Deck 17: Inheritance of Sex Chromosomes, Linked Genes, and Organelles

Question 1

The X chromosome is unlike the autosomes in that the X chromosome in a male always comes from the father.

Answer 1

False

Question 2

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

Answer 2

True

Question 3

Given equal probabilities of the birth of a boy or girl, if a group of four siblings consists of all girls, what is the probability that the next birth is a boy?

A)4/5
B)3/4
C)2/3
D)1/2

Answer 3

D

Question 4

In most species, the sex chromosomes have identical genes along their length.

Question 5

Pairing of homologous chromosomes at metaphase of meiosis I appears to be critical for proper alignment, crossing over, and subsequent separation. This pairing is facilitated by sharing of sequence homology. If X and Y chromosomes are so different, how can they achieve the necessary pairing?

A)They share short homologies at their respective tips.
B)They use a unique sex-linked mechanism not present in other pairs.
C)They do not need to pair because they are not a homologous pair.
D)A special function of the spindle apparatus forces X and Y together.

Question 6

The total number of chromosomes differs between human males and females.

Question 7

In the human X and Y chromosomes, an obligatory crossover in meiosis helps ensure proper:

A)gene dosage.
B)segregation.
C)independent assortment.
D)random distribution.

Question 8

The gene density of the X chromosome is BEST described by which of the following statements?

A)The gene density of the X chromosome is like that of the gene density in the Y chromosome.
B)The gene density of the X chromosome is like that of the gene density in an autosome.
C)It is unique.
D)None of the answer options is correct.

Question 9

The secondary sex ratio of newborns in the United States is 105 males:100 females. Why doesn't this match the 1:1 predicted primary sex ratio?

A)because males and females have different survival rates between conception and birth
B)because there are often errors in chromosomal segregation at meiosis I
C)because defects in essential sex-determining hormones change the sex of zygotes after fertilization
D)because there is sometimes spontaneous chromosome duplication of the X or Y after development begins

Question 10

Why didn't Mendel discover the nature of sex chromosomes in his pea plants?

A)Peas, and most other plants, do not have sex chromosomes.
B)He focused only on the flowers and the seeds.
C)The 3:1 and 9:3:3:1 ratios of offspring did not fit the pattern of sex determination in peas.
D)The sex chromosomes were too difficult to see with his rudimentary microscope.

Question 11

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

A)The chromosome number is doubled during this phase of meiosis.
B)In females, the two X chromosomes remain together.
C)In males, the X chromosome is segregated from the Y chromosome.
D)The centromeres of the chromosomes divide.
E)Homologous chromosomes move as one unit.

Question 12

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

A)X and Y chromosomes demonstrate independent assortment.
B)X and Y chromosomes demonstrate segregation.
C)X and Y chromosomes pair all along their length.
D)X and Y chromosomes together determine sex.
E)All of these choices are correct.

Question 13

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

Question 14

Which of the following BEST describes the behavior of the human X and Y chromosomes during meiosis?

A)The X and Y chromosomes have no regions of homology and therefore do not pair during meiosis.
B)The X and Y chromosomes have regions of homology that allow them to pair during meiosis.
C)Although the X and Y chromosomes pair during meiosis, crossover does not occur.
D)Crossover occurs when the X and Y chromosomes pair during meiosis.
E)None of the other answer options is correct.

Question 15

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

Question 16

Given equal probabilities of the birth of a boy or girl, what is the probability that a group of three siblings includes exactly two boys? Exactly three boys? Two or more boys?

A)1/8; 1/8; 1/4
B)1/4; 1/4; 1/2
C)3/8; 1/8; 1/2
D)1/2; 1/8; 5/8

Question 17

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

Question 18

The human X chromosome carries approximately 1000 genes. The Y chromosome contains only about 50 genes. How can males survive with only these 50 genes in the Y chromosome?

A)The Y is paired with a functional X chromosome, which has all the genes.
B)The genes in the X chromosome are not required for survival.
C)In males, the missing genes are found in autosomal chromosomes.
D)Most of the 1000 genes in the X chromosome are only required for females.

