Chapter 16 Practice Test

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% e) It cannot be determined from the information provided

a

It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in which of the following? a) sequence of bases b) phosphate-sugar backbones c) complementary pairing of bases d) side groups of nitrogenous bases e) different five-carbon sugars

a

The leading and the lagging strands differ in that a) 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 b) 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 c) the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together d) the leading strand is synthesized at twice the rate of the lagging strand

a

In his transformation experiments, what did Griffith observe? a) Mutant mice were resistant to bacterial infections. b) Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form c) Mixing a heat-killed nonpathogenic strain of bacteria with a living pathogenic strain makes the pathogenic strain nonpathogenic d) Infecting mice with nonpathogenic strains of bacteria makes them resistant to pathogenic strains e) Mice infected with a pathogenic strain of bacteria can spread the infection to other mice

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 sulfur, whereas protein does not b) DNA contains phosphorus, whereas protein does not c) DNA contains nitrogen, whereas protein does not d) DNA contains purines, whereas protein includes pyrimidines e) RNA includes ribose, whereas DNA includes deoxyribose sugars

b

Replication in prokaryotes differs from replication in eukaryotes for which of the following reasons? a) Prokaryotic chromosomes have histones, whereas eukaryotic chromosomes do not. b) Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many. c) The rate of elongation during DNA replication is slower in prokaryotes than in eukaryotes. d) Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not. e) Prokaryotes have telomeres, and eukaryotes do not.

b

What is meant by the description "antiparallel" regarding the strands that make up DNA? a) The twisting nature of DNA creates nonparallel strands b) The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand c) Base pairings create unequal spacing between the two DNA strands d) One strand is positively charged and the other is negatively charged e) One strand contains only purines and the other contains only pyrimidines

b

Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which of the following? a) the evolution of telomerase enzyme b) DNA polymerase that cannot replicate the leading strand template to its 5' end c) gaps left at the 5' end of the lagging strand d) gaps left at the 3' end of the lagging strand because of the need for a primer e) the "no ends" of a circular chromosome

c

In his work with pneumonia-causing bacteria and mice, Griffith found that a) the protein coat from pathogenic cells was able to transform nonpathogenic cells b) heat-killed pathogenic cells causes pneumonia c) some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic d) the polysaccharide coat of bacteria caused pneumonia e) bacteriophages injected DNA into bacteria

c

Which enzyme catalyzes the elongation of a DNA strand in the 5' ---> 3' direction? a) primase b) DNA ligase c) DNA polymerase II d) topoisomerase e) helicase

c

Which of the enzymes covalently connects segments of DNA? a) I (helicase) b) II (DNA polymerase III) c) III (ligase) d) IV (DNa polymerase I) e) V (primase)

c

After mixing a heat-killed, phosphorescent (light-emitting) strain of bacteria with a living, nonphosphorescent strain, you discover that some of the living cells are now phosphorescent. Which observation(s) would provide the best evidence that the ability to phosphoresce is a heritable trait? a) DNA passed from the heat-killed strain to the living strain b) Protein passed from the heat-killed strain to the living strain c) The phosphorescence in the living strain is especially bright d) Descendants of the living cells are also phosphorescent e) Both DNA and protein passed from the heat-killed strain to the living strain

d

At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3' CCTAGGCtGCAATCC 5'. An RNA primer is formed starting at the t of the template. Which of the following represents the primer sequence? a) 5' GCCTAGG 3' b) 3' GCCTAGG 5' c) 5' ACGTTAGG 3' d) 5' ACGUUAGG 3' e) 5' GCCUAGG 3'

d

How does the enzyme telomerase meet the challenge of replicating the ends of linear chromosomes? a) It adds a single 5' cap structure that resists degradation by nucleases b) It causes specific double-strand DNA breaks that result in blunt ends on both strands c) It causes linear ends of the newly replicated DNA to circularize d) It catalyzes the lengthening of telomeres, compensating for the shortening that occurs during replication e) It adds numerous GC pairs which resist hydrolysis and maintain chromosome integrity

d

Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells are impaired in what way? a) they cannot replicate DNA b) they cannot undergo mitosis c) they cannot exchange DNA with other cells d) they cannot repair thymine dimers e) they do not recombine homologous chromosomes during meiosis

d

Which of the following help(s) to hold the DNA strand apart while they are being replicated? a) primase b) ligase c) DNA polymerase d) single-strand binding proteins e) exonuclease

d

A new DNA strand elongates only in the 5' to 3' direction because a) DNA polymerase begins adding nucleotides at the 5' end of the template b) Okazaki fragments prevent elongation in the 3' to 5' direction c) the polarity of the DNA molecule prevents addition of nucleotides at the 3' end d) replication must progress toward the replication fork e) DNA polymerase can only add nucleotides to the free 3' end

e

Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base? a) One of the daughter cells, but not the other, would have radioactive DNA b) Neither of the two daughter cells would be radioactive c) All four bases of the DNA would be radioactive d) Radioactive thymine would pair with nonradioactive guanine e) DNA in both daughter cells would be radioactive

e

The DNA of telomeres has been found to be highly conserved throughout the evolution of eukaryotes. What does this most probably reflect? a) the inactivity of this DNA b) the low frequency of mutations occurring in this DNA c) that new evolution of telomeres continues d) that mutations in telomeres are relatively advantageous e) that the critical function of telomeres must be maintained

e

Which of the enzymes synthesizes short segments of RNA? a) I (helicase) b) II (DNA polymerase III) c) III (ligase) d) IV (DNa polymerase I) e) V (primase)

e