Question 1

Which of the following best describes the difference between a nucleoside and a nucleotide?

Accepted Answer

A nucleoside contains a nitrogenous base and a sugar, while a nucleotide contains a nitrogenous base, a sugar, and one or more phosphate groups.

Question 2

Which of the following is found only in DNA and not in RNA?

Accepted Answer

Thymine

Question 3

What is the main reason DNA is more stable than RNA under physiological conditions?

Accepted Answer

DNA lacks a 2'-OH group, preventing nucleophilic attack and cleavage.

Question 4

Which of the following sequences is complementary to the DNA strand (5')-TATGCAT-(3')?

Accepted Answer

(3')-ATACGTA-(5')

Question 5

During DNA replication, which direction is the new strand synthesized?

Accepted Answer

5' to 3'

Question 6

Which of the following best explains why thymine is used in DNA instead of uracil?

Accepted Answer

Cytosine can be deaminated to uracil, so using thymine allows cells to recognize and repair mutations.

Question 7

Which enzyme is responsible for attaching an amino acid to its corresponding tRNA during translation?

Accepted Answer

Aminoacyl-tRNA synthetase

Question 8

What is the role of cyclic AMP (cAMP) in cellular signaling?

Accepted Answer

It acts as a second messenger, relaying signals from hormones to enzymes.

Question 9

Which of the following statements about restriction enzymes is correct?

Accepted Answer

They cleave DNA at specific palindromic sequences.

Question 10

Which of the following best describes the backbone of a DNA double helix?

Accepted Answer

It consists of alternating sugar and phosphate groups on the outside of the helix.

Question 11

Which of the following is a correct description of the process of transcription?

Accepted Answer

RNA is synthesized from a DNA template, with uracil replacing thymine.

Question 12

Which of the following best explains why hydrolysis of pyrophosphate drives the formation of nucleic acids?

Accepted Answer

Hydrolysis of pyrophosphate makes the nucleotide addition reaction irreversible.

Question 13

Which of the following is a real-world application of genetic engineering described in the study materials?

Accepted Answer

Plants are engineered to inactivate the active ingredient in herbicides.

Question 14

Which of the following best describes the function of messenger RNA (mRNA)?

Accepted Answer

It carries the genetic code from DNA to the ribosome for protein synthesis.

Question 15

Which of the following is the correct sequence of events in the central dogma of molecular biology?

Accepted Answer

DNA → RNA → Protein

Question 16

Which of the following statements about hydrogen bonding in DNA is correct?

Accepted Answer

Adenine pairs with thymine via two hydrogen bonds, and guanine pairs with cytosine via three hydrogen bonds.

Question 17

Which of the following best explains the importance of the 5' and 3' ends in nucleic acid synthesis?

Accepted Answer

Nucleotides are always added to the 3' end of the growing chain.

Question 18

Which of the following is a plausible consequence if DNA contained uracil instead of thymine?

Accepted Answer

It would be difficult for the cell to distinguish between cytosine deamination and normal uracil, leading to increased mutation rates.

Question 19

Which of the following best describes the function of restriction enzymes in molecular biology?

Accepted Answer

They cleave DNA at specific sequences, enabling genetic engineering and DNA analysis.

The Chemistry of Nucleic Acids: Structure, Function, and Mechanisms

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