Question 1

Which of the following is NOT one of the four criteria that genetic material must fulfill to function in living organisms?

Accepted Answer

It must be able to catalyze metabolic reactions.

Question 2

In Griffith's experiment with Streptococcus pneumoniae, what was the key observation that led to the concept of the 'transforming principle'?

Accepted Answer

Type R bacteria became virulent after being mixed with heat-killed type S bacteria.

Question 3

Avery, MacLeod, and McCarty's experiments provided evidence that DNA is the genetic material by showing that:

Accepted Answer

Only DNA, not proteins or carbohydrates, could transform non-virulent bacteria into virulent forms.

Question 4

Which result from the Hershey and Chase experiment most strongly supported DNA as the genetic material?

Accepted Answer

Radioactive phosphorus ($^{32}P$) entered the bacterial cells, while radioactive sulfur ($^{35}S$) remained outside.

Question 5

Which of the following correctly describes the structure of a nucleotide found in DNA?

Accepted Answer

A phosphate group, deoxyribose sugar, and a nitrogenous base

Question 6

Which of the following is a key structural difference between DNA and RNA nucleotides?

Accepted Answer

DNA contains deoxyribose and thymine, while RNA contains ribose and uracil.

Question 7

Which statement best describes the antiparallel nature of the DNA double helix?

Accepted Answer

The two strands run in opposite directions: one 5' to 3', the other 3' to 5'.

Question 8

Which of the following base pairing rules applies to the DNA double helix?

Accepted Answer

A pairs with T, and G pairs with C

Question 9

If a DNA molecule contains 30% adenine, what percentage of guanine would you expect according to Chargaff's rules?

Accepted Answer

20%

Question 10

Which experimental technique was crucial for Watson and Crick to deduce the double helical structure of DNA?

Accepted Answer

X-ray diffraction

Question 11

What is the approximate number of base pairs per complete turn of the DNA double helix?

Accepted Answer

$10$

Question 12

Which of the following best describes the backbone of a DNA strand?

Accepted Answer

Alternating sugar and phosphate groups linked by phosphodiester bonds

Question 13

Which feature is unique to RNA compared to DNA?

Accepted Answer

RNA contains uracil instead of thymine.

Question 14

Which of the following is a real-world application of the discovery that DNA is the genetic material?

Accepted Answer

Development of DNA-based forensic identification techniques

Question 15

Which of the following statements about the directionality of DNA strands is correct?

Accepted Answer

One strand runs 5' to 3', and the other runs 3' to 5'.

Question 16

Which of the following is a correct description of a phosphodiester bond in nucleic acids?

Accepted Answer

A bond between the 5' phosphate group of one nucleotide and the 3' hydroxyl group of another

Question 17

Which of the following is NOT a structural feature of the DNA double helix?

Accepted Answer

Left-handed helical twist

Question 18

Which of the following best explains why DNA, and not protein, was identified as the genetic material in the Hershey-Chase experiment?

Accepted Answer

DNA entered the bacterial cells and directed the production of new phages.

Question 19

Which of the following is a correct statement about the secondary structure of RNA?

Accepted Answer

RNA can form bulge loops, internal loops, and multibranch junctions.

Question 20

A scientist isolates a nucleic acid from a cell and finds it contains ribose and uracil. Which type of nucleic acid is this most likely to be?

Accepted Answer

RNA

Molecular Structure of DNA and RNA: Foundations and Key Experiments

Study Guide - Practice Questions