Deck 20: Chromosomes and Human Genetics

Question 1

DNA coding regions that affect the same trait are called

A) homologues.
B) alleles.
C) autosomes.
D) loci.
E) gametes.

Answer 1

B

Question 2

Closely linked genes nearly always end up

A) crossing over.
B) assorting independently.
C) in the same gamete.
D) segregated during meiosis.
E) inverted.

Answer 2

C

Question 3

Genes are

A) located on chromosomes.
B) inherited in the same way as chromosomes.
C) arranged in linear sequence on chromosomes.
D) may be exchanged between homologous chromosomes.
E) all of these.

Answer 3

E

Question 4

Which of the following statements is false?

A) Crossing over tends to reduce the frequency that two linked genes are inherited together.
B) Independent assortment of homologous chromosomes during meiosis increases variation.
C) Crossing over leads to variation.
D) An abnormal number or structure of chromosomes may influence the course of evolution.
E) The closer together genes are found on a chromosome, the greater the chance that crossing over will occur between them.

Question 5

Karyotyping is usually done using what kind of cells?

A) muscle
B) blood
C) cartilage
D) sex
E) epidermal

Question 6

The location of a gene on a chromosome is its

A) centromere.
B) locus.
C) autosome.
D) allele.
E) centriole.

Question 7

In karyotyping, individual chromosomes may be distinguished from others by

A) a comparison of chromosome lengths.
B) bands produced on chromosomes by differential staining.
C) the position of centromeres.
D) the relative lengths of the "arms."
E) all of these.

Question 8

A karyotype

A) compares one set of chromosomes to another.
B) is a visual display of chromosomes arranged according to size.
C) is a photograph of cells undergoing mitosis during anaphase.
D) of a normal human cell shows 48 chromosomes.
E) can reveal the genotype of an individual.

Question 9

Which of the following would be an exception to the principle of independent assortment?

A) dominance
B) recessiveness
C) incomplete dominance
D) pleiotropy
E) linkage

Question 10

Karyotype analysis

A) is a means of detecting and reducing mutagenic agents.
B) is a surgical technique that separates chromosomes that have failed to segregate properly during meiosis II.
C) can be used in prenatal diagnosis to detect chromosomal mutations and genetic disorders in embryos.
D) replaces defective alleles with normal ones.
E) is used in DNA analysis for paternity.

Question 11

Genes that are located on the same chromosome may

A) tend to be inherited together.
B) appear together in the gamete.
C) be linked.
D) be separated during crossing over.
E) all of these

Question 12

If two genes are almost always found in the same gamete,

A) they are located close together on the same chromosome.
B) they are located on nonhomologous chromosomes.
C) they are located far apart on the same chromosome.
D) they are found on the sex chromosome.
E) they are found on the autosome.

Question 13

The maximum life expectancy for a patient with cystic fibrosis is approximately

A) 15 years.
B) 20 years.
C) 25 years.
D) 30 years.
E) 50 years.

Question 14

Which chemical is used to arrest mitosis at metaphase?

A) Giemsa stain
B) acetone
C) colchicine
D) alcohol
E) formaldehyde

Question 15

Genetic recombination as a result of crossing over occurs more readily in genes that

A) are on the sex chromosomes.
B) are on the autosomes.
C) are located close together on the same chromosome.
D) are located farther apart on the same chromosome.
E) are located on different chromosomes.

Question 16

Which mutated gene is inherited in cases of cystic fibrosis?

A) BRCA-1
B) BRCA-2
C) aPOE-4
D) aPOE-2
E) CFTR

Question 17

A disease that is associated with changes in chloride and water movement into and out of exocrine glands, dry and thickened mucus in the airways, and an increase in the incidence of respiratory infections is

A) pneumonia.
B) influenza.
C) cystic fibrosis.
D) bird flu.
E) lung cancer.

Question 18

Karyotyping involves taking pictures of chromosomes during

A) prophase.
B) telophase.
C) metaphase.
D) interphase.
E) anaphase.

Question 19

Which concept helps to explain why close relatives have a varied mix of genetic traits?

A) segregation
B) dominance
C) incomplete dominance
D) independent assortment
E) codominance

Question 20

Which of the following is NOT true concerning homologous chromosomes?

A) There are two of each kind.
B) Each parent contributes one of each homologous pair.
C) Most homologous chromosomes carry the same genes for the same traits.
D) The number of homologous chromosomes is doubled in each generation.
E) Homologous chromosomes pair up during early meiosis.

