Question 1

The DNA of telomeres has been found to be highly conserved throughout the evolution of eukaryotes. What does this most probably reflect?

Accepted Answer

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 
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

Question 2

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?

Accepted Answer

A) No proofreading will occur. 
B) No replication fork will be formed. 
C) The DNA will supercoil. 
D) Replication will occur via RNA polymerase alone. 
E) Replication will require a DNA template from another source. 
A) No proofreading will occur. 
B) No replication fork will be formed. 
C) The DNA will supercoil. 
D) Replication will occur via RNA polymerase alone. 
E) Replication will require a DNA template from another source.

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 
E) stabilizing single-stranded DNA at the replication fork 
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 
E) stabilizing single-stranded DNA at the replication fork

Question 4

If a cell were unable to produce histone proteins, which of the following would be a likely effect?

Accepted Answer

A) There would be an increase in the amount of "satellite" DNA produced during centrifugation. 
B) The cell's DNA couldn't be packed into its nucleus. 
C) Spindle fibres would not form during prophase. 
D) Amplification of other genes would compensate for the lack of histones. 
E) Pseudogenes would be transcribed to compensate for the decreased protein in the cell. 
A) There would be an increase in the amount of "satellite" DNA produced during centrifugation. 
B) The cell's DNA couldn't be packed into its nucleus. 
C) Spindle fibres would not form during prophase. 
D) Amplification of other genes would compensate for the lack of histones. 
E) Pseudogenes would be transcribed to compensate for the decreased protein in the cell.

Question 5

The leading and the lagging strands differ in that

Accepted Answer

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) 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.

Question 6

Which of the enzymes separates the DNA strands during replication?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 7

Until the mid-1940s, which molecule was favoured as the molecule of inheritance?

Accepted Answer

A) lipid 
B) carbohydrate 
C) protein 
D) DNA 
E) RNA 
A) lipid 
B) carbohydrate 
C) protein 
D) DNA 
E) RNA

Question 8

A new DNA strand elongates only in the 5' to 3' direction because

Accepted Answer

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. 
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.

Question 9

Use the following information to answer the questions below.
The green algae Chlamydomonas is said to be GC rich.
-What does this mean?

Accepted Answer

A) There is a tendency for its DNA to recombine with G or C bases. 
B) The organism prefers an environment rich in GTP or cAMP. 
C) RNA primers only bind to GC pairs. 
D) There is characteristically more GC base pairs in the DNA sequence than in an average organism's DNA sequence. 
E) It has more mismatched pairs of GC bases than are found in the average organism. 
A) There is a tendency for its DNA to recombine with G or C bases. 
B) The organism prefers an environment rich in GTP or cAMP. 
C) RNA primers only bind to GC pairs. 
D) There is characteristically more GC base pairs in the DNA sequence than in an average organism's DNA sequence. 
E) It has more mismatched pairs of GC bases than are found in the average organism.

Question 10

A biochemist isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. When she adds 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 she probably left out of the mixture?

Accepted Answer

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

Question 11

Avery et al. showed that DNA was the inheritable agent in what year?

Accepted Answer

A) 1918 
B) 1944 
C) 1949 
D) 1952 
E) 1960 
A) 1918 
B) 1944 
C) 1949 
D) 1952 
E) 1960

Question 12

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. 
E) Histones are highly hydrophobic, and DNA is hydrophilic. 
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. 
E) Histones are highly hydrophobic, and DNA is hydrophilic.

Question 13

Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication?

Accepted Answer

A) double-stranded DNA, four kinds of dNTPs, primers, origins 
B) topoisomerases, telomerases, polymerases 
C) G-C rich regions, polymerases, chromosome nicks 
D) nucleosome loosening, four dNTPs, four rNTPs 
E) ligase, primers, nucleases 
A) double-stranded DNA, four kinds of dNTPs, primers, origins 
B) topoisomerases, telomerases, polymerases 
C) G-C rich regions, polymerases, chromosome nicks 
D) nucleosome loosening, four dNTPs, four rNTPs 
E) ligase, primers, nucleases

Question 14

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?