Question 19

Given equal probabilities of the birth of a boy or girl, if a pair of siblings contains at least one boy, what is the probability that both children are boys?

A)1/2
B)1/3
C)3/4
D)2/3

Question 20

In what ways do human X and Y chromosomes differ from one another?

A)The X chromosome is larger than the Y chromosome.
B)The X chromosome has about 1000 genes and the Y chromosome only about 50.
C)The X chromosome is found only in females, while the Y chromosome is found only in males.
D)The X and Y chromosomes have no regions in common and do not pair during meiosis.

Question 21

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

Question 22

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)1/2; 1/4; 1/4
B)1/2; 1/2; 1/2
C)1/2; 1/2; 1/4
D)1; 1/2; 1/2
E)1; 1/4; 1/2

Question 23

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/A₂; A₃
B)A₁/A₃; A₂
C)A₂/A₃; A₁
D)A₁/A₃; A₃
E)A₁/A₃; A₁

Question 24

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)M and H
B)H and K
C)H and L
D)K and L
E)K and Q

Question 25

Which one of the following statements regarding the human Y chromosome is TRUE?

A)The Y chromosome is large compared to the X chromosome.
B)The gene density of the Y chromosome is similar to that of autosomes.
C)The Y chromosome contains approximately 50 genes.
D)The Y chromosome has a similar gene content as the X chromosome.
E)None of the answer options is correct.

Question 26

For an X-linked gene, which of the following genotype options is possible?

A)A female or a male can be homozygous for this gene.
B)A female or a male can be heterozygous for this gene.
C)A female can be homozygous or heterozygous for this gene.
D)A male can be homozygous for this gene.
E)A male can be heterozygous for this gene.

Question 27

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.

Question 28

A cross involving an autosomal gene versus a sex-linked gene would differ in that:

A)both parents would have two copies of a sex-linked gene.
B)a Punnett square could not be utilized for solving a cross involving a sex-linked gene.
C)the phenotype outcomes of females compared to males could be different.
D)only autosomal genes observe the law of segregation.
E)recombination or crossing over could not take place between sex chromosomes.

Question 29

Considering a rare X-linked recessive trait, which of the following statements is/are TRUE?

A)An unaffected woman whose father was affected is expected to have unaffected sons.
B)An unaffected father is expected to have unaffected daughters.
C)An affected mother is expected to have affected sons.
D)An affected father is expected to have affected daughters.
E)Both parents have to be affected in order to have affected daughters.

Question 30

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/A₂; A₃
B)A₁/A₃; A₂
C)A₂/A₃; A₁
D)A₁/A₃; A₃
E)A₁/A₃; A₁

Question 31

A woman at a train station sees a family with five boys. The occurrence of five boys in this family is likely the result of a mutation in one of the X chromosomes of the mother that impacts the survival of female embryos in the womb.

Question 32

Segregation of X and Y chromosomes in males happens during anaphase II of meiosis.

Question 33

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.

Question 34

Genes located along the X chromosome:

A)have a full set of complementary alleles in the Y chromosome.
B)are called X-linked genes.
C)are contributed solely by the female parent.
D)are always recessive to genes located in the Y chromosome.

Question 35

Which of the following statements regarding sex ratios is TRUE?

A)Sex ratios remain constant over time.
B)The ratio of males to females at birth is skewed slightly toward females.
C)Fewer females tend to survive to reproductive age, and the sex ratio of males to females during adolescence is about 1:1.
D)The ratio of males to females at age 90 or older to about 1.5:1.
E)Sex ratios are dynamic and can change over time; the ratio of males to females at birth may be different from that during adolescence and adulthood.

Question 36

X-linked inheritance does not follow the inheritance patterns of which of Mendel's discoveries?

A)dominance
B)segregation
C)independent assortment
D)equivalence of reciprocal crosses
E)None of the answer options is correct.