Question 21

Pattern baldness is an example of a(n)

A) sex-linked trait.
B) sex-influenced trait.
C) sex-limited trait.
D) sex-exclusive trait.
E) inactivation trait.

Question 22

In genetic analyses, researchers know that linkage of genes will introduce exceptions to the principle of

A) dominance.
B) segregation.
C) recessiveness.
D) independent assortment.
E) chromosomal inheritance.

Question 23

A developing fetuses sex is determined by

A) female gamete (oogonia).
B) at the beginning of the third trimester.
C) male gamete (spermatogonia).
D) puberty.
E) autosomes.

Question 24

X inactivation occurs

A) at birth.
B) at the beginning of the second trimester.
C) after the first cleavages of the zygote.
D) at the moment of conception.
E) randomly depending on the individual.

Question 25

Concerning the sex chromosomes, which of the following is correct?

A) The Y chromosome carries a greater number of nonsexual traits.
B) X and Y are different in size but carry nearly equal numbers of genes.
C) The X chromosome carries more genes for nonsexual traits.
D) The X chromosome carries only gender-related genes.
E) The X chromosome carries the SRY gene.

Question 26

Autosomes in karyotypes are arranged

A) in descending size order.
B) in ascending size order.
C) randomly.
D) with the sex chromosomes at the beginning.
E) with all of the same-sized chromosomes grouped together.

Question 27

A condensed, female X chromosome is called a

A) Barr body.
B) Morgan sphere.
C) SRY gene.
D) karyotype.
E) linkage map.

Question 28

In human females, one of the sex chromosomes is switched off during early development in a phenomenon called

A) karyotyping.
B) X inactivation.
C) X linkage.
D) crossing over.
E) SRY activation.

Question 29

Sex chromosomes do all of the following EXCEPT

A) determine gender.
B) vary from one sex to another.
C) carry some genes that have nothing to do with sex.
D) appear in a diploid cell as either XX or XY.
E) appear in a haploid cell as either XX or XY.

Question 30

In a pedigree chart, a female who does not demonstrate the trait being studied is represented by a

A) darkened square.
B) clear diamond.
C) clear circle.
D) darkened triangle.
E) darkened oval.

Question 31

In a pedigree chart, a male showing the specific trait being studied is indicated by a

A) darkened square.
B) clear square.
C) darkened diamond.
D) clear triangle.
E) darkened circle.

Question 32

When the result of some genetic condition is a severe medical problem to the individual, it is called

A) an abnormality.
B) a disorder.
C) a deviation.
D) a carrier.
E) a pedigree.

Question 33

Which of the following statements is false?

A) The SRY gene is absent in females.
B) The SRY gene apparently is the gene that controls the development of male sexuality.
C) The development of maleness is by default because males lack two X chromosomes.
D) Genes on an X chromosome are called X-linked.
E) There is no difference in external genitalia of males or females until four weeks after conception when the genes determining sex begin to be expressed.

Question 34

A genetic X-linked condition in which females exhibit patches of lighter and darker pigmented skin is

A) psoriasis.
B) vitiligo.
C) ectodermal neoplasia.
D) hydrous ectodermal neoplasia.
E) incontinentia pigmenti.

Question 35

Pattern baldness is a trait that is referred to as sex-

A) linked.
B) related.
C) retarded.
D) influenced.
E) matched.

Question 36

Growth of a man's beard and a woman's breasts are governed by

A) sex-linked genes.
B) sex-influenced genes.
C) sex-exclusive genes.
D) sex-limited genes.
E) sex-independent genes.

Question 37

Sex influenced traits most likely appear due to the influence of

A) adrenal hormones.
B) estrogen.
C) testosterone.
D) both estrogen and testosterone.
E) growth hormone.

Question 38

With respect to chromosomes, the difference between normal human males and females is defined by which of the following?

A) In females, one X is deleted.
B) Females possess one X and one Y.
C) In males, an X is replaced by a Y.
D) Females have three Xs.
E) Males have two Xs and a Y.

Question 39

A set of symptoms that usually occur together and characterize a disorder is called

A) an abnormality.
B) a deviation.
C) a syndrome.
D) a carrier.
E) a pedigree.

Question 40

A genetically directed deviation from the average is called

A) an abnormality.
B) a disorder.
C) a syndrome.
D) a carrier.
E) a pedigree.

Question 41

The enzyme missing in Tay-Sachs disease is

A) cholinesterase.
B) hexosaminidase A.
C) neuraminidase.
D) hyaluronidase.
E) lactic dehydrogenase.

