Deck 11: Genes, Chromosomes, and Human Genetics

Question 1

Which of the following best describes sex-linked genes?

A)They are located on the X chromosome.
B)They are linked to the sex-determining gene.
C)They are expressed differently based on the sex of an individual.
D)They are determinants of the sex of an individual.

Answer 1

A

Question 2

If two genes are located on different chromosomes, what percentage of the offspring should have a recombinant phenotype?

A)about 75%
B)about 50%
C)about 25%
D)about 10%

Answer 2

B

Question 3

In Drosophila melanogaster the allele for long wings is dominant over the allele for vestigial wings, and the allele for a grey body is dominant over the allele for a black body. A testcross was done to check for genetic linkage between the genes for these traits, with the following results for the offspring: 410 flies with long wings and a black body
105 flies with long wings and a grey body
390 flies with vestigial wings and a grey body
95 flies with vestigial wings and a black body
Which of the following best represents the map distance between the genes for these two traits?

A)10.0 map units
B)20.0 map units
C)40.0 map units
D)100.0 map units

Answer 3

B

Question 4

Suppose two genes a and b are 7.4 map units from each other, and that genes b and c are 5.7 map units from each other. You do a cross to determine the map distance between a and

A)2.0 map units
B)11.1 map units
C)14.8 map units
C) Which result would indicate that c lies between a and b?
D)15.0 map units

Question 5

Which process is generally the cause for the production of recombinant offspring for two genes on the same chromosome?

A)movement of transposable elements
B)crossing-over between homologous chromosomes
C)gene duplication
D)exon shuffling

Question 6

Consider the following genetic study involving two autosomal genes. One of these, eye colour, has the dominant allele (R) for red eye colour and the recessive allele (r) for yellow eye colour. The other has the dominant allele (T) leading to paws with thumbs, while the recessive allele (t) codes for paws without thumbs. Presuming no linkage between the genes, what should be the phenotype ratio of the offspring produced by a testcross (RrTt ? rrtt)?

A)1 red-eyed with thumbs: 1 yellow-eyed without thumbs
B)3 red-eyed with thumbs: 1 yellow-eyed without thumbs
C)1 red-eyed with thumbs: 1 yellow-eyed with thumbs: 1 red-eyed without thumbs: 1 yellow-eyed without thumbs
D)9 red-eyed with thumbs: 3 yellow-eyed with thumbs: 3 red-eyed without thumbs: 1 yellow-eyed without thumbs

Question 7

Under which condition would you expect the SRY gene to be switched on?

A)if no X chromosome is present
B)if an X chromosome is present
C)if a Y chromosome is present
D)if two X chromosomes are present

Question 8

What is caused by the human genetic condition called progeria?

A)muscular and mental deterioration shortly after puberty
B)socially inappropriate vocal outbursts and muscular twitches
C)premature aging that typically leads to death in the early teenage years
D)pattern baldness as early as age 20

Question 9

Which phrase best defines what is meant by gene linkage?

A)genes that affect two different traits and that lead to a 9:3:3:1 phenotype ratio in a dihybrid cross
B)genes that do not sort independently due to their being physically near each other on the same chromosome
C)different alleles of the same gene
D)genes whose effects combine to affect a single characteristic

Question 10

What do genetic map units represent?

A)relative positions of genes with respect to each other
B)the chromosome on which a given gene is located
C)the actual DNA sequence of a gene
D)absolute physical distances between genes

Question 11

Which of the following traits determines recombination frequency between two linked genes?

A)the relative sizes of the two chromosomes that each have one of the two genes
B)the distance between the two genes on a single chromosome
C)the distance between the two chromosomes that each have one of the two genes
D)the overall size of the chromosome on which the genes are located

Question 12

If two genes on the same chromosome are located 10 map units from each other, what percentage of the offspring should have a recombinant phenotype?

A)about 10%
B)about 25%
C)about 50%
D)about 75%

Question 13

Who developed the concept of mapping genes on chromosomes when he was an undergraduate student?