Question 37

Which one of the following statements about the sex chromosomes is FALSE?

A)The X chromosome has a gene density similar to most autosomes.
B)In contrast to the approximately 1000 genes in the X chromosome, the Y chromosome contains only about 50 genes.
C)The relative size and gene content of the X and Y chromosomes is very similar across all animal species.
D)Crossing over between the X and Y chromosomes occurs in very small regions of homology at the tips of the chromosomes.
E)Crossing over between the X and Y chromosomes allows the sex chromosomes to align correctly during metaphase I and separate from each other during anaphase I.

Question 38

Which one of the following statements about segregation of the sex chromosomes is FALSE?

A)In human males, segregation of the X chromosome from the Y chromosome occurs during anaphase I of meiosis.
B)In humans, half of the fertilized eggs are expected to be male and half are expected to be female; this 1:1 ratio is characteristic of Mendelian segregation.
C)The secondary sex ratio of males to females at birth usually shows a slight excess of males.
D)In humans, the sex at each birth is not a random process because there are often large families with either all girls or all boys.

Question 39

When X-linked traits are recessive, males who express the trait:

A)receive the recessive allele from their mothers.
B)receive the recessive allele from their fathers.
C)must receive recessive alleles from both parents.
D)carry the recessive allele in their X chromosome.
E)receive the recessive allele from their mothers and carry the recessive allele in their X chromosomes.

Question 40

Which of the following statements regarding both the X and Y chromosomes is TRUE?

A)All organisms on Earthwhether insects, birds, mammals, and so onhave both X and Y chromosomes.
B)If an organism of any species is male, it must possess a Y chromosome.
C)The Y chromosome of any species is always smaller than the X chromosome.
D)The X and Y chromosomes are similar across all species, given the evolutionary relationship between these chromosomes.
E)None of the other answer options is correct.

Question 41

In Drosophila, the red-eye allele for eye color exhibits complete dominance over the recessive white-eye allele. In some of Thomas Hunt Morgan's initial experiments, he crossed red-eyed female flies with white-eyed males. When he then crossed the F₁ red-eyed heterozygous females with red-eyed males, Morgan found that half of the male progeny were white-eyed. What is the MOST likely explanation of this result?

A)The gene responsible for eye color is on the Y chromosome.
B)The gene responsible for eye color is on the X chromosome.
C)The gene responsible for eye color is on an autosome.
D)Chemical factors secreted by males changed the color of the eye.
E)Chemical factors secreted by males mutated the eye color gene.

Question 42

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/A₂; A₃
B)A₁/A₃; A₂
C)A₂/A₃; A₁
D)A₂/A₃; A₂
E)A₂/A₃; A₃

Question 43

If you tracked an individual X chromosome from a male to his first generation offspring, then to his second-generation offspring, what pattern would you see?

A)His X chromosome would be found only in his daughters and granddaughters.
B)His X chromosome would be found only in his sons and grandsons.
C)His X chromosome would be found only in his daughters and grandsons.
D)His X chromosome would be found only in his daughters, then in both his granddaughters and grandsons.
E)His X chromosome would be found only in his sons, then in both his granddaughters and grandsons.

Question 44

The pedigree shown here pertains to a trait due to a rare, X-linked recessive mutation. Individual 1 has an affected brother and husband, but the genotypes and phenotypes of individuals 1, 3, and 4 are unknown. What is the probability that individual 1 is heterozygous? What is the probability that individual 3 is affected? What is the probability that individual 4 is affected?

A)1/2; 1/4; 1/4
B)1/2; 0; 1/2
C)1; 1/2; 1/4
D)1; 1/2; 1/2
E)1; 1/4; 1/4

Question 45

Mutations in the Y chromosome are inherited by males in every generation, whereas mutations in the X chromosome exhibit a crisscross inheritance pattern. Why is this?

A)The Y chromosome determines maleness.
B)The Y chromosome shares a high homology with the X chromosome.
C)All the genes in the Y chromosome have complete linkage.
D)The mutations are advantageous therefore they are preserved.

