Week 3 Quiz

Which of the following must occur for a mismatch error to be repaired? A. The sequence of nucleotides in the damaged DNA sequence guides the synthesis of the correct DNA sequence. B. DNA repair proteins identify damaged DNA. C. The damaged DNA undergoes DNA replication one more time. D. DNA-eating enzymes within the nucleus destroy entire strands of damaged DNA.

B. DNA repair proteins identify damaged DNA.

The number of chromosomes in secondary spermatocytes is fewer than in primary spermatocytes because __________ are separated during meiosis __________ A. sister chromatids; II B. sister chromatids; I C. homologous pairs; II D. homologous pairs; I

D. homologous pairs; I

What information cannot be determined by a karyotype A. allele versions B. the individual's sex C. the number of autosomes D. chromosomal deletions

A. allele versions

It could help meet transplant needs to use a patient's own stem cells to grow a human liver in a pig embryo modified by CRISPR. As an additional and essential step in the process to ensure the liver is safe for the patient, CRISPR should be used to: A. knock out all of the porcine endogenous retrovirus (PERV) genes to prevent infection of the human patient with porcine endogenous retroviruses. B. knock out all of the pig brain genes to prevent the pig brain cells from infecting the patient. C. insert human hemoglobin DNA into the pig embryo to make it possible for the growing pig to support the human liver. D. insert human immune cell DNA into the pig embryo to make it more similar to the patient.

A. knock out all of the porcine endogenous retrovirus (PERV) genes to prevent infection of the human patient with porcine endogenous retroviruses.

In bacteria, the antibiotic tetracycline blocks the site where tRNA molecules enter the ribosome. The most likely reason that bacteria die from treatment with tetracycline is because the antibiotics: A. prevents the bacteria from assembling essential proteins. B. inhibits the cell from producing the mRNA. C. causes tRNA rather than mRNA to be made into proteins. D. causes the tRNA molecules to randomly arrange into proteins that do not function.

A. prevents the bacteria from assembling essential proteins.

A rapidly dividing cell is exposed to a chemical that converts the bond that forms between adenine and thymine to a stronger covalent bond. Which of the following is most likely to occur? A. DNA replication would be faster because covalent bonds require less energy to break than hydrogen bonds. B. DNA replication would not occur because the two nucleotide strands that make up the DNA molecule would not be able to separate. C. DNA replication would occur more slowly because DNA repair proteins would have to fix the covalent bonds before replication could begin. D. DNA replication would produce two molecules of DNA with mutations at every base that once held an A-T base pair.

B. DNA replication would not occur because the two nucleotide strands that make up the DNA molecule would not be able to separate.

If follicle-stimulating hormone (FSH) and luteinizing hormone (LH) stimulate the production of sperm and the release of testosterone in males in a homeostatic negative feedback loop pathway, an increase in which of the following hormones might inhibit the production of sperm A. FSH and LH B. testosterone C. LH D. FSH

B. testosterone

Which of the following statements about sexual reproduction in humans is true? A. Only one parent is needed to produce offspring. B. Only one parent contributes genes to the offspring. C. Both parents contribute genes to the offspring. D. The offspring are identical to their parents.

C. Both parents contribute genes to the offspring.

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. She carries a rare mutation. C. Each of her eggs will contain one allele or the other but not both alleles. D. All of her eggs will contain both of the alleles for that gene.

C. Each of her eggs will contain one allele or the other but not both alleles.

Asexual and sexual reproduction in animals is similar in that both: A. produce offspring that have double the amount of genetic information of the parent(s). B. rely on parental chromosomes to mix in new ways. C. generate offspring that carry parental genes. D. increase genetic variation in the offspring.

C. generate offspring that carry parental genes.

Gamete formation in human males is different from gamete formation in human females in that human male A. have a shorter reproductive life span than human females. B. make two polar bodies during spermatogenesis, whereas human females do not. C. make sperm throughout their lives, beginning at puberty, whereas human females are born with all their primary oocytes poised to develop into eggs that may be fertilized. D. produce gametes in the gonads, whereas human females produce eggs in the gut.

C. make sperm throughout their lives, beginning at puberty, whereas human females are born with all their primary oocytes poised to develop into eggs that may be fertilized.

If a segment of double-stranded DNA has 20 percent adenine (A), how much of it is cytosine (C)? A. 20 percent B. 40 percent C. 60 percent D. 30 percent

D. 30 percent

A person is genetically XX and develops as a male. How could this be explained? A. The SRY gene was deleted in this individual. B. In humans, males are XX. C. An error in karyotyping this individual must have occurred because XX individuals cannot develop into males. D. A segment of a Y chromosome has become attached to one of the X chromosomes.

D. A segment of a Y chromosome has become attached to one of the X chromosomes.

When examining the two complementary strands of nucleotides in one DNA molecule, it would be expected that the sum of __________ in one strand would be __________ the sum of the __________ in the other strand" A. Ts and As; equal to; Cs and Gs B. As and Cs; less than; Ts and Gs C. Ts and As; greater than; Ts and As D. Gs and Cs; equal to; Gs and Cs

D. Gs and Cs; equal to; Gs and Cs

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. The homozygous dominant individuals protect the recessive allele in their genomes. B. Alleles are never lost from a population. C. The homozygous recessive individuals give their alleles to other individuals before they die from the disease. D. The recessive allele is carried in the genome of heterozygotes, who do not suffer from the disease.

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

Some organisms switch from male to female or vice versa. The most likely reason for the change is the: A. ability to reproduce asexually versus sexually. B. loss of chromosomes from one year to the next. C. loss of reproductive ability. D. availability of environmental resources.

D. availability of environmental resources.

The information in a gene is encoded by the: A. rRNA that transfers amino acids to ribosomes. B. introns of eukaryotic cells. C. amino acids that make up the genes. D. base sequences of the gene's DNA.

D. base sequences of the gene's DNA.

In humans, the tRNA with the anticodon AAU carries the amino acid leucine. In plants, this tRNA would: A. not carry an amino acid. B. carry the same amino acid. C. not have an anticodon. D. carry a different amino acid.

B. carry the same amino acid.

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. Genes in the section that was inverted may lose normal function. D. The chromosome will take on a circular configuration.

C. Genes in the section that was inverted may lose normal function.

Prokaryotes lack membrane-enclosed organelles and thus do not have nuclei. Therefore, prokaryotes: A. cells are unable to undergo transcription and translation. B. cells do not need to undergo transcription. C. cells do not need to undergo translation. D. transcription and translation both take place in the cytoplasm.

D. transcription and translation both take place in the cytoplasm.