Chapter 14

According to Figure 14-1, what is the approximate probability that a human offspring will be female? a. 10% b. 25% c. 50% d. 75%

c. 50%

What percentage of human sperm cells carry an X chromosome? a. 0% b. 25% c. 50% d. 100%

c. 50%

Examine the pedigree in Figure 14-3. The allele for the presence of a white forelock is dominant. What is the probability of the couple labeled 2 of having a child with a white forelock? a. 25% b. 50% c. 75% d. 100%

c. 75%

What prevents insurance companies from discriminating against people based on information derived from genetic tests? a. Only scientists can read the results of complicated genetic tests. b. Genetic tests don't show information about genetic disorders. c. Discrimination based on genetic information is against the law. d. People with genetic diseases cannot do business with private insurance companies.

c. Discrimination based on genetic information is against the law.

The human genome was sequenced a. by sequencing each gene on each chromosome, one at a time. b. in order of the chromosome number on a karyotype. c. by finding overlapping regions between sequenced DNA fragments. d. by first organizing all the single-base differences into haplotypes.

c. by finding overlapping regions between sequenced DNA fragments.

Which was the first step in sequencing the human genome? a. locating overlapping sequences b. identifying genes by finding promoters c. cutting the DNA into manageable pieces d. sorting between introns and exons

c. cutting the DNA into manageable pieces

Compared with normal hemoglobin, the hemoglobin of a person with sickle cell disease is a. longer. b. shorter. c. less soluble. d. more soluble.

c. less soluble.

Human males have a. one X chromosome only. b. two X chromosomes. c. one X and one Y chromosome. d. two Y chromosomes.

c. one X and one Y chromosome.

Which of the following form(s) a Barr body? a. one of the Y chromosomes in a male cell b. one of the X chromosomes in a male cell c. one of the X chromosomes in a female cell d. both of the X chromosomes in a female cell

c. one of the X chromosomes in a female cell

Colorblindness is more common in males than in females because the allele for colorblindness is a. dominant and located on the X chromosome. b. recessive and located on the Y chromosome. c. recessive and located on the X chromosome. d. recessive and located on the Y chromosome.

c. recessive and located on the X chromosome.

Because the X chromosome contains genes that are vital for normal development, no baby has been born a. with one X chromosome. b. with three X chromosomes. c. without an X chromosome. d. with four X chromosomes.

c. without an X chromosome.

How many chromosomes are shown in a normal human karyotype? a. 2 b. 23 c. 44 d. 46

d. 46

Which enzyme(s) in Figure 14-8 would be best for cutting DNA to make fragments with sticky ends? a. EcoRI and HaeIII b. HaeIII and BamI c. HaeIII alone d. EcoRI and BamI

d. EcoRI and BamI

Which of the following diseases and conditions does not appear until late in a person's life? a. cystic fibrosis b. sickle cell disease c. colorblindness d. Huntington disease

d. Huntington disease

Which of the following combinations of sex chromosomes represents a female? a. XY b. XXY c. XXXY d. XX

d. XX

Sex-linked genes are located on a. the autosomal chromosomes. b. the X chromosome only. c. the Y chromosome only. d. both the X chromosome and the Y chromosome.

d. both the X chromosome and the Y chromosome.

What is the role of restriction enzymes in studying the human genome? a. copying pieces of DNA b. labeling different nucleotides with different colors of dyes c. separating different pieces of DNA based on their size d. cutting large DNA molecules into smaller pieces

d. cutting large DNA molecules into smaller pieces

What is illustrated in Figure 14-7? a. mutation b. dominance c. electrophoresis d. nondisjunction

d. nondisjunction

\More than forty percent of the proteins coded for in the human genome are a. used to help protect the DNA. b. coded for on the X and Y chromosomes c. thought to have the same function. d. similar to proteins found in other organisms.

d. similar to proteins found in other organisms.

Examine the pedigree in Figure 14-3. The allele for the presence of a white forelock is dominant. Therefore, we can tell from the chart that in the couple labeled 2 a. the male is heterozygous and the female is homozygous. b. the male is homozygous and the female is heterozygous. c. the male is homozygous and the female is homozygous. d. the male is heterozygous and the female is heterozygous.

d. the male is heterozygous and the female is heterozygous.

Which piece of DNA would move fastest in gel electrophoresis? A segment that is a. 100 base pairs long. b. 1,000 base pairs long. c. 5,000 base pairs long. d. 100,000 base pairs long.

a. 100 base pairs long.