A)Thomas Morgan
B)Francis Crick
C)James Watson
D)Alfred Sturtevant

Question 14

What are the two major types of chromosomes in many eukaryotic organisms?

A)sex and non-sex
B)XY and ZZ
C)sex and autosomes
D)autosomes and ZZ

Question 15

Which scientist was responsible for the characterization of linked genes?

A)Gregor Mendel
B)James Watson
C)Thomas Morgan
D)Alfred Sturtevant

Question 16

Suppose that in Drosophila melanogaster, the allele for red eyes is dominant over the allele for purple eyes, and the allele for a grey body is dominant over the allele for a black body. Also suppose that a testcross was done to check for genetic linkage between the genes for these traits, with the following results for the offspring: 478 flies with red eyes and a black body
27 flies with red eyes and a grey body
462 flies with purple eyes and a grey body
33 flies with purple eyes and a black body
Which of the following best represents the map distance between the genes for these two traits?

A)50.0 map units
B)30.0 map units
C)27.0 map units
D)6.0 map units

Question 17

Consider the following genetic study involving two autosomal genes. One of these, eye colour, has the dominant allele (R) for red eye colour and the recessive allele (r) for yellow eye colour. The other has the dominant allele (T) leading to paws with thumbs, while the recessive allele (t) codes for paws without thumbs. If these genes are not linked, what should be the phenotype ratio of the offspring produced by a testcross (RrTt ? rrtt)?

A)1 red-eyed with thumbs: 1 yellow-eyed without thumbs
B)9 red-eyed with thumbs: 3 yellow-eyed with thumbs: 3 red-eyed without thumbs: 1 yellow-eyed without thumbs
C)3 red-eyed with thumbs: 1 yellow-eyed without thumbs
D)1 red-eyed with thumbs: 1 yellow-eyed with thumbs: 1 red-eyed without thumbs: 1 yellow-eyed without thumbs

Question 18

In humans, which condition does sex determination generally depend upon?

A)on the environment in the womb
B)on the number of X chromosomes present
C)on whether or not the Y chromosome is present
D)on whether or not the X chromosome is present

Question 19

Suppose that in studies of genes on the same chromosome, you find the following recombination frequencies: a 40% frequency for a and b, a 30% frequency for a and c, and a 10% frequency for b and

A)alternative alleles that are not physically possible because the numbers do not add up
B)linked genes that are not physically possible because the numbers do not add up
C)Which phrase best describes the relationship between genes a, b, and c?
C)linked genes
D)different alleles of the same gene

Question 20

Suppose an individual is born with both an X and a Y chromosome, but the Y chromosome has a mutation that eliminates the function of the SRY gene. How would this person appear phenotypically?

A)hermaphrodite
B)male
C)male, but with some female features
D)female

Question 21

Suppose that you examine a vial of 100 flies that are all offspring from a single genetic cross. Also suppose that the only females you see present are red-eyed, but the males you see present are both red-eyed and white-eyed. The allele for red eye colour (X^w+) is dominant over the allele for white eye colour (X^w). Which of the following describes the genotypes of the parents?

A)X^w+X^w; X^w+Y
B)X^wX^w; X^w+Y
C)X^w+X^w; X^wY
D)X^w+X^w+; X^w+Y

Question 22

From which studies did the discovery of sex-linked genes and the production of the first chromosome map arise?

A)from the studies of pea plants
B)from the studies of humans
C)from the studies of fruit flies
D)from the studies of corn

Question 23

Suppose that you examine a vial of 100 flies that are all offspring from a single genetic cross. Suppose also that you see that all the females present are red-eyed and all the males present are white-eyed. The allele for red eye colour (X^w+) is dominant over the allele for white eye colour (X^w). Which of the following describes the genotypes of the parents?

A)X^w+X^w; X^wY
B)X^wX^w; X^w+Y
C)X^w+X^w+; X^wY
D)X^w+X^w; X^w+Y

Question 24

Suppose that a woman with normal blood clotting mates with a man who also has normal blood clotting, and that their first child is a boy who has X-linked hemophilia. Which statement best predicts the outcomes of their mating?

