Question 1

Which enzyme is responsible for unwinding the DNA double helix during DNA replication, as shown in the first image?

Accepted Answer

Helicase

Question 2

What is the primary function of single-stranded binding proteins during DNA replication?

Accepted Answer

They prevent the separated DNA strands from re-annealing.

Question 3

During DNA replication, what is the significance of 'replication bubbles' as depicted in the second and fifth images?

Accepted Answer

They are sites where DNA is being replicated simultaneously at multiple locations.

Question 4

Which enzyme adds RNA primers to the DNA template during replication, as shown in the third image?

Accepted Answer

Primase

Question 5

What is the role of DNA polymerase during DNA replication?

Accepted Answer

It adds new nucleotides to the growing DNA strand based on the template strand.

Question 6

Why is DNA replication described as 'semi-conservative'?

Accepted Answer

Each new DNA molecule contains one original strand and one newly synthesized strand.

Question 7

Which strand is synthesized continuously during DNA replication, as shown in the fourth image?

Accepted Answer

Leading strand

Question 8

What are Okazaki fragments, and on which strand do they form?

Accepted Answer

Short DNA fragments formed on the lagging strand

Question 9

Which enzyme is responsible for joining Okazaki fragments together during DNA replication?

Accepted Answer

Ligase

Question 10

A mutation occurs during DNA replication. Which sequence of enzyme activities is most likely involved in repairing this mutation?

Accepted Answer

Read enzymes → Cut enzymes → Replace enzymes

Question 11

If a cell fails to repair a mutation before mitosis, what is a possible consequence?

Accepted Answer

The mutation may be passed on to daughter cells, potentially affecting cell function.

Question 12

Which of the following best describes the direction of DNA synthesis on the leading and lagging strands?

Accepted Answer

Both strands are synthesized in the 5' to 3' direction.

Question 13

A scientist exposes cells to a chemical that inhibits ligase activity. What is the most likely effect on DNA replication?

Accepted Answer

Okazaki fragments on the lagging strand will not be joined together.

Question 14

Which of the following is a correct complementary base pairing in DNA replication?

Accepted Answer

Cytosine pairs with Guanine

Question 15

During which phase of the cell cycle does DNA replication occur?

Accepted Answer

S phase

Question 16

Which of the following best explains why multiple replication bubbles form during DNA replication in eukaryotic cells?

Accepted Answer

To increase the rate of DNA replication and ensure the entire genome is copied efficiently.

Question 17

A patient is exposed to high levels of radiation, which causes DNA damage. Which repair mechanism is most likely to be activated?

Accepted Answer

Specialized DNA repair enzymes will recognize, remove, and replace damaged nucleotides.

Question 18

Which of the following equations best represents the semi-conservative model of DNA replication?

Accepted Answer

$$	ext{Parent DNA} ightarrow 	ext{Daughter DNA}_1 + 	ext{Daughter DNA}_2 ($$each with one old and one new strand)

Question 19

If DNA polymerase makes a mistake during replication, which enzyme is responsible for recognizing and removing the incorrect nucleotide?

Accepted Answer

Cut enzyme

Question 20

Which of the following best describes the overall time required for DNA replication in a typical human cell?

Accepted Answer

About 7–8 hours

DNA Replication and Repair: Human Biology Study Notes

Study Guide - Practice Questions