Deck 7: Chromosomes and Human Genetics

Question 1

Which of the following must be true for a woman who is heterozygous for a given gene?

A)She must be heterozygous for all genes.
B)All of her eggs will contain both of the alleles for that gene.
C)All of her eggs will contain one allele or the other,but not both alleles.
D)She carries a rare mutation.

Answer 1

C

Question 2

A karyotype of an individual with mild mental retardation shows three copies of the X chromosome.If this individual decides to have children,how is her chromosomal abnormality likely to affect her offspring?

A)All of her children will inherit an extra copy of the X chromosome.
B)Any female children have a 75 percent chance of inheriting an extra copy of an X chromosome.
C)She will be unable to produce male children.
D)Half of her eggs will contain an extra copy of the X chromosome.

Answer 2

D

Question 3

Two copies of the same gene on a single chromosome would indicate a(n)________ had occurred.

A)deletion
B)duplication
C)inversion
D)translocation

Answer 3

B

Question 4

Chromosomes that are NOT involved in determining gender are known as

A)autosomes.
B)sex chromosomes.
C)homologues.
D)linked.

Question 5

Humans have ________ pairs of homologous chromosomes.

A)46
B)23
C)22
D)44

Question 6

The gender of a human child is determined by the

A)loci.
B)egg.
C)autosomes.
D)sperm.

Question 7

One chromosomal abnormality that is usually fatal is

A)a mutation in a gene.
B)an exchange of material between homologous chromosomes.
C)extra copies of sex chromosomes.
D)the addition of an extra autosomal chromosome.

Question 8

Which of the following would explain two chromosomes in an individual cell that contain some,but not all,of the same genes at the same loci?

A)Both of the chromosomes are paternal.
B)Both of the chromosomes are maternal.
C)The chromosomes are from a common ancestor.
D)A chromosomal alteration has occurred.

Question 9

In humans,X-linked genetic diseases

A)are associated with autosomes.
B)tend to be expressed more in females than males.
C)only affect males.
D)tend to be expressed more in males than in females.

Question 10

What information is NOT visible in a karyotype?

A)the individual's sex
B)the number of autosomes
C)whether the individual carries genetic mutations
D)whether deletions have occurred

Question 11

Which of the following statements about homologous chromosomes is true?

A)There are 46 pairs in humans.
B)They contain the same genes in the same locations.
C)They contain identical alleles in the same location.
D)They are also known as sex chromosomes.

Question 12

During cell division a piece of a chromosome breaks off and reattaches to the same chromosome,but the piece is now in reverse order.How would this abnormality affect the chromosome?

A)An extra copy of the chromosome will be made to ensure normal function.
B)The inverted section will be deleted to prevent problems.
C)The chromosome will take on a circular configuration.
D)Genes in the section that was inverted could lose normal function.

Question 13

In a karyotype of a male,which of the following would indicate an abnormality?

A)one X chromosome and one Y chromosome
B)three copies of chromosome 22
C)22 pairs of autosomes
D)a total of 46 chromosomes

Question 14

A karyotype from an adult male indicates a chromosomal abnormality,which does not affect his health.Which of the following abnormalities is most likely seen?

A)three copies of the X chromosome
B)no copies of chromosome 2
C)a translocation between chromosome 14 and chromosome 15
D)a deletion on chromosome 5

Question 15

Which of the following genetic changes would NOT be passed from parent to child?

A)a mutation in a skin cell
B)the loss of a chromosome in a sperm cell
C)the addition of a chromosome in an egg cell
D)a translocation in a gamete

Question 16

A karyotype shows a chromosomal abnormality that does not change the length of any of the chromosomes.Which abnormality is indicated?

A)inversion
B)deletion
C)translocation
D)duplication

Question 17

In the pedigree shown,the individual indicated represents a(n)

A)healthy male.
B)healthy female.
C)affected male.
D)affected female.

Question 18

A ________ is a chart that shows genetic relationships within a family over several generations.

A)karyotype
B)pedigree
C)Punnett square
D)single-gene disorder map

Question 19

The karyotype shown is from a(n)

A)male.
B)female.
C)individual of undetermined sex.
D)individual with a genetic disorder.

Question 20

On chromosomes within an individual,there are ________ alleles for a given gene found on ________ chromosomes.

A)two;homologous
B)four;maternal
C)four;paternal
D)two;Y

Question 21

Which of the following statements would indicate a pedigree that shows the inheritance pattern of a recessive X-linked disease?

A)Most affected individuals are females.
B)Most affected individuals are males.
C)Males and females are affected equally.
D)The disease is seen in every generation.

Question 22

The gene for a certain sex-linked trait is found only on the Y chromosome.If the male parent carries this gene,which of the following statements about the inheritance of that trait is true?