A)All of the children will have hemophilia.
B)None of the children should have hemophilia.
C)All of the boys and half of the girls will have hemophilia.
D)Half of the boys and none of the girls will have hemophilia.

Question 25

In the figure, what type of change in the chromosomes is depicted?

A)a reciprocal translocation
B)a duplication
C)an inversion
D)a deletion

Question 26

Which of the following processes is most likely responsible for many mammals having multiple hemoglobin genes?

A)a reciprocal translocation
B)a duplication
C)an inversion
D)a deletion

Question 27

Suppose that a woman with normal blood clotting mates with a man who has X-linked hemophilia. Given that the woman is heterozygous for the trait, which statement best predicts the outcomes of their mating?

A)All of the children will have hemophilia.
B)Half of the boys and none of the girls will have hemophilia.
C)Half of the boys and half of the girls will have hemophilia.
D)None of the children should have hemophilia.

Question 28

In the figure, what type of change in the chromosomes is depicted?

A)an inversion
B)a deletion
C)a reciprocal translocation
D)a duplication

Question 29

Suppose that crossing-over during meiosis occurs within a region where one of the homologous chromosomes has an inversion with respect to the other homolog. Which chromosomal alterations would you expect to find in the gametes produced by this organism?
a.balanced translocations
b.translocations
c.both duplications and deletions
d.deletions

Question 30

Which phrase best describes chromosomal nondisjunction?

A)failure of homologous pairs or sister chromatids to separate during meiosis
B)failure of sister chromatids to pair during mitosis
C)improper pairing of nonhomologous chromosomes during meiosis
D)failure of homologous pairs to separate during meiosis

Question 31

Suppose that a man and woman have a son with a rare genetic disorder known to be X-linked. There is no occurrence of the disorder on the woman's side of the family, but the man's brother has it, as does her father. What is the probability that the son's defective allele came from the man?

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

Question 32

Suppose that you examine a vial of 100 flies that are all offspring from a single genetic cross. Also suppose that you find both red-eyed females and white-eyed females, as well as both red-eyed males and white-eyed males. The allele for red eye colour (X^w+) is dominant over the allele for white eye colour (X^w). Which of the following describes the genotypes of the parents?

A)X^w+X^w+; X^wY
B)X^w+X^w; X^wY
C)X^w+X^w; X^w+Y
D)X^wX^w; X^w+Y

Question 33

How is the distinctive fur pattern of a calico cat produced?

A)by X-chromosome inactivation
B)by hormones
C)by Y-chromosome inactivation
D)by epistasis

Question 34

Which of the following kinds of information can be revealed through a family pedigree analysis?

A)the chromosomal location of disease-related allele
B)sex linkage
C)the DNA sequence of disease-related allele
D)the source of the original mutation in the disease-related allele

Question 35

What is the name of the human disorder in which a deletion from chromosome 5 typically leads to severe mental retardation and a malformed larynx?

A)triple-X syndrome
B)cri-du-chat
C)Down syndrome
D)Turner syndrome

Question 36

In the figure, what type of change in the chromosomes is depicted?

A)an inversion
B)a deletion
C)a reciprocal translocation
D)a duplication

Question 37

Which of the following describes an individual who is a carrier of a genetically inherited disease?

A)The individual has the disease, and any offspring will have the disease.
B)The individual does not have the disease, but must have a parent with the disease.
C)The individual does not have the disease, but may have offspring with the disease.
D)The individual has the disease, and must have a parent with the disease.

Question 38

In the figure, what type of change in the chromosomes is depicted?

A)a deletion
B)a reciprocal translocation
C)an inversion
D)a duplication

Question 39

Suppose that you examine a vial of 100 flies that are all offspring from a single genetic cross, and you find only red-eyed females and red-eyed males present. You allow these flies to interbreed, and in the next generation you find all the females are red-eyed, but you find both red-eyed and white-eyed males. The allele for red eye colour (X^w+) is dominant over the allele for white eye colour (X^w). Which of the following best describes the genotypes of the original parents?

