mastering biology chapter 13

A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon- based life-form that has DNA. You grow the cells in 15N medium for several generations and then transfer them to 14N medium. Which pattern in the figure would you expect after one round of DNA replication if the DNA was replicated in a conservative manner? A. B. C. D. E.

B

Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? A. 8% B. 16% C. 31% D. 42%

A

During DNA replication, which of the following enzymes separates the DNA strands during replication? A. helicase B. DNA polymerase III C. ligase D. DNA polymerase I E. primase

A

What are the repetitive DNA sequences present at the ends of eukaryotic chromosomes called? A. telomeres B. chromomeres C. sarcomeres D. centromeres E. polypeptides

A

Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction? A. DNA polymerase III B. primase C. topoisomerase D. helicase E. DNA ligase

A

Which of the following help(s) to hold the DNA strands apart while they are being replicated? A. single-strand binding proteins B. ligase C. DNA polymerase D. nuclease E. primase

A

Which of the following is an example of "recombinant DNA technology"? A. introducing a human gene into a bacterial plasmid B. cloning genes from homologous pairs of chromosomes C. manipulating a meiotic crossing-over event D. alternate alleles assorting independently E. combining alternate alleles of a gene in a single cell

A

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? A. It catalyzes the lengthening of telomeres. B. It joins Okazaki fragments together. C. It unwinds the parental double helix. D. It synthesizes RNA nucleotides to make a primer. E. It stabilizes the unwound parental DNA

B

Which of the following is true of DNA during interphase? A. It is in the form of highly condensed chromosomes; it is called heterochromatin. B. It exists as chromatin and is less condensed than mitotic chromosomes. C. It exists as chromatin and is unavailable for gene expression. D. It exists as chromatin; it is completely uncoiled and loose E. It is in the form of highly condensed chromosomes and is unavailable for gene expression.

B

Which of the following statements accurately describes why Taq polymerase is used in PCR? A. It is heat stable, and it binds more readily than other polymerases to the primers. B. It is heat stable and can withstand the heating step of PCR. C. It binds more readily than other polymerases to the primers. D. Only minute amounts are needed for each cycle of PCR. E. It has regions that are complementary to the primers.

B

Which of the following enzymes synthesizes short segments of RNA? A. helicase B. DNA polymerase III C. ligase D. DNA polymerase I E. primase

E

Which of the following functions in the regulation of gene expression? A. nucleoids B. plasmids C. nucleases D. telomeres E. euchromatin

E

What are chromosomes made of? A. DNA, heterochromatin, and histone proteins B. DNA, RNA, and proteins C. DNA and proteins D. DNA E. DNA and euchromatin

C

What is meant by the description "antiparallel" regarding the two strands of nucleic acids that make up DNA? A. The twisting nature of DNA creates nonparallel strands. B. One strand contains only purines and the other contains only pyrimidines. C. The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. D. Base pairings create unequal spacing between the two DNA strands.

C

What is the function of DNA polymerase III? A. to seal together the broken ends of DNA strands B. to degrade damaged DNA molecules C. to add nucleotides to the 3' end of a growing DNA strand D. to rejoin the two DNA strands (one new and one old) after replication E. to unwind the DNA helix during replication

C

Which "ingredients" for PCR and for the dideoxy chain-termination method of DNA sequencing are the same? A. template DNA, reverse transcriptase, DNA primers B. enucleated eggs, reverse transcriptase, free nucleotides C. free nucleotides, DNA polymerase, DNA primers D. nucleic acid probes, DNA polymerase, DNA ligase E. mRNA, reverse transcriptase, free nucleotides

C

Griffith's experiments with S. pneumoniae were significant because they showed that traits could be transferred from one organism to another. What else did he find that was significant? A. DNA is the genetic material B. A virus made the bacteria pathogenic. C. Heat kills bacteria. D. The transferred traits were heritable. E. Protein could not be the genetic material.

