Question 1

Which of the following correctly lists the four nitrogenous bases found in DNA?

Accepted Answer

Adenine, Thymine, Cytosine, Guanine

Question 2

Which sugar is found in RNA, and how does its structure differ from the sugar in DNA?

Accepted Answer

Ribose; it has a hydroxyl group at the 2' carbon, while deoxyribose does not

Question 3

The central dogma of molecular biology describes the flow of genetic information. Which sequence correctly represents this process?

Accepted Answer

$DNA \rightarrow RNA \rightarrow Protein$

Question 4

When a new nucleotide is added to a growing DNA strand, which part of the incoming nucleotide forms a bond with the existing chain?

Accepted Answer

The 5' phosphate group of the incoming nucleotide binds to the 3' hydroxyl group of the existing chain

Question 5

Which of the following pairs correctly matches purines and pyrimidines found in DNA?

Accepted Answer

Purines: Adenine, Guanine; Pyrimidines: Cytosine, Thymine

Question 6

What is the name of the covalent bond that links two adjacent nucleotides in a DNA strand?

Accepted Answer

Phosphodiester bond

Question 7

Which type of bond holds together the complementary nitrogenous bases in the DNA double helix?

Accepted Answer

Hydrogen bond

Question 8

In a DNA double helix, which components of the nucleotides form the backbone of the molecule?

Accepted Answer

Phosphate and sugar groups

Question 9

Which of the following correctly describes the complementary base pairing in DNA?

Accepted Answer

Adenine pairs with Thymine; Guanine pairs with Cytosine

Question 10

Which of the following statements about the structure of purines and pyrimidines is correct?

Accepted Answer

Purines have a double ring structure, while pyrimidines have a single ring structure

Question 11

A mutation causes a thymine in DNA to be replaced by uracil. What type of molecule would this most likely affect?

Accepted Answer

It would affect DNA, since uracil is not normally found in DNA

Question 12

During DNA replication, which enzyme is responsible for forming the phosphodiester bonds between nucleotides?

Accepted Answer

DNA polymerase

Question 13

If a DNA strand has the sequence 5'-ATCG-3', what is the complementary sequence on the opposite strand?

Accepted Answer

3'-TAGC-5'

Question 14

Which of the following best explains why DNA is more stable than RNA?

Accepted Answer

DNA lacks a hydroxyl group at the 2' carbon, making it less susceptible to hydrolysis

Question 15

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

Accepted Answer

Amino acid

Question 16

In RNA, which nitrogenous base replaces thymine?

Accepted Answer

Uracil

Question 17

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

Accepted Answer

The strands run in opposite directions (antiparallel)

Question 18

A scientist is analyzing a DNA molecule and finds that 30% of its bases are adenine. What percentage of the bases are thymine?

Accepted Answer

30%

Question 19

Which of the following is the correct formula for the number of hydrogen bonds between complementary base pairs in DNA?

Accepted Answer

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

Question 20

Which of the following best describes the role of the phosphate group in the structure of nucleic acids?

Accepted Answer

It connects the 3' carbon of one sugar to the 5' carbon of the next via a phosphodiester bond

Ch 4 review

Study Guide - Practice Questions