A)X^w+X^w+; X^wY
B)X^w+X^w; X^w+Y
C)X^w+X^w; X^wY
D)X^wX^w; X^w+Y

Question 40

Which sex chromosome combinations would you expect to find in a male calico cat?

A)XX
B)XXY
C)XYY
D)XY

Question 41

Which term refers to an individual with extra or missing copies of some of their chromosomes?

A)haploid
B)aneuploid
C)polyploid
D)euploid

Question 42

About 4% of people of northern European descent are carriers for an autosomal recessive genetic disorder in which a defective membrane transport protein leads to abnormal chloride levels in extracellular fluids. What is the name of this disorder?

A)Duchenne muscular dystrophy
B)cystic fibrosis
C)achondroplasia
D)sickle cell anemia

Question 43

Which autosomal dominant genetic trait associated with a gene on human chromosome 4 leads to a type of dwarfing due to defective cartilage formation?

A)achondroplasia
B)sickle cell anemia
C)Duchenne muscular dystrophy
D)phenylketonuria

Question 44

A mutation in the human gene for a fibroblast growth factor receptor (FGFR) is related to cartilage formation. Which disorder does this mutation appear to be responsible for?

A)phenylketonuria
B)sickle cell anemia
C)achondroplasia
D)Duchenne muscular dystrophy

Question 45

A woman with which of the following human conditions would exhibit normal physical features?

A)triple-X syndrome
B)Turner syndrome
C)Down syndrome
D)cri-du-chat

Question 46

Most hospitals routinely test all newborns for an autosomal recessive disorder in which an enzyme in amino acid metabolism is NOT produced. In this disorder, lack of the enzyme leads to a buildup of compounds that damage brain tissue, possibly leading to mental retardation, unless a restricted diet is followed. What is the name of this disorder?

A)Duchenne muscular dystrophy
B)achondroplasia
C)sickle cell anemia
D)phenylketonuria

Question 47

Suppose that you are a genetic counsellor, and a man and woman come to you with concerns that if they have a child together, it could have sickle cell anemia. Also suppose that genetic tests reveal that the man and woman are both carriers for sickle cell anemia. Which of the following is the best advice you could give them?

A)They should not have any concerns, because no child that they produce will have sickle cell anemia.
B)Each child that they produce will have a 25% chance of having sickle cell anemia.
C)No child that they produce should have sickle cell anemia, but each of their children's offspring will have a 50% chance of being a carrier.
D)Each child that they produce will have a 50% chance of having sickle cell anemia, and the other 50% will be carriers.

Question 48

About 10 to 15% of African Americans are carriers of an autosomal recessive genetic disorder in which a defective version of hemoglobin is produced. What is the name of this disorder?

A)phenylketonuria
B)Duchenne muscular dystrophy
C)sickle cell anemia
D)achondroplasia

Question 49

Why do carriers for sickle cell anemia have a genetic advantage in some situations over those who are not carriers?

A)because carriers have the ability to carry more oxygen in their blood
B)because carriers have increased resistance to malaria
C)because carriers have hyperactive immune systems
D)because carriers have lower blood pressure

Question 50

How does the age of the mother seem to correlate with the incidence of genetic birth defects?

A)Defect incidence sometimes increases and sometimes decreases with increasing age.
B)Defect incidence decreases with increasing age.
C)Defect incidence increases with increasing age.
D)Defect incidence has no correlation to age.

Question 51

Which of the following disorders has X-linked recessive inheritance?

A)sickle cell anemia
B)phenylketonuria
C)Duchenne muscular dystrophy
D)achondroplasia

Question 52

Which genetic condition is revealed in the karyotype display?

A)cri-du-chat
B)triple-X syndrome
C)Turner syndrome
D)Down syndrome

Question 53

Suppose you are a genetic counsellor, and a man and woman come to you with concerns that if they have a child together, it could have cystic fibrosis. Also suppose that genetic tests reveal that the woman is a carrier for cystic fibrosis but the man is NOT. Which of the following is the best advice you could give them?

