Question 1

Which experiment provided the final confirmation that DNA is the genetic material responsible for transformation in bacteria?

Accepted Answer

Alfred Hershey and Martha Chase's experiment using bacteriophages

Question 2

In the Avery-MacLeod-McCarty experiment, which enzyme treatment prevented transformation, indicating the genetic material was DNA?

Accepted Answer

Deoxyribonuclease (DNase)

Question 3

Which of the following is a purine base found in DNA?

Accepted Answer

Adenine

Question 4

What is the main structural difference between ribose and deoxyribose sugars in nucleic acids?

Accepted Answer

Deoxyribose lacks an oxygen atom at the 2' carbon

Question 5

According to the Watson-Crick model, how many base pairs are there per complete turn of the DNA double helix?

Accepted Answer

$$10$$

Question 6

Which of the following best describes the directionality of the two DNA strands in the double helix?

Accepted Answer

The strands are antiparallel, one runs 5' to 3' and the other 3' to 5'

Question 7

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Question 8

What is the function of DNA gyrase during DNA replication?

Accepted Answer

It introduces negative supercoils ahead of the replication fork

Question 9

Why are Okazaki fragments shorter in eukaryotes than in prokaryotes?

Accepted Answer

Eukaryotic DNA synthesis is slower due to nucleosome rearrangement

Question 10

Which of the following equations correctly represents the number of hydrogen bonds between base pairs in DNA?

Accepted Answer

$$A-T$$ pairs have 2 hydrogen bonds, $$G-C$$ pairs have 3 hydrogen bonds

Question 11

During semiconservative replication, what is the composition of the two resulting DNA molecules?

Accepted Answer

Each contains one old and one new strand

Question 12

Which of the following best explains why multiple origins of replication are necessary in eukaryotic chromosomes?

Accepted Answer

Eukaryotic chromosomes are linear and very large

Question 13

Which of the following is NOT a characteristic required of genetic material?

Accepted Answer

Ability to catalyze metabolic reactions

Question 14

A mutation changes a cytosine to a thymine in a DNA strand. Which type of base pairing is disrupted?

Accepted Answer

Pyrimidine-purine

Question 15

Which of the following best describes the role of single-strand binding proteins during DNA replication?

Accepted Answer

They prevent reannealing of separated DNA strands

Question 16

If a DNA molecule is 340 Å long, how many complete turns does it contain according to the Watson-Crick model?

Accepted Answer

$$340 \div 34 = 10$$ turns

Question 17

Which of the following is a correct sequence of events during the lytic cycle of a bacteriophage, as shown in the Hershey-Chase experiment?

Accepted Answer

Attachment, injection of DNA, replication of DNA, assembly and release of new phages

Question 18

Which of the following statements about phosphodiester bonds in DNA is correct?

Accepted Answer

They connect the 3' carbon of one sugar to the 5' phosphate of the next

Question 19

Which of the following best explains why DNA polymerase requires an RNA primer to initiate synthesis?

Accepted Answer

DNA polymerase can only add nucleotides to an existing 3' hydroxyl group

Genetic Material: Structure, Chemistry, and Replication

Study Guide - Practice Questions