Question 46

In one set of experiments, Calvin Bridges crossed white-eyed female fruit flies with red-eyed males. Some of the offspring were white-eyed females. These individuals, he demonstrated, had the genotype _____, which occurred because of _____ during meiosis.

A)XXX; nondisjunction
B)XXO; independent assortment
C)XXY; random segregation
D)XXO; nondisjunction
E)XXY; nondisjunction

Question 47

Which of the following statements is TRUE of human sex chromosomes?

A)There are sex-linked genes that females have that males do not have.
B)There are sex-linked genes that males have that females do not have.
C)All sperm contain the Y chromosome, whereas all eggs contain the X chromosome.
D)The contribution from the mother determines the sex of the child.
E)A healthy child with two sex chromosomes of the same kind can be male.

Question 48

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)1; 0; 0
C)0; 0; 1
D)0; 1; 0
E)0; 0; 0

Question 49

Nondisjunction of the sex chromosomes can be used to demonstrate that:

A)the X chromosome determines femaleness.
B)the Y chromosome determines maleness.
C)the sex chromosomes are different.
D)genes are present in chromosomes.
E)None of the answer options is correct.

Question 50

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.

Question 51

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)affected fathers do not have affected daughters.
B)affected mothers do not have affected sons.
C)affected fathers do not have affected sons.
D)affected mothers do not have affected daughters.
E)the two possibilities cannot be distinguished.

Question 52

A female fruit fly that is heterozygous for the white-eye mutation has red-eyed sons and white-eyed sons in equal proportions:

A)only when mated with a red-eyed male.
B)only when mated with a white-eyed male.
C)only when mated with a heterozygous male.
D)regardless of the genotype of the male.

Question 53

An X-linked ichthyosis is a recessive form of a family of skin diseases caused by a hereditary deficiency of the steroid sulfatase (STS) enzyme. A woman heterozygous for this mutation mates with the phenotypically normal man and produces an XXY son who suffers from the disorder. What kind of nondisjunction can explain this result?

A)nondisjunction in meiosis I in the mother
B)nondisjunction in meiosis I in the father
C)nondisjunction in meiosis II in the mother
D)nondisjunction in meiosis II in the father

Question 54

A recessive X-linked trait can be found in:

A)females.
B)males.

Question 55

Recessive alleles in the X chromosome are expressed in males because:

A)males are more sensitive to mutations than females.
B)the X chromosome is dominant in males.
C)the Y chromosome does not contain the wild-type allele.
D)All of these choices are correct.

Question 56

Nondisjunction of X chromosomes that occurs in the first meiotic division results in eggs with the following genotypes:

A)XX.
B)XY.
C)O)
D)X)

Question 57

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/A₂; A₃
B)A₁/A₃; A₂
C)A₂/A₃; A₁
D)A₁/A₃; A₃
E)A₁/A₃; A₁

Question 58

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

Question 59

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)M and H
B)H and K
C)H and L
D)K and L
E)K and Q

Question 60

Experimental demonstration that genes are present in chromosomes was inferred from the:

A)segregation of the X and Y chromosomes.
B)disjunction of the X and Y chromosomes.
C)nondisjunction of the X and Y chromosomes.
D)appearance of white-eyed males.
E)None of the other answer options is correct.

Question 61

When X-linked traits are recessive, females will express the traits only if they are _____ for the recessive allele.

A)homozygous
B)heterozygous

Question 62

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

A)carrier
B)harborer
C)homozygote
D)unaffected female
E)messenger

Question 63

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?

A)A₁/A₂
B)A₁/A₃
C)A₂/A₃
D)A₁
E)A₃

Question 64

A wild-type fruit fly:

A)exhibits a mutant phenotype.
B)exhibits the most common phenotype in the population.
C)exhibits a phenotype that marks it as a party animal.
D)expresses a large proportion of homozygous recessive alleles.
E)will most likely have white eyes.

Question 65

In a male fruit fly, the white-eye gene is carried in the Y chromosome.