A)The trait will be expressed in 100 percent of the female offspring.
B)The trait will be expressed in 50 percent of the female offspring.
C)The trait will be expressed in 100 percent of the male offspring.
D)The trait will be expressed in 50 percent of the male offspring.

Question 23

The pedigree shown diagrams an X-linked gene.The individual indicated is ________ for the gene.

A)heterozygous
B)homozygous
C)autosomal
D)There is not enough information to determine the answer.

Question 24

Why are X-linked recessive genetic disorders more commonly seen in males?

A)For an X-linked disorder to occur,an individual must receive one allele only found on the X chromosome and a second allele found only on the Y chromosome,which females do not have.
B)Females must receive two copies of the recessive allele to exhibit the disorder,but males need only one copy.
C)The alleles of sex-linked genes are carried only on the Y chromosome,which females do not have.
D)Females only have X chromosomes and genes on the X chromosome are not expressed.

Question 25

The genetic disorder followed through the pedigree shown is

A)recessive and X-linked.
B)recessive and autosomal.
C)dominant and X-linked.
D)dominant and autosomal.

Question 26

A carrier is an individual with a ________ genotype who does not express the recessive trait but can pass it along to offspring.

A)homozygous
B)heterozygous
C)recessive
D)dominant

Question 27

Most inherited human genetic disorders are inherited as ________ alleles.

A)dominant
B)recessive
C)homologous
D)sex-linked

Question 28

Both members of a couple are carriers for a recessive disease allele.If the couple has four children,which of the following statements must be true?

A)One of the children has the disease.
B)Two of the children have the disease.
C)All of the male children have the disease.
D)Fifty percent of the children could be carriers of the disease.

Question 29

Which of the following genotypes represents a human male?

A)XY
B)YY
C)XX
D)XO

Question 30

In which of the following situations would looking at a pedigree be most useful?

A)An adopted boy is admitted to the hospital with recurrent vomiting.
B)A young girl is born with diminished hearing and a cleft palate.
C)Six unrelated individuals with similar symptoms are admitted to the hospital in a one-week period.
D)Three young boys who are first cousins show symptoms of a neurological disorder.

Question 31

A female who is a carrier of the sex-linked gene A has the genotype

A)Aa.
B)AA.
C)aa.
D)XAXa.

Question 32

Because an individual with an XX genotype is a female,is an individual with an XO (no second sex chromosome)a male?

A)No,because the X always overrides the Y and makes that embryo female.
B)No,because the Y chromosome contains the gene that makes an embryo male.
C)Yes,because if there is only one X,the embryo cannot become female.
D)Yes,because all embryos start off as males.

Question 33

Autosomal dominant diseases are exhibited by anyone who carries at least one dominant allele for that gene.How is it that dominant lethal genes,such as the one that causes Huntington disease,can persist in a population?

A)The disease-causing allele can "hide" in the heterozygous condition.
B)The disease develops only under the influence of other genes.
C)These diseases usually take effect later in life after people have had children.
D)The environment plays a large role in determining whether the gene is expressed.

Question 34

If a father is affected by an X-linked condition and the mother is a carrier,what is the probability of their children being affected?

A)All sons will be affected.
B)Half of the sons will be affected.
C)All daughters will be affected.
D)Half of the sons will be carriers.

Question 35

A person is genetically XX and develops as a male.How can this be explained?

A)In humans,males are XX.
B)An error in karyotyping this individual must have occurred because XX individuals cannot develop into a male.
C)A piece of a Y chromosome has become attached to one of the X chromosomes.
D)The SRY gene was deleted in this individual.

Question 36

In humans,the "master sex switch" that determines whether an embryo will become a male is the

A)X chromosome.
B)locus.
C)SRY gene.
D)androgen switch.

Question 37

Most inherited human disorders are the result of

A)recessive mutations of genes located on autosomes.
B)dominant mutations of genes located on the X chromosome.
C)recessive mutations of genes located on the Y chromosome.
D)simultaneous mutations of the same gene on homologous chromosomes.

Question 38

An allele that appears more frequently in males is most likely

A)dominant.
B)nonhomologous.
C)autosomal.
D)sex-linked.

Question 39

Which of the following is true of the genetic cross shown in the figure?

A)All of their daughters will be carriers.
B)Their sons have a 50 percent chance of being carriers.
C)Their sons have a 50 percent chance of having the disorder.
D)Their daughters have a 50 percent chance of having the disorder.

Question 40

The X chromosome in humans is

A)found as a pair in females.
B)the only human sex chromosome.
C)present only in females.
D)always found in single copy.

Question 41

Which of the following information is available in a Punnett square showing the inheritance pattern for an autosomal recessive disorder?

A)percentage of males likely to be affected by the disorder
B)percentage of females likely to be affected by the disorder
C)percentage of all children likely to be affected by the disorder
D)number of children born to the two parents

Question 42

If a genetic disorder is caused by a dominant allele,individuals with which of the following genotypes would be affected by the disorder?

