Biology CHP 11

A diploid cell of baker's yeast has 32 chromosomes. How many chromosomes are in each of its haploid spores? A. 16 B. 64 C. 8 D. 1 E. 32

A

A woman is heterozygous for the CF-associated gene (the alleles are represented here by the letters A and a. Assuming that meiosis occurs normally, which answer choice represents eggs that she can produce? A. A or a B. a C. A D. Aa E. AA

A

An alien has 82 total chromosomes in each of its body cells. The chromosomes are paired, making 41 pairs. If the alien's gametes undergo meiosis, what are the number and arrangement (paired or not) of chromosomes in one of its gametes? A. 41 unpaired chromosomes B. 164 paired chromosomes C. 41 paired chromosomes D. 82 unpaired chromosomes E. 82 paired chromosomes

A

How do the two alleles of the CFTR gene in a lung cell differ? A. They are inherited from different parents. B. They are inherited from different parents, they are on different chromosomes, and only one is expressed. C. There is no difference because they are both the same gene. D. Only one is expressed. E. One is on chromosome 7 and one is on chromosome 3.

A

Use the following information for this question: Phenylketonuria is considered to be an inborn error of metabolism. It is a recessive genetic condition in which the enzyme that breaks down the amino acid phenylalanine is defective or missing. Testing of all newborns allows this condition to be detected at birth. A special diet that severely minimizes phenylalanine (e.g., by avoiding diet sodas and most usual sources of protein) can treat the condition. In this scenario, two carriers of both cystic fibrosis and phenylketonuria have a child. What is the probability that the child will have cystic fibrosis and be a carrier for phenylketonuria? A. 12.5% B. 6.25% C. 56.25% D. 0% E. 18.75%

A

Which statement is true of a single human liver cell? A. all of these B. The number of chromosomes in this liver cell is referred to as diploid. C. There are two alleles for each gene. D. There are 46 chromosomes present. E. There is one allele on each chromosome.

A

In diploid organisms, having two homologues of each chromosome can be beneficial if one allele of a gene encodes a nonfunctional protein. Can haploid organisms avoid the negative effects of nonfunctional alleles? A. No, because there are two chromosomes each with a single allele that is always the same, and one cannot compensate for the other being nonfunctional. B. No, because there is only one allele for the gene in each cell, and the nonfunctional allele has no other allele to mask it. C. Yes, because there are two chromosomes each with a single allele that is always the same, and one can compensate for the other being nonfunctional. D. Yes, because there is only one allele for the gene in each cell, and the nonfunctional allele will be masked by another allele of a different kind. E. Yes, because there are always other alleles for other genes that will compensate for a nonfunctional allele.

B

Meiosis differs from mitosis in the _____. A. way in which sister chromatids separate B. number of chromosomes in each ending cell C. number of sister chromatids in the starting cells D. number of chromosomes in the starting cells E. number of cells produced immediately after the starting cells divide

B

What is the genotype of a person with cystic fibrosis? A. The genotype includes 2 additional chromosomes with the mutant CFTR gene, making a total of 25 chromosomes. B. The genotype includes two mutant CFTR genes, one each on the homologous chromosomes for chromosome 7. C. The genotype includes only one homologous chromosome 7; the second chromosome 7 is missing. D. The genotype includes one mutant CFTR gene and one normal gene, one each on the homologous chromosomes for chromosome 7. E. The genotype includes two mutant CFTR genes, both on a single homologous chromosome 7; the other homologous chromosome 7 is normal

B

If meiosis were to fail and a cell skipped meiosis I, so that meiosis II was the only meiotic division, how would you describe the resulting cells? A. haploid cells with 23 pairs of chromosomes B. haploid cells with 23 unpaired chromosomes C. diploid cells with 23 pairs of chromosomes D. diploid cells with 23 unpaired chromosomes E. none of the above

C

One of the purposes of meiosis is to _____. A. increase genetic diversity in the diploid-starting cells B. double the number of chromosomes per gamete C. reduce the chromosome number in each resulting cell by half D. produce four zygotes instead of only two (as produced in mitosis) E. increase the number of embryos per fertilization

C

What does it mean to say that a person has a heterozygous genotype for a disease and no disease phenotype? A. It means that the person exhibits the symptoms of the disease if the disease allele is recessive. B. It means that the person has two copies of the normal allele. C. It means that the person does not show symptoms of the disease if the disease allele is recessive. D. It means that the person is a carrier who has already sired children who show symptoms of the disease. E. It means that the person has two copies of the disease allele.

