Question 1

Which of the following best describes the general function of DNA in a cell?

Accepted Answer

DNA stores and transmits genetic information required for protein synthesis and cell function.

Question 2

Which components form the backbone of a DNA strand?

Accepted Answer

Phosphate groups and deoxyribose sugars

Question 3

Which type of bond connects the nitrogenous bases of complementary DNA strands?

Accepted Answer

Hydrogen bonds

Question 4

Given the DNA sequence 5'-A G T T C A G C T-3', what is the complementary strand?

Accepted Answer

3'-T C A A G T C G A-5'

Question 5

What functional group is found at the 5’ end of a DNA strand?

Accepted Answer

Phosphate group

Question 6

Why is the 3’ end of a DNA strand crucial during DNA replication?

Accepted Answer

It provides a free hydroxyl group for the addition of new nucleotides.

Question 7

What did Griffith’s experiment demonstrate?

Accepted Answer

Genetic information can be transferred between organisms, transforming their phenotype.

Question 8

What is meant by 'semiconservative replication'?

Accepted Answer

Each new DNA molecule consists of one parental and one newly synthesized strand.

Question 9

Which enzyme is responsible for relieving the strain ahead of the replication fork during DNA replication?

Accepted Answer

Topoisomerase

Question 10

Why is the lagging strand synthesized discontinuously?

Accepted Answer

The lagging strand template is oriented in the 5’ to 3’ direction away from the replication fork, requiring synthesis in short fragments.

Question 11

Which enzyme removes RNA primers and replaces them with DNA nucleotides during replication?

Accepted Answer

DNA polymerase I

Question 12

What is the role of DNA ligase in DNA replication?

Accepted Answer

It joins Okazaki fragments by forming phosphodiester bonds.

Question 13

Which of the following best describes the difference between DNA replication in cells and PCR in the laboratory?

Accepted Answer

DNA replication copies the entire genome, while PCR amplifies a specific DNA region.

Question 14

A DNA sample contains 27% adenine. According to Chargaff’s rule, what percentage of guanine is present?

Accepted Answer

$$G = 23\%$$

Question 15

Which of the following is a common real-world application of PCR?

Accepted Answer

Crime scene DNA analysis

Question 16

Which of the following statements about Okazaki fragments is correct?

Accepted Answer

They are short DNA fragments synthesized on the lagging strand.

Question 17

Which enzyme is responsible for synthesizing the RNA primer during DNA replication?

Accepted Answer

Primase

Question 18

During DNA replication, which direction does DNA polymerase III synthesize the new DNA strand?

Accepted Answer

5’ to 3’

Question 19

Which of the following best explains why DNA polymerase III has proofreading ability?

Accepted Answer

It can remove incorrectly paired nucleotides and replace them with the correct ones.

Question 20

A scientist wants to amplify a specific gene from a bacterial sample. Which ingredients must be present in the PCR reaction?

Accepted Answer

Template DNA, DNA primers, Taq DNA polymerase, nucleotides (dNTPs)

DNA Replication: Structure, Function, and Mechanisms

Study Guide - Practice Questions