Deck 16: Human Genetics and the Human Genome

Question 1

The normal human karyotype contains ____ total chromosomes, consisting of ____ autosomes and ____ sex chromosomes.

A) 23; 22; 1
B) 44; 22; 1
C) 46; 22; 2
D) 46; 23; 0
E) 22; 20; 2

Answer 1

C

Question 2

The human genome contains about ____ genes, which comprises about _____ of the genome.

A) 25,000; 2%
B) 45,000; 2%
C) 25,000; 50%
D) 80,000; 2%
E) 100,000; 1%

Answer 2

A

Question 3

Figure 16-2 Refer to the accompanying figure. Based on the phenotypes of the third generation, the genotype of the father in the second generation must be:

A) homozygous for albinism.
B) heterozygous for hair color.
C) heterozygous for albinism.
D) X-linked.
E) dominant.

Answer 3

C

Question 4

Autosomal monosomy is not seen in live births because:

A) its effects are so small as to be overlooked.
B) its effects do not set in until adulthood.
C) its effects are so lethal as to cause spontaneous abortion early in pregnancy.
D) it only occurs in sex chromosomes and therefore does affect nonreproductive function.
E) the births lead to the establishment of a clone of abnormal cells

Question 5

What was revealed with the completion of the Human Genome Project?

A) The sequence of the entire human genome
B) The functions of all human genes
C) The knowledge that all genetic variations lead to genetic disease
D) The knowledge that all genetic variations are found outside of protein-coding regions
E) The number, but not the locations, genes in the human genome

Question 6

Human genetics can be most effectively studied using:

A) offspring raised under controlled conditions.
B) experimental matings between true-breeding strains.
C) controlled matings.
D) population studies of large extended families.
E) population studies of small extended families.

Question 7

In genomic imprinting:

A) a gene is imprinted in the progeny, depending upon the phenotype of the parent.
B) the expression of a gene depends on the parental phenotype.
C) a gene is imprinted in the progeny, depending upon the age of the parent.
D) the expression of a gene in the progeny depends upon which parent the gene is inherited from.
E) only dominant traits are expressed.

Question 8

Down syndrome is an example of a ____ condition.

A) monosomic
B) disomic
C) trisomic
D) polyploid
E) transgenic

Question 9

Persons having an XO karyotype are sterile females. They have ____ syndrome.

A) Turner
B) Klinefelter
C) Down (trisomy form)
D) Phenylketonuria
E) Down (translocation form)

Question 10

Figure 16-2 The genotypes of the normal females in the second generation in accompanying figure are:

A) homozygous for albinism.
B) heterozygous for hair color.
C) heterozygous for albinism.
D) X-linked.
E) unknown.

Question 11

Comparing the human and mouse genomes has revealed that the mouse and human:

A) share few genes.
B) genomes are identical.
C) genomes have no genes in common.
D) share most genes.
E) genomes have identical noncoding DNA.

Question 12

Down syndrome is characterized by:

A) single base mutations.
B) the presence of 47 chromosomes per somatic cell.
C) increasing risk with younger maternal age.
D) the presence of an extra chromosome 18 in each somatic cell
E) the same symptoms observed in each individual.

Question 13

The position of a specific gene on a chromosome can be determined by:

A) preparing a karyotype.
B) southern blotting.
C) genomic hybridization.
D) chromosome sorting.
E) fluorescent in situ hybridization.

Question 14

The sperm in the figure below were most likely produced by:

A) nondisjunction.
B) mutation.
C) X-linkage.
D) translocation.
E) normal meiosis.

Question 15

Nearly half of the pregnancies that end in miscarriage have:

A) trisomy of chromosome 21.
B) homozygosity for a recessive lethal allele.
C) major chromosomal abnormalities.
D) Klinefelter syndrome.
E) Down syndrome.

Question 16

Turner syndrome is an example of a __________ condition.

A) monosomic
B) disomic
C) trisomic
D) polyploid
E) fragile site

Question 17

Karyotyping is useful for determining:

A) the number of chromosomes in an individual.
B) the presence of recessive traits.
C) whether or not a specific gene is missing from a chromosome.
D) whether or not gene mutations have occurred.
E) the presence of sickle cell anemia.

Question 18

Figure 16-2 The inheritance pattern demonstrated by the pedigree in accompanying figure is:

A) autosomal recessive.
B) autosomal dominant.
C) X-linked recessive.
D) X-linked dominant.
E) undeterminable from these data.