C

Why is it possible for two healthy parents to give birth to a child with a genetic defect such as cystic fibrosis? A. CF is not passed to children from their parents; it comes from their grandparents. B. CF is caused by the inheritance of too many "normal" genes; the parents would be unaffected. C. CF is only evident in individuals with two mutant alleles; a healthy parent could carry both a defective allele and a normal allele. D. CF is normally caused by a mutation that occurs in the fetus during pregnancy, and it does not affect the mother. E. CF is normally caused by a mutation that occurs only in the sperm and eggs of the parents, so their bodies are not affected.

C

A human female has _____ chromosomes in each skin cell and _____ chromosomes in each egg. A. 23; 46 B. 46; 46 C. 92; 46 D. 46; 23 E. 23; 23

D

Besides recombination, what other event in meiosis increases the genetic diversity of the gametes? A. the random way in which gametes fuse together to make uniquely different sperm and eggs B. the random exchange of DNA segments between maternal chromosomes C. the random exchange of DNA segments between paternal chromosomes D. the random line-up and separation of maternal and paternal chromosomes E. the way in which chromosomes are replicated in meiosis II

D

Use the following information for this question: Phenylketonuria is considered to be an inborn error of metabolism. It is a recessive genetic condition in which the enzyme that breaks down the amino acid phenylalanine is defective or missing. Testing of all newborns allows this condition to be detected at birth. A special diet that severely minimizes phenylalanine (e.g., by avoiding diet sodas and most usual sources of protein) can treat the condition. In this scenario, two carriers of both cystic fibrosis and phenylketonuria have a child. What is the probability that the child will have both cystic fibrosis and phenylketonuria? A. 18.75% B. 0% C. 12.5% D. 6.25% E. 56.25%

D

Assume that Emily (who has CF, a recessive disease (aa)) decides to have children with a man who does not have CF and who has no family history of CF. What combination of gametes can each of them produce, and what is the probability that they will have a child who is a carrier for CF? A. Emily: aa, man: AA; 50% probability B. Emily: Aa, man: Aa; 100% probability C. Emily: aa, man: Aa; 100% probability D. Emily: Aa, man: AA; 50% probability E. Emily: aa, man: AA; 100% probability

E

Children often have many of the phenotypes of their parents because _____. A. they carry the same combinations of alleles that their parents have B. they have the exact same genotypes as their parents C. they inherit mutations that make their bodies appear identical to one or both parents D. the cells of embryos divide by meiosis, a process that yields genetic duplicates E. they inherit half of their genetic material from each parent

E

In order for a child to develop cystic fibrosis _____. A. more than one egg in the mother must carry the CF allele B. more than one sperm in the father must carry the CF allele C. genetic recombination must occur in the mother but not the father D. genetic recombination must occur in the father but not the mother E. a sperm carrying a CF allele must fertilize an egg that also has that allele

E

Which phrase accurately describes meiosis? A. ends with four gametes that are not the same genetically B. contains two rounds of division (meiosis I and meiosis II) C. none of these D. takes one diploid cell to make four haploid cells E. all of these

E

Which statement is true of a single human gamete? A. all of these B. none of these C. There are two alleles per trait on each chromosome. D. There are 46 chromosomes present. E. There is one allele per trait on each chromosome.

E

Women can inherit alleles of a gene called BRCA1 that puts them at higher risk for breast cancer. The alleles associated with elevated cancer risk are dominant. Of the genotypes listed below, which carries the lowest genetic risk of developing breast cancer? A. BB B. Bb C. Bb and bb D. All of these genotypes carry equal risk. E. bb

E