A)Each child that they produce will have a 50% chance of having cystic fibrosis, and the other 50% will be carriers.
B)They should not have any concerns, because no child that they produce should have cystic fibrosis.
C)No child that they produce should have cystic fibrosis, but each of their children will have a 50% chance of being a carrier.
D)Each of their offspring will have cystic fibrosis.

Question 54

About half of all flowering plant species, including many important crop plants, belong to which category of chromosomes?

A)euploids
B)haploids
C)aneuploids
D)polyploids

Question 55

Suppose you are a genetic counsellor, and a man and woman come to you with concerns that if they have a child together, it could have hemophilia. Also suppose that the man has an X-linked recessive form of hemophilia, but the woman does NOT, and that genetic tests reveal the woman is NOT a carrier for hemophilia. Which of the following is the best advice you could give them?

A)Each child that they produce will have a 50% chance of having hemophilia.
B)None of their offspring should have hemophilia, but each of their female offspring will be carriers for hemophilia.
C)Each of their male offspring will have a 50% chance of having hemophilia; and while their female offspring should not have hemophilia, they will each have a 50% chance of being carriers.
D)Each of their male offspring will have hemophilia, and each of their female offspring will have a 50% chance of having hemophilia.

Question 56

Which of the following occurs in cells of human individuals with three or more X chromosomes?
a.Two X chromosomes remain active, and all others are inactivated.
b.One X chromosome remains active, and the rest are inactivated.
c.All of the X chromosomes remain active.
d.Two X chromosomes remain active in females and one remains active in males; the rest are inactivated.

Question 57

Which of the following is most likely to happen to a human polyploid?

A)survival until the mid-30s age range
B)death around the age of one year
C)natural abortion
D)survival until the early teenage years

Question 58

Suppose that you are a genetic counsellor, and a couple comes to you with concerns that if they have a child together, it could have hemophilia. Suppose also that neither one of them has hemophilia, but the woman's biological father did have an X-linked recessive form of hemophilia. Which of the following is the best advice you could give them?

A)Each of their male offspring will have hemophilia, and each of their female offspring will have a 50% chance of having hemophilia.
B)None of their offspring should have hemophilia, but each of their female offspring will be carriers for hemophilia.
C)Each child that they produce will have a 50% chance of having hemophilia.
D)Each of their male offspring will have a 50% chance of having hemophilia, and while their female offspring should not have hemophilia, they will each have a 50% chance of being carriers.

Question 59

Which term refers to an individual with three or more copies of each of their chromosomes?

A)aneuploid
B)haploid
C)polyploid
D)euploid

Question 60

Suppose you are a genetic counsellor, and a man and woman come to you with concerns that if they have a child together, it could have hemophilia. Also suppose that the woman has an X-linked recessive form of hemophilia, but the man does NOT. Which of the following is the best advice you could give them?

A)Each of their male offspring will have hemophilia, and each of their female offspring will have a 50% chance of having hemophilia.
B)Each of their male offspring will have a 50% chance of having hemophilia; and while their female offspring should not have hemophilia, they will each have a 50% chance of being carriers.
C)None of their offspring should have hemophilia, but each of their female offspring will be carriers for hemophilia.
D)Each of their male offspring will have hemophilia; and while their female offspring should not have hemophilia, they will all be carriers.

Question 61

Which genes are subject to cytoplasmic inheritance?

A)genes found in mitochondria and chloroplasts
B)genes found in viruses
C)genes found in bacteria
D)genes found in sex chromosomes

Question 62

How are mitochondria inherited in most multicellular organisms?

A)only from the father
B)from the mother for females and from the father for males
C)randomly from either the father or the mother
D)only from the mother

Question 63

What typically leads to cancers associated with mammalian insulin growth factor 2 (Igf2)?

A)duplication
B)translocation
C)X-inactivation
D)loss of imprinting

Question 64

Suppose your cousin finds out that she is a carrier for phenylketonuria. Also suppose that her husband's biological mother has phenylketonuria. She asks you to explain what this could mean if she and her husband have children, and she asks you what, if anything, could be done to best protect any child that they have. What would you tell her?