Question 19

Colchicine is a drug that:

A) arrests cells in mitotic telophase.
B) stimulates meiosis.
C) prevents DNA replication.
D) arrests cells in mitotic metaphase.
E) prevents cells from entering prophase.

Question 20

Gene targeting has been used in mice to produce strains that were either homozygous or heterozygous for ____.

A) PKU
B) cystic fibrosis
C) Huntington's disease
D) sickle cell anemia
E) Tays Sachs Disease

Question 21

Polyploidy:

A) may be the result of more than one sperm fertilizing an egg.
B) is not lethal in humans.
C) may be the result of the failure of a chromosome to separate during meiosis.
D) can be due to nondisjunction for a chromosome.
E) is the mechanism of dosage compensation.

Question 22

In a chromosomal inversion, a segment of a chromosome is:

A) reversed.
B) duplicated.
C) lost.
D) attached to a nonhomologous chromosome.
E) deleted.

Question 23

Nondisjunction during mitosis leads to:

A) an individual with a clone of abnormal cells.
B) an individual with all abnormal cells.
C) death of the daughter cells.
D) nonviable sperm.
E) normal daughter cells.

Question 24

Hemophilia A is an example of a(n) _____ disease and is characterized by a lack of blood-clotting factor ____.

A) X-linked; VIII
B) sex-linked recessive; V
C) autosomal dominant; VIII
D) sex-linked dominant; V
E) autosomal recessive; VIII

Question 25

Which of the following must be true for a female to have hemophilia?

A) Her mother is not a carrier and her father has the disease.
B) Her mother is homozygous normal and her father is a carrier.
C) Her father and mother are heterozygous.
D) Her mother is a carrier and her father has the disease.
E) Her father is heterozygous.

Question 26

Individuals who are ____ for sickle cell hemoglobin tend to be ____ resistant to falciparum malaria, but do not experience the effects of sickled red blood cells.

A) homozygous dominant; more
B) homozygous dominant; less
C) homozygous recessive; less
D) heterozygous; more
E) heterozygous; less

Question 27

Polyploidy is the:

A) presence of more than two of a certain chromosome.
B) presence of only one of each chromosome.
C) presence of one extra chromosome.
D) presence of multiple sets of chromosomes.
E) general term for conditions such as Down or Turner syndrome.

Question 28

A fragile site:

A) is found only on the X chromosome.
B) occurs in only one of the sister chromatids.
C) is associated with cancerous cells.
D) is usually not inherited.
E) is the result of genomic imprinting.

Question 29

Autosomal aneuploidies arise by:

A) chromosome breakage and rejoining.
B) meiotic nondisjunction.
C) errors in crossing-over.
D) mistakes in chromosome replication.
E) mitotic nondisjunction.

Question 30

Translocation occurs when:

A) part of a chromosome breaks off and attaches to a nonhomologous chromosome.
B) part of a chromosome breaks off and attaches to a homologous chromosome.
C) crossing-over events occur.
D) genes move from one area on a chromosome to another area on the same chromosome.
E) a Y chromosome replaces an X chromosome in a female cell.

Question 31

An individual who inherits the specific chromosome ____ deletion from his/her ____ will most likely have Prader-Willi syndrome rather than Angelman syndrome.

A) 15; mother
B) 15; father
C) 21; mother
D) 21; father
E) 12; father

Question 32

What explains the viability of individuals with aneuploidies for the sex chromosomes?

A) Sex chromosomes carry less information than autosomes.
B) The lack of crossing-over between the X and the Y chromosomes.
C) Sex chromosomes are smaller than most autosomes.
D) The information on sex chromosomes is duplicated on the autosomes.
E) Dosage compensation, by which one X chromosome per cell is inactivated.

Question 33

A karyotype reveals that an individual is XYY. Based on your knowledge of human genetics, you correctly conclude that this individual has ____, and is a phenotypically _____.

A) Turner syndrome; sterile female
B) Turner syndrome; fertile female
C) Klinefelter syndrome; sterile male
D) Klinefelter syndrome; fertile male
E) XXY karyotype; fertile male

Question 34

Huntington's disease is caused by a:

A) rare recessive allele.
B) nucleotide triplet repeat.
C) monosomic condition.
D) dominant X-linked allele.
E) deletion of part of chromosome 4.

