Question 1

Which experiment provided definitive evidence that DNA, and not protein, is the genetic material in phages infecting bacteria?

Accepted Answer

Alfred Hershey and Martha Chase's radioactive labeling experiment

Question 2

According to Chargaff’s rules, if a DNA sample contains 30% adenine, what percentage of guanine would you expect?

Accepted Answer

20%

Question 3

Which structural feature of DNA ensures that the molecule has a uniform width, as observed in X-ray crystallography?

Accepted Answer

Pairing of a purine with a pyrimidine

Question 4

What is the function of helicase during DNA replication?

Accepted Answer

Unwinds the parental double helix at replication forks

Question 5

During DNA replication, why is the lagging strand synthesized in fragments?

Accepted Answer

The lagging strand template runs in the 5' → 3' direction, requiring synthesis away from the replication fork

Question 6

Which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

DNA ligase

Question 7

If a mutation occurs during DNA replication and is not repaired, what is the evolutionary significance?

Accepted Answer

It can be passed to the next generation and contribute to genetic variation

Question 8

Which of the following best describes the semiconservative model of DNA replication?

Accepted Answer

Each daughter DNA molecule consists of one old strand and one new strand

Question 9

What is the role of topoisomerase during DNA replication?

Accepted Answer

Relieves overwinding strain ahead of replication forks by breaking, swiveling, and rejoining DNA strands

Question 10

Which chemical reaction is responsible for the addition of nucleotides to a growing DNA strand?

Accepted Answer

Dehydration synthesis

Question 11

A DNA strand is synthesized in which direction?

Accepted Answer

5' → 3'

Question 12

Which protein binds to and stabilizes single-stranded DNA until it can be used as a template?

Accepted Answer

Single-strand binding protein

Question 13

What is the function of primase during DNA replication?

Accepted Answer

Synthesizes short RNA primers

Question 14

Which of the following is NOT a function of DNA polymerase I?

Accepted Answer

Synthesizes the leading strand continuously

Question 15

In nucleotide excision repair, which enzyme is responsible for cutting out damaged stretches of DNA?

Accepted Answer

Nuclease

Question 16

Which of the following best describes the structure of a nucleosome?

Accepted Answer

DNA wound twice around a core of eight histones

Question 17

What is the effect of histone modifications on chromatin?

Accepted Answer

They result in changes in chromatin condensation and can regulate gene expression

Question 18

Which type of chromatin is loosely packed and accessible for gene expression during interphase?

Accepted Answer

Euchromatin

Question 19

A bacterial chromosome is typically:

Accepted Answer

Circular and associated with a small amount of protein

Question 20

Which equation represents the relationship between the number of adenine and thymine bases in DNA, according to Chargaff’s rules?

Accepted Answer

$$A = T$$

Chapter 16: The Molecular Basis of Inheritance – DNA Structure, Replication, and Chromosome Organization

Study Guide - Practice Questions