Question 1

Which of the following statements about the origins of replication of DNA strands in eukaryotes is true?

Accepted Answer

A)  Eukaryote chromosomes have a single origin. 
B)  Origins are in histone-free areas of the chromosomes. 
C)  Replication is unidirectional from the origin. 
D)  Replication begins at the same time from multiple origins on the chromosome. 
E)  All of the statements are true. 
A)  Eukaryote chromosomes have a single origin. 
B)  Origins are in histone-free areas of the chromosomes. 
C)  Replication is unidirectional from the origin. 
D)  Replication begins at the same time from multiple origins on the chromosome. 
E)  All of the statements are true.

Question 2

The leading strand of DNA is

Accepted Answer

A)  the template for the two replicate strands of DNA. 
B)  synthesised continuously in the 5' to 3' direction. 
C)  synthesised discontinuously in the 3' to 5' direction. 
D)  synthesised continuously in the 3' to 5' direction. 
E)  the initiating sequence of DNA. 
A)  the template for the two replicate strands of DNA. 
B)  synthesised continuously in the 5' to 3' direction. 
C)  synthesised discontinuously in the 3' to 5' direction. 
D)  synthesised continuously in the 3' to 5' direction. 
E)  the initiating sequence of DNA.

Question 3

The 3' end of the newly synthesised DNA strand is where a

Accepted Answer

A)  hydroxyl group is attached to a ribose sugar. 
B)  phosphate group is attached to carbon 3 of the deoxyribose sugar. 
C)  hydroxyl group is attached to a nitrogenous base. 
D)  phosphate group is attached to carbon 3 of a nitrogenous base. 
E)  hydroxyl group is attached to carbon 3 of the deoxyribose sugar. 
A)  hydroxyl group is attached to a ribose sugar. 
B)  phosphate group is attached to carbon 3 of the deoxyribose sugar. 
C)  hydroxyl group is attached to a nitrogenous base. 
D)  phosphate group is attached to carbon 3 of a nitrogenous base. 
E)  hydroxyl group is attached to carbon 3 of the deoxyribose sugar.

Question 4

Which of the following statements in relation to DNA-dependent RNA polymerase is CORRECT?

Accepted Answer

A)  DNA-dependent RNA polymerase attaches nucleotides to a free 5' OH group. 
B)  DNA-dependent RNA polymerase must build an RNA strand from an existing strand. 
C)  DNA-dependent RNA polymerase can initiate RNA synthesis de novo on a DNA template. 
D)  DNA-dependent RNA polymerase initiates synthesis via the primorase enzyme. 
E)  DNA-dependent RNA polymerase uses a primer to terminate strand extension. 
A)  DNA-dependent RNA polymerase attaches nucleotides to a free 5' OH group. 
B)  DNA-dependent RNA polymerase must build an RNA strand from an existing strand. 
C)  DNA-dependent RNA polymerase can initiate RNA synthesis de novo on a DNA template. 
D)  DNA-dependent RNA polymerase initiates synthesis via the primorase enzyme. 
E)  DNA-dependent RNA polymerase uses a primer to terminate strand extension.

Question 5

What is the result of semiconservative replication?

Accepted Answer

A)  The generation of two semi-identical double helices. 
B)  The generation of a single double helix. 
C)  The generation of two identical daughter cells. 
D)  The generation of two identical double helices. 
E)  The generation of two identical transcripts. 
A)  The generation of two semi-identical double helices. 
B)  The generation of a single double helix. 
C)  The generation of two identical daughter cells. 
D)  The generation of two identical double helices. 
E)  The generation of two identical transcripts.

Question 6

What role does DNA gyrase play in DNA replication?

Accepted Answer

A)  All of the statements are true. 
B)  It facilitates the unwinding of the twists and supercoils of DNA. 
C)  It rejoins a cut phosphodiester bond. 
D)  It makes a transient cut in one strand of the DNA. 
E)  It adds negative supercoils to DNA. 
A)  All of the statements are true. 
B)  It facilitates the unwinding of the twists and supercoils of DNA. 
C)  It rejoins a cut phosphodiester bond. 
D)  It makes a transient cut in one strand of the DNA. 
E)  It adds negative supercoils to DNA.