Question 35

Maternal PKU can result in serious effects in fetuses. This problem occurs because:

A) the fetus is homozygous for PKU and therefore cannot metabolize phenylalanine.
B) the fetus is usually homozygous dominant and therefore has PKU.
C) the mother is heterozygous for PKU and therefore cannot metabolize phenylalanine.
D) the mother is homozygous dominant for PKU and cannot metabolize phenylalanine.
E) the mother is homozygous recessive for PKU and cannot metabolize phenylalanine.

Question 36

A couple in which the woman is homozygous dominant for clotting ability and the man has hemophilia A will produce:

A) carrier daughters and affected sons.
B) affected daughters and affected sons.
C) carrier daughters and normal sons.
D) normal daughters and normal sons.
E) offspring of unknown genotype for this gene.

Question 37

Fragile X syndrome:

A) results in learning, attention, and hyperactivity disabilities in males.
B) is not inherited from the parents.
C) is characterized by a fragile site at the tip of the Y chromosome.
D) results from a deletion of CGG sequences in the fragile X gene.
E) is due to genomic imprinting..

Question 38

Cri du chat syndrome arises from:

A) trisomy for chromosome 5.
B) deletion of part of chromosome 5.
C) a 14/21 reciprocal translocation.
D) nondisjunction.
E) a duplication of part of chromosome 15.

Question 39

Aneuploidies describe:

A) a phenomenon that only occurs in plants.
B) a condition in which an extra chromosome is present or one is absent.
C) a defect that is always fatal in humans.
D) an uncommon condition in humans.
E) mutations that almost always have a beneficial effect on an individual.

Question 40

Which of the following are inborn errors of metabolism?

A) PKU and alkaptonuria
B) sickle cell anemia and hemophilia
C) cystic fibrosis and Tay-Sachs disease
D) Huntington's disease and fragile X syndrome
E) cri-du-chat syndrome and Down syndrome

Question 41

What are the predicted phenotypes of the children from a union of a woman who is heterozygous for hemophilia and a man who is normal? (Use the Punnett square to verify your answer.)

A) 100% normal
B) 75% hemophilia: 25 % normal
C) 50% hemophilia: 50% normal
D) 25 % hemophilia: 75% normal
E) 100% hemophilia

Question 42

Which statement accurately characterizes an ethical consideration surrounding human genetics?

A) Nonrelatives are more likely than relatives to carry the same harmful alleles.
B) Genetic discrimination is not yet possible, even with all the known effects of genetic information.
C) In the current ethical climate, genetic privacy is not a significant concern.
D) Consanguineous matings are prohibited by half of U.S. States due to increased risk autosomal recessive alleles.
E) Most insurance companies have instituted policies against keeping genetic information on their policy holders.

Question 43

In individuals with cystic fibrosis:

A) the mucus enhances the action of the cilia that line the bronchi.
B) the mucus prevents the growth of dangerous bacteria in the respiratory system.
C) the mucus in the respiratory system is thinner than in unaffected individuals.
D) abnormal mucous secretions occur throughout the body systems.
E) abnormal mucous secretions inhibit infections by bacteria.

Question 44

Make a sketch showing how nondisjunction in meiosis can result in Down syndrome.

Question 45

What is the current status of gene therapy?

A) It is currently being used effectively to cure cystic fibrosis.
B) It has been terminated because clinical trials have shown it to be ineffective.
C) It is being evaluated to assess the risks associated with potential side effects.
D) The number of clinical trials is increasing at an almost uncontrollable rate.
E) It may be considered in the future, but currently the technology is not available.

Question 46

Why are most infants with phenylketonuria usually healthy at birth?

A) The defect causing the condition has usually been repaired by that time.
B) The mother breaks down phenylalanine for both herself and her fetus.
C) The infant can produce sufficient quantities of the enzymes needed by birth.
D) Phenylalanine can be completely excreted in infants.
E) Phenylalanine is completely metabolized in infants.

Question 47

Geneticists study pedigrees in order to predict how traits determined by phenotype are inherited from one generation to the next.
_________________

Question 48

Gene therapy involves:

A) replacing all mutant alleles in body cells.
B) replacing poor copies of alleles with normal alleles.
C) replacing a mutant allele in certain body cells with a normal allele.
D) repairing mutant alleles in certain body cells.
E) improving gene expression in key body cells.

Question 49

A genetic counselor will know that the probability of having a child affected with a condition inherited as an autosomal recessive would be:

A) 0.5 or 50% if both parents were homozygous normal.
B) 0.5 or 50% if both parents were heterozygous.
C) 0.25 or 25% if both parents were homozygous normal.
D) 0.25 or 25% if both parents were heterozygous.
E) 0% if both parents were heterozygous.