Question 42

The probability of producing a phenotypically normal child by two parents who are carriers for an autosomal recessive disorder is

A) 50 percent.
B) 0 percent.
C) 100 percent.
D) 25 percent.
E) 75 percent.

Question 43

A set of symptoms that characterize a disorder is referred to as

A) an abnormality.
B) a disorder.
C) a syndrome.
D) lethality.
E) a pedigree.

Question 44

Which of the following cannot be classified as a genetic disease?

A) a genetic predisposition to develop an allergy
B) Huntington disease
C) sickle cell anemia
D) cystic fibrosis
E) sickle cell trait

Question 45

In an autosomal dominant disorder such as Huntington's, two heterozygous parents have the probability of passing the gene on to ____ percent of their children.

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

Question 46

The probability of producing a child who suffers from cystic fibrosis by two parents who are carriers for the autosomal recessive disorder is

A) 50 percent.
B) 0 percent.
C) 100 percent.
D) 25 percent.
E) 75 percent.

Question 47

If gene replacement therapy became available

A) it would not work for humans because we have too many chromosomes.
B) it would involve a surgical technique that separates chromosomes that have failed to segregate properly during meiosis II.
C) it could be used to treat victims of a recessive disease by removing the dominant damaging autosomal allele and replacing it with a harmless one.
D) it would replace defective alleles with normal ones.
E) it would remove entire chromosomes from cells and repair the defective genes.

Question 48

A woman is diagnosed as having the genetic disease known as Huntington's disease. It is a rare defect caused by an autosomal dominant allele. The chance for any one of her eggs to carry the gene is

A) dependent on the sex of the child.
B) 1 out of 3.
C) dependent on the genotype of the woman.
D) 3 out of 4.
E) 0.

Question 49

Because geneticists can't use human subjects for experimentation, a ____ is used to obtain an analysis of a genetic family history.

A) blood test
B) hair sample.
C) tooth impression.
D) pedigree chart.
E) photograph analysis.

Question 50

Why don't recessive alleles that cause severe disorders disappear from human populations?

A) new alleles can arise by mutation.
B) in heterozygotes, the dominant allele suppresses the recessive one but does not eliminate its presence.
C) in heterozygotes, although the trait associated with the recessive allele is not demonstrated, the allele may be passed on to offspring.
D) some recessive traits are not lethal nor do they interfere with reproduction.
E) all of these.

Question 51

The most reasonable explanation for the fact that disorders such as cystic fibrosis do not disappear from the human population is that

A) it is an autosomal dominant disease.
B) new medical procedures allow most sufferers to live long enough to pass the gene on to offspring.
C) heterozygous carriers have one normal gene that masks the harmful gene.
D) the gene keeps mutating back to the harmful form.
E) persons with cystic fibrosis are made stronger by their affliction.

Question 52

Chromosomes other than those involved in sex determination are known as

A) nucleosomes.
B) heterosomes.
C) alleles.
D) autosomes.
E) liposomes.

Question 53

If a study of several pedigrees demonstrated that two parents are normal but their children express a trait, then the trait is controlled by a

A) codominant gene.
B) simple dominant gene.
C) recessive gene.
D) sex-linked gene.
E) No conclusion can be drawn.

Question 54

A carrier is a person who

A) carries a recessive gene for a genetic disorder but shows no signs or symptoms.
B) shows signs and symptoms of a genetic disorder only under conditions of stress or other illness.
C) carries a gene for a genetic disorder and shows signs and symptoms most of the time.
D) carries a gene for a genetic disorder and shows signs and symptoms all of the time.
E) carries a gene for a genetic disorder and shows a reduced degree of signs and symptoms.

Question 55

Which of these terms could be used to describe a person with one normal gene and one gene for a recessive disease?

A) heterozygote
B) carrier
C) a female
D) a male
E) homozygote

Question 56

An autosomal recessive disorder

A) requires that only one parent be a carrier.
B) displays its symptoms only in heterozygotes.
C) is more frequent in males than females.
D) can appear only in children of parents who both carry the gene.
E) is dominant in females.

Question 57

In which of the following does the onset of symptoms usually occur in individuals after childbearing age?

A) Tay-Sachs
B) hemophilia
C) Huntington's
D) muscular dystrophy
E) achondroplasia

Question 58

Symptoms of phenylketonuria (PKU) may be minimized or suppressed by a diet low in

A) serine.
B) glycine.
C) phenylalanine.
D) proline.
E) glutamic acid.

Question 59

Familial hypercholesterolemia is a condition explainable by

A) autosomal dominance.
B) X linkage.
C) autosomal recessiveness.
D) translocation.
E) chromosomal duplication.

