Question 1

Which of the following characteristics of the structure of DNA was determined directly from X-ray diffraction photographs of crystallized DNA?

Accepted Answer

A) the double helical structure 
B) the length of a given DNA molecule 
C) the sequence of nucleotides 
D) the frequency of A versus T nucleotides 
A) the double helical structure 
B) the length of a given DNA molecule 
C) the sequence of nucleotides 
D) the frequency of A versus T nucleotides

Question 2

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?

Accepted Answer

A) It synthesizes RNA nucleotides to make a primer. 
B) It catalyzes the lengthening of telomeres. 
C) It joins Okazaki fragments together. 
D) It unwinds the parental double helix. 
A) It synthesizes RNA nucleotides to make a primer. 
B) It catalyzes the lengthening of telomeres. 
C) It joins Okazaki fragments together. 
D) It unwinds the parental double helix.

Question 3

What is the function of topoisomerase?

Accepted Answer

A) relieving strain in the DNA ahead of the replication fork 
B) elongating new DNA at a replication fork by adding nucleotides to the existing chain 
C) adding methyl groups to bases of DNA 
D) unwinding of the double helix 
A) relieving strain in the DNA ahead of the replication fork 
B) elongating new DNA at a replication fork by adding nucleotides to the existing chain 
C) adding methyl groups to bases of DNA 
D) unwinding of the double helix

Question 4

Assume that you are trying to insert a gene into a plasmid.Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X.The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y.You have a plasmid with a single site for Y but not for X.Your strategy should be to

Accepted Answer

A) insert the fragments cut with restriction enzyme X directly into the plasmid without cutting the plasmid. 
B) cut the plasmid with restriction enzyme X,and insert the fragments cut with restriction enzyme Y into the plasmid. 
C) cut the DNA again with restriction enzyme Y,and insert these fragments into the plasmid cut with the same enzyme. 
D) cut the plasmid twice with restriction enzyme Y,and ligate the two fragments onto the ends of the DNA fragments cut with restriction enzyme X. 
A) insert the fragments cut with restriction enzyme X directly into the plasmid without cutting the plasmid. 
B) cut the plasmid with restriction enzyme X,and insert the fragments cut with restriction enzyme Y into the plasmid. 
C) cut the DNA again with restriction enzyme Y,and insert these fragments into the plasmid cut with the same enzyme. 
D) cut the plasmid twice with restriction enzyme Y,and ligate the two fragments onto the ends of the DNA fragments cut with restriction enzyme X.

Question 5

-In the late 1950s,Meselson and Stahl grew bacteria in a medium containing "heavy" (radioactive)nitrogen (15N)and then transferred them to a medium containing 14N,which is a nonradioactive form of nitrogen.They then extracted DNA from the bacteria and centrifuged it to separate the DNA of different densities.Which of the results in figure above would be expected after one round of DNA replication in the presence of 14N?

Accepted Answer

A) A 
B) B 
C) C 
D) D 
A) A 
B) B 
C) C 
D) D

Question 6

Which of the following statements most accurately describes transformation in bacteria?

Accepted Answer

A) Transformation is the creation of a strand of DNA from an RNA molecule. 
B) Transformation is the creation of a strand of RNA from a DNA molecule. 
C) Transformation is the infection of cells by a phage DNA molecule. 
D) Transformation is the assimilation of external DNA into a cell. 
A) Transformation is the creation of a strand of DNA from an RNA molecule. 
B) Transformation is the creation of a strand of RNA from a DNA molecule. 
C) Transformation is the infection of cells by a phage DNA molecule. 
D) Transformation is the assimilation of external DNA into a cell.

Question 7

Which of the following statements correctly describes one of Chargaff's rules regarding DNA?

Accepted Answer

A) The percentages of adenine and cytosine are roughly equal,as are the percentages of guanine and thymine in the DNA of a given species. 
B) DNA has a double helical structure. 
C) DNA base composition does not vary between species. 
D) The percentages of adenine and thymine are roughly equal,as are the percentages of guanine and cytosine in the DNA of a given species. 
A) The percentages of adenine and cytosine are roughly equal,as are the percentages of guanine and thymine in the DNA of a given species. 
B) DNA has a double helical structure. 
C) DNA base composition does not vary between species. 
D) The percentages of adenine and thymine are roughly equal,as are the percentages of guanine and cytosine in the DNA of a given species.

Question 8

A group of six students has taken samples of their own cheek cells,purified the DNA,and used a restriction enzyme known to cut at zero,one,or two sites in a particular gene of interest.
Analysis of the data obtained shows that two students each have two fragments,two students each have three fragments,and two students each have one only.What does this demonstrate?

