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Question 1
Which statement best describes the proofreading capability of DNA polymerases in prokaryotes?
Correct Answer:
DNA polymerase II alone provides proofreading
Explanation:
Proofreading during prokaryotic DNA replication relies on 3'→5' exonuclease activity to remove mismatched nucleotides as synthesis occurs. The primary copying enzyme, DNA polymerase III, provides most of this proofreading through its exonuclease function, greatly boosting fidelity. DNA polymerase I also has 3'→5' exonuclease proofreading, though its main roles are removing RNA primers and filling in gaps after Okazaki fragments rather than bulk synthesis. DNA polymerase II does have proofreading capability, but it is mainly involved in DNA repair rather than serving as the sole replicative proofreading enzyme. So proofreading in bacteria is a collaborative effort, with Pol III doing the bulk of it and Pol I contributing, while Pol II offers an additional, supportive role rather than being the sole source of proofreading.
Question 2
Okazaki fragments are produced on which strand?
Correct Answer:
Lagging strand
Explanation:
DNA polymerase can only add nucleotides in the 5' to 3' direction. Because the two DNA strands run antiparallel, the strand oriented 3' to 5' toward the fork must be copied in short bursts as the fork opens. These short, newly made pieces are called Okazaki fragments. The other strand runs 5' to 3' toward the fork, so it can be synthesized continuously as the fork advances. Primase lays down RNA primers for each fragment, and later DNA ligase joins the fragments into a continuous strand. So Okazaki fragments form on the lagging strand, not the leading strand, and the terms template or coding strand are more relevant to transcription than to this replication concept.
Question 3
Which activity provides proofreading during DNA synthesis?
Correct Answer:
3'→5' exonuclease activity of DNA polymerases.
Explanation:
Proofreading during DNA synthesis is carried out by the 3'→5' exonuclease activity of DNA polymerases. As nucleotides are added in the 5'→3' direction, the polymerase checks the newly added base; if a mismatch is detected, its 3' end is resected by the exonuclease domain, removing the incorrect nucleotide and a few preceding ones if needed. This allows the polymerase to reinsert the correct base and continue synthesis with high fidelity. In contrast, the 5'→3' exonuclease activity is mainly used to remove RNA primers or perform nick translation rather than proofreading the nascent strand. Mismatch repair operates after replication to fix errors on the newly synthesized strand, not during synthesis itself. Topoisomerase relieves torsional strain from supercoiling and does not participate in proofreading.
Question 4
The DNA that remains largely noncoding and repetitive constitutes the majority of the genome.
Correct Answer:
Repetitive DNA
Explanation:
Many organisms have most of their DNA not encoding proteins. The bulk of the genome is made up of noncoding, repetitive sequences such as transposable elements, satellite DNA, and simple sequence repeats. These repetitive elements can exist in many copies, filling up the genome and making noncoding DNA the majority. Only a small fraction of the genome codes for proteins, and the genes that are transcribed into messenger RNA come from those coding regions. So the description points to repetitive DNA as the predominant component of the genome.
Question 5
During which specific phase of interphase is DNA replicated?
Correct Answer:
S Phase
Explanation:
DNA replication happens during the S phase of interphase. During this phase, the cell duplicates its entire genome, producing sister chromatids for each chromosome that stay connected at the centromere until mitosis. This doubling of DNA content ensures that, when the cell eventually divides, each daughter cell receives an identical set of chromosomes. The other interphase phases are for growth and preparation (G1 and G2), while mitosis (M phase) is when chromosomes are separated, not replicated.
Question 1
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About this Exam

Prepare with the DNA Replication and DNA Storage Practice Test practice quiz. This question bank includes 10 questions covering replication, proofreading, strand, primer, and exonuclease. Use it to review important concepts, identify knowledge gaps, and build confidence for the related exam, course, or assessment.

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DNA Replication and DNA Storage Practice Test

This practice set contains 10 questions from the matching question bank and focuses on replication, proofreading, strand, primer, and exonuclease. Work through each question carefully, review the provided solutions, and revisit topics that need more study before your next attempt.

This is an independent study resource intended for practice and review; it is not an official examination or an endorsement by any organization named in the title.

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