb is produced when at least one dominant gene is present at the first locus and two recessive genes are present at the second locus (genotype R_ pp).A pea comb is produced when two recessive genes are present at the first locus and at least one dominant gene is present at the second (genotype rr P_).If two recessive genes are present at the first and the second locus (rr pp), a single comb is produced.Give genotypes for comb shape of the parents in the following cross: rose crossed with pea produces two walnut, one single, and one pea offspring.

A)RR pp × rr PP
B)Rr pp × rr Pp
C)Rr pp × rr PP
D)RR pp × rr Pp
E)Rr pp × Rr Pp

Question 73

Coat color is determined by two loci in large cats.Two pink panthers fall in love and produce a large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16 white.What might be the genotype of the pink progeny?

A)A_ B_
B)A_ bb
C)aa B_
D)aa bb
E)A_ B_ and A_ bb

Question 74

In chickens, comb shape is determined by genes at two loci (R, r and P, p).A walnut comb is produced when at least one dominant gene R is present at one locus and at least one dominant gene P is present at a second locus (genotype R_ P_).A rose comb is produced when at least one dominant gene is present at the first locus and two recessive genes are present at the second locus (genotype R_ pp).A pea comb is produced when two recessive genes are present at the first locus and at least one dominant gene is present at the second (genotype rr P_).If two recessive genes are present at the first and the second locus (rr pp), a single comb is produced.Give genotypes for comb shape of the parents in the following cross: rose crossed with single produces 31 rose offspring.

A)RR PP × rr pp
B)RR pp × rr pp
C)Rr PP × rr pp
D)Rr Pp × rr pp
E)Rr pp × rr pp

Question 75

In order to determine if mutations from different organisms that exhibit the same phenotype are allelic, which test would you perform?

A)Testcross
B)Epistasis test
C)Complementation test
D)Allelic series test
E)Biochemical test

Question 76

In the yawncat (a rare hypothetical animal), the dominant allele R causes solid tail color, and the recessive allele r results in white spots on a colored background.The black coat color allele B is dominant to the brown allele b, but these genes can only be expressed if the animal has an mm genotype at a third gene locus.Animals that are M_ are yellow regardless of which allele from the B locus is present.A mating between a solid yellow-tailed male yawncat and a solid brown-tailed female yawncat produces 16 offspring with the following tail phenotypes: six solid yellow, two spotted yellow, three solid black, one spotted black, three solid brown, and one spotted brown.What is the probability of the next offspring from these same two parents having a spotted brown tail?

A)1/2
B)3/16
C)1/4
D)1/16
E)9/16

Question 77

In the yawncat (a rare hypothetical animal), the dominant allele R causes solid tail color, and the recessive allele r results in white spots on a colored background.The black coat color allele B is dominant to the brown allele b, but these genes can only be expressed if the animal has an mm genotype at a third gene locus.Animals that are M_ are yellow regardless of which allele from the B locus is present.A mating between a solid yellow-tailed male yawncat and a solid brown-tailed female yawncat produces 16 offspring with the following tail phenotypes: six solid yellow, two spotted yellow, three solid black, one spotted black, three solid brown, and one spotted brown.What is the MOST likely genotype of the male parent?

A)MM BB RR
B)MM Bb RR
C)Mm Bb RR
D)Mm BB Rr
E)Mm Bb Rr

Question 78

Coat color is determined by two loci in large cats.Two pink panthers fall in love and produce a large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16 white.What might be the genotype of the black progeny?

A)A_ B_
B)AA Bb
C)aa B_
D)aa bb
E)A_ B_ and A_ bb

Question 79

A 13:3 ratio is obtained from the cross Aa Bb ×Aa Bb.What phenotypic ratio is expected if an Aa Bb individual is testcrossed (Aa Bb × aa bb)?

A)1:1:1:1
B)9:7
C)2:1
D)3:1
E)13:3

Question 80

In the yawncat (a rare hypothetical animal), the dominant allele R causes solid tail color, and the recessive allele r results in white spots on a colored background.The black coat color allele B is dominant to the brown allele b, but these genes can only be expressed if the animal has an mm genotype at a third gene locus.Animals that are M_ are yellow regardless of which allele from the B locus is present.A mating between a solid yellow-tailed male yawncat and a solid brown-tailed female yawncat produces 16 offspring with the following tail phenotypes: six solid yellow, two spotted yellow, three solid black, one spotted black, three solid brown, and one spotted brown.What is the MOST likely genotype of the female parent?

A)mm bb rr
B)Mm bb rr
C)mm Bb rr
D)mm bb Rr
E)mm Bb Rr