Question 1

Which of the following criteria is NOT required for a molecule to serve as the genetic material in cells?

Accepted Answer

It must be able to form lipid bilayers.

Question 2

In Frederick Griffith’s classic experiment with Streptococcus pneumoniae, what was the key observation that led to the concept of transformation?

Accepted Answer

Living type R bacteria mixed with heat-killed type S bacteria killed the mice and type S bacteria were recovered.

Question 3

Avery, MacLeod, and McCarty demonstrated that DNA is the transforming principle by showing that:

Accepted Answer

Only DNA extracts could transform R cells into S cells, and this ability was destroyed by DNase.

Question 4

In the Hershey and Chase experiment, which isotope was used to label DNA, and why?

Accepted Answer

$$^{32}\mathrm{P}$$, because DNA contains phosphorus but not sulfur.

Question 5

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

Accepted Answer

A phosphate group, a deoxyribose sugar, and a nitrogenous base

Question 6

Which of the following statements about the Watson and Crick model of DNA is FALSE?

Accepted Answer

The sugar-phosphate backbone is on the inside of the helix.

Question 7

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

Accepted Answer

20%

Question 8

Which feature distinguishes Z-DNA from B-DNA?

Accepted Answer

Z-DNA is left-handed, while B-DNA is right-handed.

Question 9

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

Accepted Answer

A bond between the 5’ phosphate of one nucleotide and the 3’ hydroxyl of another.

Question 10

Which of the following best explains why RNA can form complex secondary structures such as hairpins and bulges?

Accepted Answer

RNA can base-pair with itself due to complementary sequences within the same strand.

Question 11

A scientist isolates a virus and finds that its genome is composed of RNA. Which experiment from the history of genetics does this finding most closely relate to?

Accepted Answer

Gierer and Schramm’s work with tobacco mosaic virus

Question 12

Which of the following is TRUE regarding the major and minor grooves of DNA?

Accepted Answer

The major groove is the primary site for protein binding and sequence recognition.

Question 13

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

Accepted Answer

It has a 5’ to 3’ directionality due to the orientation of the sugar-phosphate backbone.

Question 14

Which of the following is NOT a component of a nucleoside?

Accepted Answer

Phosphate group

Question 15

Triplex DNA can form when:

Accepted Answer

A synthetic DNA strand binds to the major groove of a double-stranded DNA molecule.

Question 16

Which of the following is a real-world application of understanding the structure of DNA?

Accepted Answer

Forensic identification using DNA fingerprinting.

Question 17

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

Accepted Answer

Guanine-cytosine pairing, which involves three hydrogen bonds.

Question 18

Which of the following best explains why DNA, and not protein, was ultimately identified as the genetic material?

Accepted Answer

Only DNA was shown to transform non-virulent bacteria into virulent forms in classic experiments.

Question 19

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

Accepted Answer

DNA contains deoxyribose, while RNA contains ribose.

Question 20

Which of the following best describes the secondary structure of tRNA?

Accepted Answer

It forms a cloverleaf structure with both single- and double-stranded regions.

The Molecular Basis of Heredity: Structure and Function of Genetic Material

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