Accepted Answer

A) Each pair of students has a different gene for this function. 
B) The two students who have two fragments have one restriction site in this region. 
C) The two students who have two fragments have two restriction sites within this gene. 
D) Each of these students is heterozygous for this gene. 
A) Each pair of students has a different gene for this function. 
B) The two students who have two fragments have one restriction site in this region. 
C) The two students who have two fragments have two restriction sites within this gene. 
D) Each of these students is heterozygous for this gene.

Question 9

Which of the following statements correctly describes one characteristic of DNA replication in eukaryotes?

Accepted Answer

A) In the leading strand,DNA is replicated in short pieces called Okazaki fragments,which are then joined together at the end of the process. 
B) DNA is replicated in the 3' to 5' direction in the leading strand. 
C) In the lagging strand,DNA is replicated in short pieces called Okazaki fragments,which are then joined together at the end of the process. 
D) Helicase joins the Okazaki fragments together in the lagging strand. 
A) In the leading strand,DNA is replicated in short pieces called Okazaki fragments,which are then joined together at the end of the process. 
B) DNA is replicated in the 3' to 5' direction in the leading strand. 
C) In the lagging strand,DNA is replicated in short pieces called Okazaki fragments,which are then joined together at the end of the process. 
D) Helicase joins the Okazaki fragments together in the lagging strand.

Question 10

During DNA replication in E.coli,which of the following enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?

Accepted Answer

A) helicase 
B) DNA polymerase III 
C) ligase 
D) DNA polymerase I 
A) helicase 
B) DNA polymerase III 
C) ligase 
D) DNA polymerase I

Question 11

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium?

Accepted Answer

A) Transform bacteria with a recombinant DNA molecule.Cut the plasmid DNA using restriction enzymes.Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments.Extract plasmid DNA from bacterial cells.Use ligase to seal plasmid DNA to nonplasmid DNA. 
B) Cut the plasmid DNA using restriction enzymes.Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments.Use ligase to seal plasmid DNA to nonplasmid DNA.Extract plasmid DNA from bacterial cells.Transform bacteria with a recombinant DNA molecule. 
C) Extract plasmid DNA from bacterial cells.Cut the plasmid DNA using restriction enzymes.Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments.Use ligase to seal plasmid DNA to nonplasmid DNA.Transform bacteria with a recombinant DNA molecule. 
D) Extract plasmid DNA from bacterial cells.Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments.Use ligase to seal plasmid DNA to nonplasmid DNA.Transform bacteria with a recombinant DNA molecule.Cut the plasmid DNA using restriction enzymes. 
A) Transform bacteria with a recombinant DNA molecule.Cut the plasmid DNA using restriction enzymes.Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments.Extract plasmid DNA from bacterial cells.Use ligase to seal plasmid DNA to nonplasmid DNA. 
B) Cut the plasmid DNA using restriction enzymes.Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments.Use ligase to seal plasmid DNA to nonplasmid DNA.Extract plasmid DNA from bacterial cells.Transform bacteria with a recombinant DNA molecule. 
C) Extract plasmid DNA from bacterial cells.Cut the plasmid DNA using restriction enzymes.Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments.Use ligase to seal plasmid DNA to nonplasmid DNA.Transform bacteria with a recombinant DNA molecule. 
D) Extract plasmid DNA from bacterial cells.Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments.Use ligase to seal plasmid DNA to nonplasmid DNA.Transform bacteria with a recombinant DNA molecule.Cut the plasmid DNA using restriction enzymes.

Question 12

Which of the following lists of structures correctly represents the order of increasingly higher levels of organization of chromatin?

Accepted Answer

A) nucleosome,30-nm chromatin fiber,looped domain 
B) looped domain,30-nm chromatin fiber,nucleosome 
C) looped domain,nucleosome,30-nm chromatin fiber 
D) nucleosome,looped domain,30-nm chromatin fiber 
A) nucleosome,30-nm chromatin fiber,looped domain 
B) looped domain,30-nm chromatin fiber,nucleosome 
C) looped domain,nucleosome,30-nm chromatin fiber 
D) nucleosome,looped domain,30-nm chromatin fiber

Question 13

A student isolates,purifies,and combines in a test tube a variety of molecules needed for DNA replication.After adding some DNA to the mixture,replication occurs,but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long.What has the student probably left out of the mixture?

Accepted Answer

A) DNA polymerase 
B) DNA ligase 
C) Okazaki fragments 
D) primase 
A) DNA polymerase 
B) DNA ligase 
C) Okazaki fragments 
D) primase

Question 14

Which of the following characteristics of the structure of DNA allows it to carry a large amount of hereditary information?