Question 7

In prokaryotes, replication begins at the

Accepted Answer

A)  telomere. 
B)  origin. 
C)  terminus. 
D)  multiple replication sites. 
E)  centromere. 
A)  telomere. 
B)  origin. 
C)  terminus. 
D)  multiple replication sites. 
E)  centromere.

Question 8

Humans have 46 chromosomes. The most useful criteria for distinguishing the different chromosomes under the light microscope are

Accepted Answer

A)  the position of the centromere, and the length and banding pattern of the chromosomes. 
B)  the position of the telomere, and the size and banding pattern of the chromosomes. 
C)  the number of chromatids and the position of the centromere. 
D)  the number of telomeres and the length of the chromosomes. 
E)  the DNA content and the banding pattern of the chromosomes. 
A)  the position of the centromere, and the length and banding pattern of the chromosomes. 
B)  the position of the telomere, and the size and banding pattern of the chromosomes. 
C)  the number of chromatids and the position of the centromere. 
D)  the number of telomeres and the length of the chromosomes. 
E)  the DNA content and the banding pattern of the chromosomes.

Question 9

In DNA synthesis, primers

Accepted Answer

A)  are anti-parallel to the DNA strand that they pair with. 
B)  only occur on the lagging strand. 
C)  unwind the DNA. 
D)  supply starting points with 5' ends for DNA synthesis. 
E)  occur more often on the leading strand than on the lagging strand. 
A)  are anti-parallel to the DNA strand that they pair with. 
B)  only occur on the lagging strand. 
C)  unwind the DNA. 
D)  supply starting points with 5' ends for DNA synthesis. 
E)  occur more often on the leading strand than on the lagging strand.

Question 10

Which of the following statements about eukaryotic chromosomes is CORRECT?

Accepted Answer

A)  The DNA of eukaryotes consists of two strands each composed of a ribose sugar, a phosphate group and four nitrogen-containing bases. 
B)  Eukaryote chromosomes are comprised primarily of DNA condensed around histone proteins and interacting with other non-histone proteins. 
C)  Histone proteins assemble into groups around which the DNA coils to form a structure termed the nucleolus. 
D)  The ends of eukaryotic chromosomes contain a specific terminal sequence of RNA. 
E)  Histone proteins are small proteins with a high concentration of acidic residues which readily interact with the DNA. 
A)  The DNA of eukaryotes consists of two strands each composed of a ribose sugar, a phosphate group and four nitrogen-containing bases. 
B)  Eukaryote chromosomes are comprised primarily of DNA condensed around histone proteins and interacting with other non-histone proteins. 
C)  Histone proteins assemble into groups around which the DNA coils to form a structure termed the nucleolus. 
D)  The ends of eukaryotic chromosomes contain a specific terminal sequence of RNA. 
E)  Histone proteins are small proteins with a high concentration of acidic residues which readily interact with the DNA.

Question 11

Which of the following enzymes is NOT involved in the replication of prokaryotic DNA?

Accepted Answer

A)  DNA helicase 
B)  DNA polymerase 
C)  Primase 
D)  Telomerase 
E)  DNA ligase 
A)  DNA helicase 
B)  DNA polymerase 
C)  Primase 
D)  Telomerase 
E)  DNA ligase

Question 12

The main enzyme in DNA replication, DNA polymerase I also has a proof-reading exonuclease activity because it

Accepted Answer

A)  needs to remove the DNA primer so that synthesis may be completed. 
B)  needs to correct pre-existing errors in the DNA before it is replicated. 
C)  needs to remove small DNA strands before it can begin the synthesis of the new strand. 
D)  needs to replace incorrect nucleotides inserted into the newly-synthesised strand. 
E)  detects mutations caused by sunlight and is able to remove them. 
A)  needs to remove the DNA primer so that synthesis may be completed. 
B)  needs to correct pre-existing errors in the DNA before it is replicated. 
C)  needs to remove small DNA strands before it can begin the synthesis of the new strand. 
D)  needs to replace incorrect nucleotides inserted into the newly-synthesised strand. 
E)  detects mutations caused by sunlight and is able to remove them.

