Question 1

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

Accepted Answer

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

Question 2

Which nitrogenous base is NOT found in DNA?

Accepted Answer

Uracil

Question 3

If a DNA molecule contains 30% adenine, what percentage of thymine would you expect to find?

Accepted Answer

$30\%$

Question 4

Which type of bond connects the nitrogenous bases in the DNA double helix?

Accepted Answer

Hydrogen bond

Question 5

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

Accepted Answer

Adenine

Question 6

What is the main difference between DNA and RNA nucleotides?

Accepted Answer

DNA contains deoxyribose sugar, while RNA contains ribose sugar

Question 7

Which organelle contains its own DNA, separate from the nuclear DNA?

Accepted Answer

Chloroplast

Question 8

Which of the following best explains why DNA is considered a stable molecule for genetic information storage?

Accepted Answer

It has a double helix structure with complementary base pairing

Question 9

A mutation changes a cytosine to a thymine in a DNA strand. What type of base pairing will be affected?

Accepted Answer

The hydrogen bonding between cytosine and guanine

Question 10

Which of the following is the correct complementary base pairing in DNA?

Accepted Answer

Adenine pairs with Thymine, Cytosine pairs with Guanine

Question 11

Which chemical bond is responsible for holding the backbone of the DNA molecule together?

Accepted Answer

Phosphodiester bond

Question 12

If a DNA sample is found to have 18% guanine, what is the expected percentage of cytosine?

Accepted Answer

$18\%$

Question 13

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

Accepted Answer

Covalent bonds connect the sugar and phosphate groups in the DNA backbone

Question 14

Which of the following best describes the role of pentose sugar in DNA?

Accepted Answer

It forms part of the backbone, connecting to both phosphate and nitrogenous base

Question 15

Which of the following is a real-world consequence of a mutation in the DNA sequence of a chloroplast gene?

Accepted Answer

Impaired photosynthesis in plant cells

Question 16

A scientist isolates a molecule with the following components: a phosphate group, deoxyribose sugar, and thymine. What type of molecule is this?

Accepted Answer

A DNA nucleotide

Question 17

Which of the following is NOT a component of the DNA backbone?

Accepted Answer

Nitrogenous base

Question 18

Which of the following best explains why covalent bonds are important in the structure of DNA?

Accepted Answer

They provide stability to the backbone by connecting sugars and phosphates

Question 19

Which of the following scenarios would most likely result from a disruption in the hydrogen bonding between DNA bases?

Accepted Answer

The two DNA strands would separate more easily during replication

Question 20

Which of the following best describes the difference between purines and pyrimidines in DNA?

Accepted Answer

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

Nucleic Acids: Structure and Components

Study Guide - Practice Questions