Question 50

Genetic screening can be used to identify:

A) only diseases caused by more than one gene.
B) diseases caused by single gene mutations.
C) non-genetic conditions..
D) chromosomal abnormalities.
E) predicted date of birth.

Question 51

Preimplantation genetic diagnosis is done:

A) on cells of an in vitro fertilized embryo.
B) in the womb, before birth.
C) after a woman is pregnant, but before the embryo implants.
D) with the help of ultrasound.
E) before fertilization on the sperm and the egg.

Question 52

The selective advantage linked to the high frequency of the cystic fibrosis allele in Caucasians is:

A) an increased resistance to falciparum malaria.
B) the prevention of excessive water loss associated with certain types of diarrhea.
C) production of an enzyme to break down cholera toxin.
D) increased mucous secretions for the removal of infectious cells.
E) an increased probability of Salmonella infection.

Question 53

According to data from the ENCODE project, approximately 80% of the human genome is associated with biological function.

Question 54

Genome-wide association scans compare the proteins of individuals with a particular disease to individuals without the disease.
_________________

Question 55

What is genetic counseling? Briefly explain the role of a genetic counselor.

Question 56

Identify human genetic defects or diseases that are inherited as:
A. an autosomal recessive.
B. an autosomal dominant.
C. an X-linked recessive.

Question 57

Tay-Sachs disease is a(n) ____ disease that results in blindness, intellectual disability, and death due to ____.

A) sex-linked; the absence of one of the sex chromosomes
B) autosomal recessive; accumulation of lipids in brain cells
C) X-linked; accumulation of acetyltransferases in brain cells
D) autosomal; sickled red blood cells
E) autosomal dominant; accumulation of mucus in the lungs

Question 58

Why has the dominant mutant allele for Huntington's disease been able to persist in human populations despite its devastating effects?

A) It has a heterozygote advantage.
B) Its symptoms do not typically show until after the individual has had children.
C) Its effects are not expressed in heterozygous individuals.
D) Its effects are only expressed in homozygous recessive individuals.
E) Its effects are only expressed in homozygous dominant individuals.

Question 59

FISH distinguishes chromosomes by using more than one fluorescent-tagged RNA strand, which will bind to complementary DNA sequences on a specific chromosome.
_________________

Question 60

An advantage of chorionic villus sampling (compared with amniocentesis) is that:

A) chorionic villus sampling detects a much wider range of genetic defects than does amniocentesis.
B) chorionic villus sampling is much less expensive than is amniocentesis.
C) chorionic villus sampling is much less invasive than amniocentesis.
D) chorionic villus sampling is much easier to perform than amniocentesis.
E) chorionic villus sampling can be performed much earlier than amniocentesis.

Question 63

Nondisjunction of the XY pair during the first meiotic division can produce sperm with 2 X chromosomes and 2 Y chromosomes.
_________________

Question 64

In fragile X syndrome, the fragile X gene contains a nucleotide triplet that repeats 200-1000 times.

Question 65

The science of comparative genomics to study human gene function is possible because much of the human genome is conserved among other closely related species.

Question 66

Sickle cell anemia and cystic fibrosis are examples of a(n) homozygote advantage.
_________________

Question 67

In trisomy 21, while all genetic information is intact, a(n) abnormal copy of this chromosome creates a genetic imbalance which causes abnormal physical and mental development.
_________________

Question 68

In reciprocal translocation, two homologous chromosomes exchange segments.
_________________

Question 69

Describe how amniocentesis is used in the prenatal diagnosis of human genetic abnormalities. Then compare and contrast the benefits and risks associated with amniocentesis and chorionic villus sampling.

Question 70

The Human Genome Project was completed in 2012 and revealed a genomic map of 38 million SNPs.

Question 71

Discuss the necessity and benefits of the Genetic Information Nondiscrimination Act (GINA) of 2008.

Question 72

Compare and contrast the following three terms: polyploidy, aneuploidy, and nondisjunction. Identify and briefly discuss examples of each of these conditions.

Question 73

What is the role of heterozygote advantage in maintaining high frequencies of mutant alleles in populations?

Question 74

Males with Klinefelter syndrome lack a Barr Body.
_______________

Question 75

Polyploidy may arise from the failure of chromosomes to separate during cell division or by the fertilization of an egg by more than one sperm.
_________________