IB Diploma Programme (DP) - SL & HL · Biology

D1.1 DNA replication (Molecules): Practice Questions

3 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on D1.1 DNA replication (Molecules).

8 questions29 marksFree, no account

Question 1

1 mark

In humans, telomeres are repetitive DNA sequences at the ends of chromosomes. Which of the following statements best explains the role of telomeres and the enzyme telomerase in cellular processes?

Question 2

1 mark

During DNA replication, DNA polymerase III is responsible for adding nucleotides to the growing strand. However, errors can occur. Which of the following mechanisms primarily contributes to the high fidelity of DNA replication in preventing and correcting these errors?

Question 3

1 mark

The lagging strand during DNA replication is synthesized discontinuously. Which combination of enzymes is directly involved in the synthesis and eventual joining of these discontinuous segments, known as Okazaki fragments?

Question 4

3 marks

Explain why DNA replication is considered semi-conservative.

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Question 5

5 marks

Differentiate between the functions of DNA polymerase III and DNA polymerase I during prokaryotic DNA replication.

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Question 6

3 marks

Explain why the enzyme DNA primase is essential for the initiation of DNA synthesis by DNA polymerase III.

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Question 7

7 marks

Describe the semi-conservative process of DNA replication, outlining the specific roles of the following enzymes and proteins: DNA helicase, DNA gyrase (topoisomerase), single-strand binding proteins, DNA primase, DNA polymerase III, DNA polymerase I, and DNA ligase. Explain how the leading and lagging strands are synthesized differently and why this difference is necessary.

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Question 8

8 marks

The process of DNA replication involves a series of highly coordinated steps to ensure the entire genome is copied accurately before cell division. This complexity arises from both the chemical structure of the DNA molecule and the specific requirements of the enzymes involved.

a) During replication, the double helix must be stabilized after it is unwound. Explain the importance of single-strand binding proteins (SSBs) in preventing the re-annealing of DNA and protecting the exposed bases from enzymatic degradation.
b) Describe the biochemical reaction that provides the energy for the formation of a phosphodiester bond, including the specific role of deoxynucleoside triphosphates (dNTPs) and the byproduct (\(PP_i\)) released during the process.
c) Explain why the discontinuous synthesis of the lagging strand is an inevitable consequence of the antiparallel structure of the DNA double helix combined with the specific directionality requirements (addition to the \(3'\) end) of DNA polymerase III.

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