Question 60

Tay-Sachs disease

A) is controlled by a simple recessive gene.
B) is a sex-linked disease more common in males.
C) occurs only in those individuals that receive two copies of a defective recessive gene.
D) is the result of the failure of chromosomes to separate so that an individual receives three instead of two chromosomes.
E) depends on which parent passes the gene to the child.

Question 61

Which substance is defective in Marfan syndrome?

A) sphingolipids
B) albumin
C) fibrillin
D) amyloid
E) LDLs

Question 62

A woman heterozygous for color blindness (an X-linked recessive allele) marries a man with normal color vision. What is the probability that their first child will be color-blind?

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

Question 63

Tay-Sachs disease is most common among

A) Blacks.
B) Hispanics.
C) Asians.
D) Jewish people of Eastern European descent.
E) Native Americans.

Question 64

If a daughter expresses an X-linked recessive gene, she inherited the trait from

A) her mother.
B) her father.
C) both parents.
D) neither parent.
E) her grandmother.

Question 65

Queen Victoria

A) was a carrier of hemophilia.
B) had a hemophilic parent.
C) had hemophilia.
D) married a man with hemophilia.
E) both had a hemophilic parent and married a man with hemophilia.

Question 66

Which of the following would be considered a carrier of a sex-linked recessive defect?

A) a man with the defect
B) a woman with the defect
C) a father of a son with the defect
D) the normal daughter whose father had the defect
E) a son of two unaffected parents

Question 67

An autosomal dominant condition that causes a person to grow no taller than about 4 feet 4 inches is

A) Marfan syndrome.
B) Tay-Sachs disease.
C) Huntington disease.
D) achondroplasia.
E) phenylketonuria.

Question 68

Which chemical builds up in Tay-Sachs disease?

A) albumin
B) glycogen
C) amyloid
D) fibrillin
E) sphingolipids

Question 69

Familial hypercholesterolemia affects approximately what paercentage of individuals?

A) 1/500
B) 1/5
C) 1/50
D) 1/1,000
E) 2/100

Question 70

Males tend to be affected in greater numbers by X-linked recessive genetic disorders than are females because

A) females have two dominant genes for the disorder.
B) males have only one X chromosomes.
C) males have a double dose of the gene.
D) Y chromosomes are not as strong as X chromosomes.
E) females have two dominant genes for the disorder and males have only one recessive gene for the disorder.

Question 71

Red-green color blindness is an X-linked recessive trait in humans. A color-blind woman and a man with normal vision have a son. What is the probability that the son is color-blind?

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

Question 72

Infants who are homozygous dominant for achondroplasia

A) are often stillborn.
B) grow to be no taller than two feet.
C) grow taller than individuals who are heterozygous.
D) attain a normal height.
E) do not develop arms and legs.

Question 73

Color blindness is an X-linked trait in humans. If a color-blind woman marries a man with normal vision, the children will be

A) all color-blind daughters, but normal sons.
B) all color-blind sons, but carrier daughters.
C) all normal sons, but carrier daughters.
D) all color-blind children.
E) all normal children.

Question 74

One of the major symptoms of Marfan syndrome is

A) hypertension.
B) rupture of the aorta.
C) retardation.
D) short stature.
E) abnormally short arms and legs.

Question 75

An X-linked carrier is a

A) homozygous dominant female.
B) heterozygous female.
C) homozygous recessive female.
D) homozygous male.
E) heterozygous male.

Question 76

Hemophilia

A) is rare in the human population.
B) is more common among men.
C) was common in English royalty.
D) is an X-linked recessive trait.
E) all of these

Question 77

A human X-linked recessive gene may be

A) found on the Y chromosome.
B) passed to daughters from their fathers.
C) passed to sons from their mothers.
D) expressed more commonly among females.
E) both passed to daughters from their fathers and passed to sons from their mothers.

Question 78

A color-blind man and a woman with normal vision whose father was color blind have a son. Color blindness, in this case, is caused by an X-linked recessive gene. If only the male offspring are considered, the probability that their son is color-blind is

A) 25 percent.
B) 50 percent.
C) 75 percent.
D) 100 percent.
E) 0 percent.

Question 79

A human X-linked gene is

A) found only in males.
B) more frequently expressed in females.
C) found on the Y chromosome.
D) transmitted from father to son.
E) found on the X chromosome.

Question 80

Red-green color blindness is an X-linked recessive trait in humans. What is the probability that a color-blind woman and a man with normal vision will have a color-blind daughter?

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