D

How is transformation in bacteria most accurately described? A. the infection of cells by a phage DNA molecule B. the type of semiconservative replication shown by DNA C. the creation of a strand of RNA from a DNA molecule D. assimilation of external DNA into a cell E. the creation of a strand of DNA from an RNA molecule

D

In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine. Which of the following investigators was (were) responsible for this discovery? A. Frederick Griffith B. Matthew Meselson and Franklin Stahl C. Oswald Avery D. Erwin Chargaff E. Alfred Hershey and Martha Chase

D

In his transformation experiments, what did Griffith observe? A. Infecting mice with nonpathogenic strains of bacteria makes them resistant to pathogenic strains. B. Mutant mice were resistant to bacterial infections. C. Mixing a heat-killed nonpathogenic strain of bacteria with a living pathogenic strain makes the pathogenic strain nonpathogenic. D. Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.

D

In nucleotide excision repair, damaged DNA is excised by what enzyme(s)? A. ligase B. helicase C. primase D. nuclease E. DNA polymerases

D

In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (15N) and then transferred them to a medium containing 14N. Which of the results in the figure would be expected after one round of DNA replication in the presence of 14N? A. B. C. D. E.

D

The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that A. ATP is found only in human cells; the nucleoside triphosphates are found in all animal and plant cells. B. the nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups. C. triphosphate monomers are active in the nucleoside triphosphates, but not in ATP. D. the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose. E. ATP contains three high-energy bonds; the nucleoside triphosphates have two.

D

What is the function of helicase in DNA replication? A. It relieves strain from twisting of the double helix as it is unwound. B. It joins together Okazaki fragments. C. It adds nucleotides to the new strand in the 5' to 3' direction. D. It untwists the double helix and separates the two DNA strands E. It checks for errors in the newly synthesized DNA strand.

D

What is the function of topoisomerase? A. adding methyl groups to bases of DNA B. stabilizing single-stranded DNA at the replication fork C. unwinding of the double helix D. relieving strain in the DNA ahead of the replication fork E. elongating new DNA at a replication fork by adding nucleotides to the existing chain

D

What process repairs damage to a preexisting double helix? A. transformation B. mismatch repair C. operon repair D. nucleotide excision repair E. proofreading

D

Who conducted the X-ray diffraction studies that were key to the discovery of the structure of DNA? A. Chargaff B. Griffith C. Meselson and Stahl D. Franklin E. McClintock

D

DNA replication is said to be semiconservative. What does this mean? A. The old double helix is degraded, and half of its nucleotides are used in the construction of two new double helices. B. Each new double helix consists of one old and one new strand C. One of the two resulting double helices is made of two old strands, and the other is made of two new strands. D. Half of the old strand is degraded, and half is used as a template for the replication of a new strand E. One strand of the new double helix is made of DNA, and the other strand is made of RNA

B

In the Hershey and Chase experiment that helped confirm that DNA, not protein, was the hereditary material, what was the key finding? A. Radioactively labeled sulfur was present inside the infected bacteria B. Radioactively labeled phosphorus was present inside the infected bacteria C. Radioactively labeled carbon was present inside the infected bacteria. D. Radioactively labeled sulfur was found outside of the infected bacteria. E. Radioactively labeled phosphorus was found outside of the infected bacteria.

B

In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts? A. DNA contains purines, whereas protein includes pyrimidines. B. DNA contains phosphorus, whereas protein does not. C. RNA includes ribose, whereas DNA includes deoxyribose sugars. D. DNA contains nitrogen, whereas protein does not E. DNA contains sulfur, whereas protein does not.

B

It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information based on which of the following characteristics? A. complementary pairing of bases B. the sequence of bases C. phosphate-sugar backbones D. different five-carbon sugars

B

The leading and the lagging strands of DNA formed during DNA replication differ in that A. the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. B. the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. C. The leading strand is synthesized at twice the rate of the lagging strand. D. the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end.

B

Gel electrophoresis separates DNA fragments on the basis of what characteristic? A. charge B. restriction sites C. length D. sequence E. sequence

C

During DNA replication, which of the following enzymes covalently connects segments of DNA? A. helicase B. DNA polymerase III C. ligase D. DNA polymerase I E. primase

C

During DNA replication, which of the following enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments? A. helicase B. DNA polymerase III C. ligase D. DNA polymerase I E. primase

D