Question 65

Prader-Willi syndrome and Angelman syndrome are both caused by the same genetic deletion on human chromosome 15, but they have very different phenotypes. Whether one or the other syndrome occurs depends upon which parent provided the chromosome with the deletion. What is this pattern of inheritance an example of?

A)sex-linked inheritance
B)cytoplasmic inheritance
C)genomic imprinting
D)uniparental inheritance

Question 66

Suppose that you have discovered a new mutant in Drosophila melanogaster. What kinds of genetic crosses should you do to determine if the allele causing the mutation is inherited as an autosomal dominant trait, an autosomal recessive trait, or a sex-linked trait?

Question 67

Prenatal diagnosis techniques such as amniocentesis and chorionic villus sampling involve the removal of cells that were produced by an embryo. What are these cells then used for?

A)to test for the presence of mutant alleles or chromosomal alterations
B)to treat diseases
C)for implantation to produce pregnancy
D)to develop embryonic stem cells

Question 68

Suppose that you are working in a research lab on the organism Drosophila melanogaster and you have been given the job of determining the relative positions of three linked genes for your undergraduate research project. A graduate student in the lab tells you that gene a is 5.0 centimorgans from gene b, and that gene c is 2.7 centimorgans from gene
b. What should you do to finish mapping these three genes? What results are likely to occur, and how would you interpret such results?

Question 69

Match each of the following genetic conditions with its mode of inheritance. A mode of inheritance may be used once, more than once, or not at all.
a.autosomal recessive
b.autosomal dominant
c.X-linked recessive
d.aneuploidy
e.genomic imprinting
Down syndrome

Question 70

Match each of the following genetic conditions with its mode of inheritance. A mode of inheritance may be used once, more than once, or not at all.
a.autosomal recessive
b.autosomal dominant
c.X-linked recessive
d.aneuploidy
e.genomic imprinting
hemophilia A

Question 71

Match each of the following genetic conditions with its mode of inheritance. A mode of inheritance may be used once, more than once, or not at all.
a.autosomal recessive
b.autosomal dominant
c.X-linked recessive
d.aneuploidy
e.genomic imprinting
phenylketonuria

Question 72

Match each of the following genetic conditions with its mode of inheritance. A mode of inheritance may be used once, more than once, or not at all.
a.autosomal recessive
b.autosomal dominant
c.X-linked recessive
d.aneuploidy
e.genomic imprinting
red-green colour blindness

Question 73

Match each of the following genetic conditions with its mode of inheritance. A mode of inheritance may be used once, more than once, or not at all.
a.autosomal recessive
b.autosomal dominant
c.X-linked recessive
d.aneuploidy
e.genomic imprinting
sickle cell anemia

Question 74

Match each of the following genetic conditions with its mode of inheritance. A mode of inheritance may be used once, more than once, or not at all.
a.autosomal recessive
b.autosomal dominant
c.X-linked recessive
d.aneuploidy
e.genomic imprinting
cystic fibrosis

Question 75

Match each of the following genetic conditions with its mode of inheritance. A mode of inheritance may be used once, more than once, or not at all.
a.autosomal recessive
b.autosomal dominant
c.X-linked recessive
d.aneuploidy
e.genomic imprinting
achondroplasia

Question 76

Match each of the following genetic conditions with its mode of inheritance. A mode of inheritance may be used once, more than once, or not at all.
a.autosomal recessive
b.autosomal dominant
c.X-linked recessive
d.aneuploidy
e.genomic imprinting
Huntington disease

Question 77

Which term refers to an expression of only one allele of a gene and the silencing of the other allele, all based on which parent contributed each allele?

A)genomic imprinting
B)uniparental inheritance
C)sex-linked inheritance
D)cytoplasmic inheritance

Question 78

Which of the following is the molecular mechanism responsible for genomic imprinting?

A)methylation
B)ligation
C)mutation
D)deletion

Question 79

Match each of the following genetic conditions with its mode of inheritance. A mode of inheritance may be used once, more than once, or not at all.
a.autosomal recessive
b.autosomal dominant
c.X-linked recessive
d.aneuploidy
e.genomic imprinting
Angelman syndrome