Bio Exam 2- Ch 7

Which of the following genotypes represents a human male? a. XY c. XX b. YY d. XO

a. XY

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

a. a mutation in a skin cell

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.

a. autosomal.

Chromosomes that are NOT involved in determining gender are known as a. autosomes. b. sex chromosomes. c. homologues. d. linked.

a. autosomes.

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.

a. found as a pair in females.

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.

a. heterozygous

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

a. inversion

The karyotype shown is from a(n) a. male. b. female. c. individual of undetermined sex. d. individual with a genetic disorder.

a. male.

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.

a. recessive mutations of genes located on autosomes.

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.

a. they are both considered genetic carriers for the disease.

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

a. two; homologous

Humans have ________ pairs of homologous chromosomes. a. 46 b. 23 c. 22 d. 44

b. 23

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.

b. Females must receive two copies of the recessive allele to exhibit the disorder, but males need only one copy.

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.

b. Half of the sons will be affected.

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.

b. Most affected individuals are males.

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.

b. No, because the Y chromosome contains the gene that makes an embryo male.

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.

b. They contain the same genes in the same locations.

Two copies of the same gene on a single chromosome would indicate a(n) ________ had occurred. a. deletion b. duplication c. inversion d. translocation

b. duplication

In the pedigree shown, the individual indicated represents a(n) a. healthy male. b. healthy female. c. affected male. d. affected female.

b. healthy female.

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

b. heterozygous

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

b. pedigree

Most inherited human genetic disorders are inherited as ________ alleles. a. dominant b. recessive c. homologous d. sex-linked

b. recessive

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.

b. recessive and autosomal.

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

b. three copies of chromosome 22

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

c. 50 percent

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.

c. A piece of a Y chromosome has become attached to one of the X chromosomes.

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

c. AA and Aa

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.

c. All of her eggs will contain one allele or the other, but not both alleles.

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.

c. None of the affected individuals have unaffected parents.

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.

c. SRY gene.

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.

c. The recessive allele is carried in the genome of heterozygotes, who do not suffer from the disease.

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.

c. The trait will be expressed in 100 percent of the male offspring.

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.

c. Their sons have a 50 percent chance of having the disorder.

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.

c. These diseases usually take effect later in life after people have had children.

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

c. a translocation between chromosome 14 and chromosome 15

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

c. percentage of all children likely to be affected by the disorder

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

c. whether the individual carries genetic mutations

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.

d. 50 percent will be carriers.

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.

d. A chromosomal alteration has occurred.

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.

d. Fifty percent of the children could be carriers of the disease.

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.

d. Genes in the section that was inverted could lose normal function.

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.

d. Half of her eggs will contain an extra copy of the X chromosome.

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.

d. Three young boys who are first cousins show symptoms of a neurological disorder.

A female who is a carrier of the sex-linked gene A has the genotype a. Aa. c. aa. b. AA. d. XAXa.

d. XAXa.

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

d. autosomal dominant

An allele that appears more frequently in males is most likely a. dominant. b. nonhomologous. c. homologous d. sex-linked

d. sex-linked.

The gender of a human child is determined by the a. loci. b. egg. c. autosomes. d. sperm.

d. sperm.

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.

d. tend to be expressed more in males than in females.

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.

d. the addition of an extra autosomal chromosome.