Question 13

Deoxyribonucleoside triphosphates (dNTPs) are the building blocks used in DNA synthesis. They are added to the strand of DNA being synthesised by

Accepted Answer

A)  the formation of a phosphodiester bond between the 2' dexoyribose on the growing strand and the phosphate of the incoming nucleotide. 
B)  the loss of two phosphates from dNTP. 
C)  the formation of a hydrogen bond with the 3' OH group of the newly synthesised DNA strand. 
D)  the formation of a phosphodiester bond between the nitrogenous base of one nucleotide and the phosphate group of another. 
E)  the action of the enzyme RNA polymerase. 
A)  the formation of a phosphodiester bond between the 2' dexoyribose on the growing strand and the phosphate of the incoming nucleotide. 
B)  the loss of two phosphates from dNTP. 
C)  the formation of a hydrogen bond with the 3' OH group of the newly synthesised DNA strand. 
D)  the formation of a phosphodiester bond between the nitrogenous base of one nucleotide and the phosphate group of another. 
E)  the action of the enzyme RNA polymerase.

Question 14

A colony of actively dividing bacteria (prokaryotes) is given radioactive thymine. If a cell then replicates its chromosome and divides once, which of the following outcomes would you expect?

Accepted Answer

A)  Radioactive DNA would be found in neither daughter cell. 
B)  All DNA and RNA bases in daughter cells would be radioactive. 
C)  Radioactive RNA would be found in both daughter cells. 
D)  Radioactive DNA would be found in both daughter cells. 
E)  Radioactive DNA would only be found in half of the daughter cells. 
A)  Radioactive DNA would be found in neither daughter cell. 
B)  All DNA and RNA bases in daughter cells would be radioactive. 
C)  Radioactive RNA would be found in both daughter cells. 
D)  Radioactive DNA would be found in both daughter cells. 
E)  Radioactive DNA would only be found in half of the daughter cells.

Question 15

A new strand of DNA is synthesised using an old strand as a template. In the process

Accepted Answer

A)  nucleotides are added onto the 3' end of the strand being synthesised. 
B)  nucleotides are added by the enzyme-catalysed formation of a bond between the 3'-phosphate of the incoming nucleotide and the 5' OH at the end of the strand. 
C)  a peptide bond is formed between each nucleotide. 
D)  the nucleotide sequence is determined by the concentration of the various nucleotides available in the cell. 
E)  energy for the addition for each nucleotide is supplied by ATP. 
A)  nucleotides are added onto the 3' end of the strand being synthesised. 
B)  nucleotides are added by the enzyme-catalysed formation of a bond between the 3'-phosphate of the incoming nucleotide and the 5' OH at the end of the strand. 
C)  a peptide bond is formed between each nucleotide. 
D)  the nucleotide sequence is determined by the concentration of the various nucleotides available in the cell. 
E)  energy for the addition for each nucleotide is supplied by ATP.

Question 16

In a classic experiment by Alfred Hershey and Martha Chase, DNA from a bacteriophage was labelled with radioactive 32P, while protein was labelled with 35S. Infected bacteria were found to contain most of the 32P but very little of the 35S. How does this experiment provide strong evidence for DNA being the molecule of inheritance?

Accepted Answer

A)  The result is confounding as DNA is bound to protein in the form of histones, meaning there should be equal amounts of both radioisotopes present. 
B)  Because DNA is present in higher concentration than protein in the host bacteria. 
C)  The results suggest it is DNA, not protein, being taken up by the host and passed from one generation to the next. 
D)  Because the proteins are more complex molecules than DNA they would be less likely to be transferred from one generation to the next. 
E)  All of the options listed here are incorrect. 
A)  The result is confounding as DNA is bound to protein in the form of histones, meaning there should be equal amounts of both radioisotopes present. 
B)  Because DNA is present in higher concentration than protein in the host bacteria. 
C)  The results suggest it is DNA, not protein, being taken up by the host and passed from one generation to the next. 
D)  Because the proteins are more complex molecules than DNA they would be less likely to be transferred from one generation to the next. 
E)  All of the options listed here are incorrect.