Accepted Answer

A) 8% 
B) 16% 
C) 31% 
D) 42% 
E) It cannot be determined from the information provided. 
A) 8% 
B) 16% 
C) 31% 
D) 42% 
E) It cannot be determined from the information provided.

Question 15

The images above are of DNA at various levels of coiling and folding. Use this image to answer the questions below.
-For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus, labelling the nitrogens would provide a stronger signal than labelling the phosphates. Why won't this experiment work?

Accepted Answer

A) There is no radioactive isotope of nitrogen. 
B) Radioactive nitrogen has a half-life of 100 000 years, and the material would be too dangerous for too long. 
C) Avery et al. have already concluded that this experiment showed inconclusive results. 
D) Although there are more nitrogens in a nucleotide, labelled phosphates actually have 16 extra neutrons; therefore, they are more radioactive. 
E) Amino acids (and thus proteins)also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins. 
A) There is no radioactive isotope of nitrogen. 
B) Radioactive nitrogen has a half-life of 100 000 years, and the material would be too dangerous for too long. 
C) Avery et al. have already concluded that this experiment showed inconclusive results. 
D) Although there are more nitrogens in a nucleotide, labelled phosphates actually have 16 extra neutrons; therefore, they are more radioactive. 
E) Amino acids (and thus proteins)also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.

Question 16

What is the function of DNA polymerase III?

Accepted Answer

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

Question 17

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. 
E) It stabilizes the unwound parental DNA. 
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. 
E) It stabilizes the unwound parental DNA.

Question 18

Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which of the following?

Accepted Answer

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 
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

Question 19

The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an uncommon base, opposite thymine. What combination of proteins could repair such damage?

Accepted Answer

A) nuclease, DNA polymerase, DNA ligase 
B) telomerase, primase, DNA polymerase 
C) telomerase, helicase, single-strand binding protein 
D) DNA ligase, replication fork proteins, adenylyl cyclase 
E) nuclease, telomerase, primase 
A) nuclease, DNA polymerase, DNA ligase 
B) telomerase, primase, DNA polymerase 
C) telomerase, helicase, single-strand binding protein 
D) DNA ligase, replication fork proteins, adenylyl cyclase 
E) nuclease, telomerase, primase

Question 20

At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3' C C T A G G C T G C A A T C C 5'
An RNA primer is formed starting at the underlined T (T)of the template. Which of the following represents the primer sequence?

Accepted Answer

A) 5' G C C T A G G 3' 
B) 3' G C C T A G G 5' 
C) 5' A C G T T A G G 3' 
D) 5' A C G U U A G G 3' 
E) 5' G C C U A G G 3' 
A) 5' G C C T A G G 3' 
B) 3' G C C T A G G 5' 
C) 5' A C G T T A G G 3' 
D) 5' A C G U U A G G 3' 
E) 5' G C C U A G G 3'

Exam 16: The Molecular Basis of Inheritance

The DNA of telomeres has been found to be highly conserved throughout the evolution of eukaryotes. What does this most probably reflect?

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?

What is the function of topoisomerase?

If a cell were unable to produce histone proteins, which of the following would be a likely effect?

The leading and the lagging strands differ in that

Which of the enzymes separates the DNA strands during replication?

Until the mid-1940s, which molecule was favoured as the molecule of inheritance?

A new DNA strand elongates only in the 5' to 3' direction because

Use the following information to answer the questions below. The green algae Chlamydomonas is said to be GC rich. -What does this mean?

Avery et al. showed that DNA was the inheritable agent in what year?

Why do histones bind tightly to DNA?

Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication?

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?

What is the function of DNA polymerase III?

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

Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which of the following?

The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an uncommon base, opposite thymine. What combination of proteins could repair such damage?

At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3' C C T A G G C T G C A A T C C 5' An RNA primer is formed starting at the underlined T (T)of the template. Which of the following represents the primer sequence?

Introduction: Evolution and Themes of Biology

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

Cell Communication

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

From Gene to Protein

Regulation of Gene Expression

Viruses

Dna Tools and Biotechnology

Genomes and Their Evolution

Descent With Modification: a Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity Ii: the Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signalling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behaviour

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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