Question 66

A normal woman with a color-blind brother:

A)is herself heterozygous for the gene causing color blindness.
B)has a 50% chance of being heterozygous for the gene causing color blindness.
C)has a 25% chance of being heterozygous for the gene causing color blindness.
D)has a 10% chance of being heterozygous for the gene causing color blindness.
E)cannot carry the gene causing color blindness.

Question 67

Morgan's discovery of a white-eyed male was important because the mutant gene proved to be in:

A)the X chromosome.
B)the Y chromosome.
C)an autosome.
D)the mitochondrial DNA.

Question 68

In fruit flies, daughters of a cross between a white-eyed male and a red-eyed female always have red eyes.

Question 69

Two examples of X-linked inheritance in humans are:

A)blue eyes and red hair.
B)sickle-cell anemia and alpha-1-antitrypsin deficiency.
C)type II diabetes and high blood pressure.
D)red-green color blindness and hemophilia.
E)None of the answer options is correct.

Question 70

Red-green color blindness is a sex-linked recessive trait in humans. If a carrier female (heterozygous for the trait) mated with an affected male, what would be the expected outcome(s)?

A)None of the offspring would be color blind.
B)None of the daughters would be color blind.
C)Half of the daughters would be color blind.
D)All of the sons would be color blind.
E)Half of the daughters would be color blind, and all of the sons would be color blind.

Question 71

If a female fruit fly is heterozygous and carries one allele for white eyes and one allele for red eyes, her mutant allele and her nonmutant allele will segregate during meiosis I.

Question 72

In 1910, Thomas Hunt Morgan discovered a white-eyed fruit fly in his population of wild-type, red-eyed flies. This white-eye phenotype occurs:

A)in all male and female fruit flies every other generation.
B)only in female fruit flies.
C)only in male fruit flies.
D)only in one-half of female offspring from a white-eyed male and a red-eyed homozygous female.
E)in one-half of the male offspring from a red-eyed heterozygous female and a white-eyed male.

Question 73

The presence of a nonmutant gene in one chromosome often masks the effect of a mutant allele for that same gene in its homologous chromosome.

Question 74

In fruit flies, sons of a cross between a white-eyed male and a red-eyed female always have red eyes.

Question 75

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 sons?

A)A₁/A₂
B)A₁/A₃
C)A₂
D)A₁
E)A₃

Question 76

In fruit flies, an X chromosome carrying the allele for white eyes is transferred from a male to a female of the next generation and in the next generation is transmitted back to the male again. This is called:

A)Morgan inheritance.
B)crisscross inheritance.
C)incomplete penetrance.
D)epistasis.

Question 77

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

A)Both parents have two copies of a sex-linked gene.
B)A Punnett square cannot be utilized for illustrating the possible outcomes of a cross involving a sex-linked gene.
C)The phenotype outcomes of female offspring compared to males can be different.
D)Only autosomal genes observe the law of segregation.
E)Recombination or crossing over cannot take place between sex chromosomes.

Question 78

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) along with DNA types that might (or might not) correspond to their offspring. What are the possible phenotypes of daughters from this mating?

A)M and H
B)H and K
C)K and L
D)H and L
E)M and L

Question 79

In animals with sex chromosomes, males inherit their X chromosome from their _____ and transmit it to their _____.

A)mothers; daughters
B)mothers; sons
C)fathers; daughters
D)fathers; sons
E)mothers; sons and daughters

Question 80

Thomas Hunt Morgan crossed a white-eyed male with red-eyed females in a parental generation and then brother-sister mated the F₁ offspring and examined their F₂ progeny. Morgan observed all of the following in his crosses. Which of these observations is NOT expected of simple Mendelian inheritance of a recessive allele?

A)the F₁ generation flies all had red eyes
B)white eyes reappeared in the F₂ generation
C)white eyes appeared only in males in the F₂ generation
D)white eyes appeared only in females in the F₂ generation
E)white eyes appeared in both males and females in the F₂ generation