Accepted Answer

A) the sequence of bases 
B) phosphate-sugar backbones 
C) complementary pairing of bases 
D) different five-carbon sugars 
A) the sequence of bases 
B) phosphate-sugar backbones 
C) complementary pairing of bases 
D) different five-carbon sugars

Question 15

Which enzyme in E.coli catalyzes the elongation of a DNA strand in the 5' → 3' direction?

Accepted Answer

A) primase 
B) DNA ligase 
C) DNA polymerase III 
D) topoisomerase 
A) primase 
B) DNA ligase 
C) DNA polymerase III 
D) topoisomerase

Question 16

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?

Accepted Answer

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. 
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.

Question 17

In an analysis of the nucleotide composition of DNA,which of the following will be found in a given DNA molecule?

Accepted Answer

A) A = C 
B) A = G and C = T 
C) A + C = G + T 
D) G + C = T + A 
A) A = C 
B) A = G and C = T 
C) A + C = G + T 
D) G + C = T + A

Question 18

Why do histones bind tightly to DNA?

Accepted Answer

A) Histones are positively charged,and DNA is negatively charged. 
B) Histones are negatively charged,and DNA is positively charged. 
C) Both histones and DNA are strongly hydrophobic. 
D) Histones are covalently linked to the DNA. 
A) Histones are positively charged,and DNA is negatively charged. 
B) Histones are negatively charged,and DNA is positively charged. 
C) Both histones and DNA are strongly hydrophobic. 
D) Histones are covalently linked to the DNA.

Question 19

What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?

Accepted Answer

A) DNA polymerase can join new nucleotides only to the 3' end of a preexisting strand. 
B) Helicases and single-strand binding proteins work at the 5' end. 
C) The origins of replication occur only at the 5' end. 
D) DNA ligase works only in the 3' → 5' direction. 
A) DNA polymerase can join new nucleotides only to the 3' end of a preexisting strand. 
B) Helicases and single-strand binding proteins work at the 5' end. 
C) The origins of replication occur only at the 5' end. 
D) DNA ligase works only in the 3' → 5' direction.

Question 20

In analyzing the number of different bases in a DNA sample,which result would be consistent with the base-pairing rules?

Accepted Answer

A) A = G 
B) A + G = C + T 
C) A + T = G + C 
D) A = C 
A) A = G 
B) A + G = C + T 
C) A + T = G + C 
D) A = C

Exam 13: The Molecular Basis of Inheritance

Which of the following characteristics of the structure of DNA was determined directly from X-ray diffraction photographs of crystallized DNA?

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?

What is the function of topoisomerase?

Which of the following statements most accurately describes transformation in bacteria?

Which of the following statements correctly describes one of Chargaff's rules regarding DNA?

Which of the following statements correctly describes one characteristic of DNA replication in eukaryotes?

During DNA replication in E.coli,which of the following enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium?

Which of the following lists of structures correctly represents the order of increasingly higher levels of organization of chromatin?

Which of the following characteristics of the structure of DNA allows it to carry a large amount of hereditary information?

Which enzyme in E.coli catalyzes the elongation of a DNA strand in the 5' → 3' direction?

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?

In an analysis of the nucleotide composition of DNA,which of the following will be found in a given DNA molecule?

Why do histones bind tightly to DNA?

What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?

In analyzing the number of different bases in a DNA sample,which result would be consistent with the base-pairing rules?

Introduction: Evolution and the Foundations of Biology

The Chemical Context of Life

Carbon and the Molecular Diversity of Life

A Tour of the Cell

Membrane Transport and Cell Signaling

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

Gene Expression: From Gene to Protein

Regulation of Gene Expression

Development,stem Cells,and Cancer

Viruses

Genomes and Their Evolution

Descent With Modification

Phylogeny

The Evolution of Populations

The Origin of Species

Broad Patterns of Evolution

Early Life and the Diversification of Prokaryotes

The Origin and Diversification of Eukaryotes

The Colonization of Land by Plants and Fungi

The Rise of Animal Diversity

Plant Structure and Growth

Resource Acquisition,nutrition,and Transport in Vascular Plants

Reproduction and Domestication of Flowering Plants

Plant Responses to Internal and External Signals

Homeostasis and Endocrine Signaling

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Reproduction and Development

Neurons,synapses,and Signaling

Nervous and Sensory Systems

Motor Mechanisms and Behavior

Population Ecology and the Distribution of Organisms

Ecological Communities

Ecosystems and Energy

Conservation Biology and Global Change

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