About how much of our DNA encodes the instructions for building proteins? a. 2 percent b. 10 percent c. 50 percent d. 100 percent

a. 2 percent

Which of the following is caused by a dominant allele? a. Huntington's disease b. colorblindness c. cystic fibrosis d. sickle-cell disease

a. Huntington's disease

Sickle cell disease is caused by a a. change in one allele. b. change in the size of a chromosome. c. change in two proteins. d. change in the number of chromosomes in a cell.

a. change in one allele.

If the allele for having a white forelock is dominant, family members WITHOUT a white forelock are a. homozygous recessive. b. heterozygous. c. homozygous dominant. d. trisomal.

a. homozygous recessive.

The failure of chromosomes to separate during meiosis is called a. nondisjunction. b. X-chromosome inactivation. c. Turner's syndrome. d. Down syndrome.

a. nondisjunction.

Human females produce egg cells that have a. one X chromosome. b. two X chromosomes. c. one X or one Y chromosome. d. one X and one Y chromosome.

a. one X chromosome.

What did scientists in the Human Genome Project look for in DNA to identify the locations of genes? a. promoters b. sex-linked genes c. CFTR genes d. autosomes

a. promoters

Which of the following can be used to cut DNA so it can be studied? a. restriction enzymes b. gel electrophoresis c. karyotypes d. haplotypes

a. restriction enzymes

A human female inherits a. two copies of every gene located on the X chromosome. b. twice as many sex chromosomes as a human male inherits. c. one copy of every gene located on the Y chromosome. d. all of the same genes that a human male inherits.

a. two copies of every gene located on the X chromosome.

How many generations are shown in the pedigree in Figure 14-5? a. 2 b. 4 c. 6 d. 8

b. 4

Which of the following statements is true? a. Females cannot have hemophilia. b. A colorblind girl's father must be colorblind. c. A sex-linked allele cannot be dominant. d. A colorblind boy's father must be colorblind.

b. A colorblind girl's father must be colorblind.

Which of the following pairs of genotypes result in the same phenotype? a. IAIA and IAIB b. IBIB and IBi c. IBIB and IAIB d. IBi and ii

b. IBIB and IBi

Why is it helpful to sequence many human genomes, instead of just one? a. Scientists can confirm that everyone's genome is identical. b. Scientists can find how the human genome varies. c. Scientists can find out how to get rid of viral DNA from our cells. d. Scientists can provide insurance companies with everyone's genome.

b. Scientists can find how the human genome varies.

For the pedigree in Figure 14-6, shaded symbols represent afflicted people. Males are squares; women are circles. If the trait is a sex-linked trait carried on the X chromosome, what is true about the mother represented by circle 1? a. She has two alleles for the disorder. b. She has one allele for the disorder. c. She has no alleles for the disorder. d. She has the genotype XXY.

b. She has one allele for the disorder.

What new field is described by the overlap area in the Venn diagram in Figure 14-9? a. biotechnology b. bioinformatics c. gene therapy d. genetic engineering

b. bioinformatics

In cystic fibrosis, a change in a single gene causes the protein called CFTR to a. become less soluble. b. fold improperly. c. destroy the cell membrane. d. transport sodium ions.

b. fold improperly.

People who are heterozygous for sickle cell disease are generally healthy because they a. are resistant to many different diseases. b. have some normal hemoglobin in their red blood cells. c. are not affected by the gene until they are elderly. d. produce more hemoglobin than they need

b. have some normal hemoglobin in their red blood cells.

People who are heterozygous for sickle cell disease are generally healthy because they a. are resistant to many different diseases. b. have some normal hemoglobin in their red blood cells. c. are not affected by the gene until they are elderly. d. produce more hemoglobin than they need.

b. have some normal hemoglobin in their red blood cells.

A cat that has spots of more than one color a. has no Barr bodies. b. is probably female. c. is probably male. d. could be male or female.

b. is probably female.

The formation of a Barr body inactivates a. half of the genes on one X chromosome in a female cell. b. one whole X chromosome in a female cell. c. one whole Y chromosome in a male cell. d. one gene on one X chromosome in a male cell.

b. one whole X chromosome in a female cell.

The Human Genome Project is an attempt to a. sequence every person's DNA. b. sequence the DNA of every human gene. c. cure infectious human diseases. d. identify all restriction enzymes.

b. sequence the DNA of every human gene.

If nondisjunction occurs during meiosis, a. only two gametes may form instead of four. b. some gametes may have an extra copy of some genes. c. the gamete cannot join another to form a organism. d. the gametes redistribute chromosomes after meiosis.

b. some gametes may have an extra copy of some genes.