A)AA and aa
B)aa and Aa
C)AA and Aa
D)AA,Aa,and aa

Question 43

What characteristics of inheritance would allow you to distinguish whether a disorder is recessive autosomal,dominant autosomal,or sex-linked?

Question 44

Human males have one chromosome that females do not,known as the ________ chromosome.

Question 45

Among children with parents who are both carriers of Tay-Sachs,an autosomal recessive disorder,chances are that

A)75 percent will be carriers.
B)50 percent will die in a few years.
C)75 percent will not carry the recessive Tay-Sachs's allele.
D)50 percent will be carriers.

Question 46

The parents in the figure shown are carriers of a genetic disorder.Based on the Punnett square,the allele that causes the disorder must be

A)autosomal.
B)sex-linked.
C)dominant.
D)incompletely dominant.

Question 47

An individual who carries one copy of a recessive mutated allele and one normal copy is referred to as a genetic ________.

Question 48

Every gene in a human occupies a specific position or ________ in their chromosomes.

Question 49

If the male in generation II was affected,what would the pattern of inheritance most likely be?

A)X-linked recessive
B)X-linked dominant
C)autosomal recessive
D)autosomal dominant

Question 50

If two parents are heterozygous for an autosomal recessive disease,

A)they are both considered genetic carriers for the disease.
B)their children have no chance of inheriting the disease.
C)their children have a 50 percent chance of inheriting the disease.
D)all of their children will also be heterozygous.

Question 51

Sickle-cell disease is an inherited chronic blood disease caused by an autosomal recessive allele.Suppose a man who is homozygous recessive for the sickle-cell gene fathers a child by a woman who is a carrier for sickle-cell.What are the chances their children will exhibit the disease?

A)0 percent
B)25 percent
C)50 percent
D)75 percent

Question 52

Explain how two brothers might have different X chromosomes,but they must share identical Y chromosomes.

Question 53

Except for the sex chromosomes,all the chromosomes shown in a karyotype are numbered and are called ________.

Question 54

Would a karyotype for a human male be considered normal if it shows 45 autosomes and a single pair of sex chromosomes? Explain your reasoning.

Question 55

A parent who is a carrier for the recessive autosomal disorder B has the genotype ________.

Question 56

If a recessive allele causes a fatal disease that kills the affected individual before he or she can reproduce,why doesn't that allele quickly become extinct in the population?

A)Alleles are never lost from a population.
B)The homozygous dominant individuals protect the recessive allele in their genomes.
C)The recessive allele is carried in the genome of heterozygotes,who do not suffer from the disease.
D)The homozygous recessive individuals give their alleles to other individuals before they die from the disease.

Question 57

What information in a pedigree would indicate a condition is likely dominant?

A)Twenty-five percent of the individuals in the pedigree have the condition.
B)Two-thirds of the affected individuals are females.
C)None of the affected individuals have unaffected parents.
D)Most of the affected individuals are males.

Question 58

A man with a translocation in a chromosome that does not affect gene function may not realize he has a translocation until he attempts to have a child.Explain how a translocation that does not affect the individual may become problematic during reproduction.

Question 59

If an individual has two alleles at a given locus that are different,the individual is said to be ________ for the gene.

Question 60

An allele that "hides" in heterozygous carriers is called a ________ allele.

Question 61

Match each correct statement to the set of alleles listed below.
a.Bb
b.XaY
c.XAXa
d.bb
e.XAXA
f.BB
g.XAY
female carrier of a sex-linked disease

Question 62

If DNA testing reveals that you carry a single allele for a particular genetic disorder but you do not currently show symptoms of the disease,is it possible that you will develop the disease later in life? Explain.

Question 63

Why are dominant genetic disorders more rare than recessive disorders?

Question 64

Match each correct statement to the set of alleles listed below.
a.Bb
b.XaY
c.XAXa
d.bb
e.XAXA
f.BB
g.XAY
recessive homozygous for an autosomal gene

Question 65

Does the pedigree shown most likely represent a condition that is autosomal recessive,dominant,or sex-linked? Explain your reasoning.

Question 66

Match each correct statement to the set of alleles listed below.
a.Bb
b.XaY
c.XAXa
d.bb
e.XAXA
f.BB
g.XAY
heterozygous for an autosomal gene

Question 67

Match each correct statement to the set of alleles listed below.
a.Bb
b.XaY
c.XAXa
d.bb
e.XAXA
f.BB
g.XAY
male affected by recessive sex-linked disease

Question 68

Match each correct statement to the set of alleles listed below.
a.Bb
b.XaY
c.XAXa
d.bb
e.XAXA
f.BB
g.XAY
dominant homozygous for an autosomal gene