Question 1

Which of the following is NOT a characteristic of hereditary material as described in modern genetics?

Accepted Answer

It is unable to replicate itself accurately.

Question 2

Frederick Griffith’s experiment with Pneumococcus bacteria provided evidence for which genetic process?

Accepted Answer

Transformation

Question 3

Which experiment provided direct evidence that DNA is the hereditary material?

Accepted Answer

Avery, MacLeod, and McCarty’s in vitro transformation experiment

Question 4

In the Hershey-Chase experiment, what was the key finding that demonstrated DNA is the genetic material?

Accepted Answer

Radioactive phosphorus was found inside the bacteria.

Question 5

Which of the following best describes the structure of the DNA double helix?

Accepted Answer

Two antiparallel strands with complementary base pairing

Question 6

What is the significance of the major and minor grooves in the DNA double helix?

Accepted Answer

They are regions where DNA-binding proteins can interact with nucleotides.

Question 7

Which form of DNA is most commonly found in living cells?

Accepted Answer

B-form

Question 8

Which model of DNA replication was supported by the Meselson-Stahl experiment?

Accepted Answer

Semiconservative

Question 9

During DNA replication in E. coli, which enzyme is responsible for unwinding the DNA helix?

Accepted Answer

DnaB helicase

Question 10

What is the role of RNA primers in DNA replication?

Accepted Answer

They provide a 3' hydroxyl group for DNA polymerase to begin synthesis.

Question 11

Which enzyme removes RNA primers and replaces them with DNA nucleotides during replication in E. coli?

Accepted Answer

DNA polymerase I

Question 12

Why is the lagging strand synthesized discontinuously during DNA replication?

Accepted Answer

Because DNA polymerase can only add nucleotides to the 3' end and the fork opens in the opposite direction

Question 13

What is the function of the sliding clamp in DNA replication?

Accepted Answer

It anchors DNA polymerase to the template strand, increasing processivity.

Question 14

Which enzyme relieves supercoiling ahead of the replication fork?

Accepted Answer

Topoisomerase

Question 15

What is the main limitation of PCR (Polymerase Chain Reaction)?

Accepted Answer

It requires prior knowledge of the target DNA sequence for primer design.

Question 16

In Sanger sequencing, what is the role of dideoxynucleotides (ddNTPs)?

Accepted Answer

They terminate DNA strand elongation at specific bases.

Question 17

Which of the following best explains why telomeres are important for chromosome stability?

Accepted Answer

They prevent the loss of important genetic information during DNA replication.

Question 18

What is the Hayflick limit?

Accepted Answer

The number of cell divisions a vertebrate cell can undergo before apoptosis due to telomere shortening

Question 19

Which of the following is a key advantage of next-generation sequencing (NGS) over Sanger sequencing?

Accepted Answer

NGS can sequence millions of DNA fragments in parallel, increasing speed and reducing cost.

Question 20

A mutation in the gene encoding DNA polymerase’s 3' to 5' exonuclease activity would most likely result in:

Accepted Answer

Increased mutation rate due to loss of proofreading

DNA Structure and Replication: Key Concepts and Experiments

Study Guide - Practice Questions