Question 17

Which of the following statements best describes the Polymerase Chain Reaction (PCR)?

Accepted Answer

A)  The process that repeatedly forms a polypeptide chain from a selected segment of DNA. 
B)  A reaction that synthesises a protein molecule from an RNA molecule. 
C)  A reaction that synthesises DNA from RNA. 
D)  A reaction in which RNA is hybridised to complementary DNA. 
E)  The process that repeatedly replicates a selected segment of DNA. 
A)  The process that repeatedly forms a polypeptide chain from a selected segment of DNA. 
B)  A reaction that synthesises a protein molecule from an RNA molecule. 
C)  A reaction that synthesises DNA from RNA. 
D)  A reaction in which RNA is hybridised to complementary DNA. 
E)  The process that repeatedly replicates a selected segment of DNA.

Question 18

In DNA synthesis, DNA helicases

Accepted Answer

A)  initiate the synthesis of the RNA primer. 
B)  help re-establish the coiled structure of DNA after replication. 
C)  break the hydrogen bonds between the nitrogenous bases. 
D)  help with the untwisting of the supercoils. 
E)  stabilise the separating DNA strands with proteins. 
A)  initiate the synthesis of the RNA primer. 
B)  help re-establish the coiled structure of DNA after replication. 
C)  break the hydrogen bonds between the nitrogenous bases. 
D)  help with the untwisting of the supercoils. 
E)  stabilise the separating DNA strands with proteins.

Question 19

If a section of the leading strand of DNA during replication has the sequence 5' TATCGGA 3', what would the sequence on an equivalent section of the lagging strand be?

Accepted Answer

A)  5' TATCGGA 3' 
B)  3' ATAGCCT 5' 
C)  5' UCCGAUA 3' 
D)  5' AUAGCCU 3' 
E)  3' TATCGGA 5' 
A)  5' TATCGGA 3' 
B)  3' ATAGCCT 5' 
C)  5' UCCGAUA 3' 
D)  5' AUAGCCU 3' 
E)  3' TATCGGA 5'

Question 20

If 20 per cent of the bases of a DNA double helix are adenine, what percentage of bases are cytosine?

Accepted Answer

A)  10 per cent 
B)  30 per cent 
C)  20 per cent 
D)  60 per cent 
E)  80 per cent 
A)  10 per cent 
B)  30 per cent 
C)  20 per cent 
D)  60 per cent 
E)  80 per cent

Exam 10: Genes, Chromosomes and Dna

Which of the following statements about the origins of replication of DNA strands in eukaryotes is true?

The leading strand of DNA is

The 3' end of the newly synthesised DNA strand is where a

Which of the following statements in relation to DNA-dependent RNA polymerase is CORRECT?

What is the result of semiconservative replication?

What role does DNA gyrase play in DNA replication?

In prokaryotes, replication begins at the

Humans have 46 chromosomes. The most useful criteria for distinguishing the different chromosomes under the light microscope are

In DNA synthesis, primers

Which of the following statements about eukaryotic chromosomes is CORRECT?

Which of the following enzymes is NOT involved in the replication of prokaryotic DNA?

The main enzyme in DNA replication, DNA polymerase I also has a proof-reading exonuclease activity because it

Deoxyribonucleoside triphosphates (dNTPs) are the building blocks used in DNA synthesis. They are added to the strand of DNA being synthesised by

A colony of actively dividing bacteria (prokaryotes) is given radioactive thymine. If a cell then replicates its chromosome and divides once, which of the following outcomes would you expect?

A new strand of DNA is synthesised using an old strand as a template. In the process

Which of the following statements best describes the Polymerase Chain Reaction (PCR)?

In DNA synthesis, DNA helicases

If a section of the leading strand of DNA during replication has the sequence 5' TATCGGA 3', what would the sequence on an equivalent section of the lagging strand be?

If 20 per cent of the bases of a DNA double helix are adenine, what percentage of bases are cytosine?

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