BIOL101 Module 4 Quiz Bank
Essential Biology I w/Lab | 100 Multiple
Choice Questions with Explanations
SECTION A: DNA & RNA STRUCTURE (Questions 1–15)
Question 1
A nitrogenous base plus a deoxyribose sugar is called a ________,
and a base plus deoxyribose plus a phosphate group is called a
________.
A) Nucleotide; Nucleoside
B) Nucleoside; Nucleotide
C) Chromatin; Chromosome
D) Codon; Anticodon
Correct Answer: B) Nucleoside; Nucleotide
,Explanation: A nucleoside consists of a nitrogenous base
attached to a sugar (either ribose or deoxyribose) but lacks a
phosphate group. When a phosphate group is added to the
nucleoside, it becomes a nucleotide. Nucleotides are the
building blocks of nucleic acids like DNA and RNA.
Question 2
Which of the following nitrogenous bases are classified
as purines?
A) Cytosine and Thymine
B) Adenine and Guanine
C) Uracil and Cytosine
D) Thymine and Uracil
Correct Answer: B) Adenine and Guanine
Explanation: Purines are nitrogenous bases characterized by a
double-ring structure. Adenine (A) and Guanine (G) are the two
purines found in nucleic acids. Pyrimidines, in contrast, have a
single-ring structure and include Cytosine (C), Thymine (T), and
Uracil (U).
,Question 3
Which nitrogenous bases are classified as pyrimidines?
A) Adenine and Guanine
B) Cytosine, Thymine, and Uracil
C) Adenine and Thymine
D) Guanine and Cytosine
Correct Answer: B) Cytosine, Thymine, and Uracil
Explanation: Pyrimidines are nitrogenous bases with a single-
ring structure. Cytosine (C), Thymine (T), and Uracil (U) are all
pyrimidines. In DNA, the pyrimidines are cytosine and thymine;
in RNA, uracil replaces thymine.
Question 4
In DNA, adenine always pairs with:
A) Guanine
B) Cytosine
, C) Thymine
D) Uracil
Correct Answer: C) Thymine
Explanation: Complementary base pairing in DNA follows
Chargaff's rules: adenine (A) forms two hydrogen bonds with
thymine (T). This specific pairing is essential for accurate DNA
replication.
Question 5
In RNA, adenine always pairs with:
A) Thymine
B) Guanine
C) Cytosine
D) Uracil
Correct Answer: D) Uracil
Explanation: RNA contains uracil (U) instead of thymine (T).
During transcription, when RNA is synthesized from a DNA
Essential Biology I w/Lab | 100 Multiple
Choice Questions with Explanations
SECTION A: DNA & RNA STRUCTURE (Questions 1–15)
Question 1
A nitrogenous base plus a deoxyribose sugar is called a ________,
and a base plus deoxyribose plus a phosphate group is called a
________.
A) Nucleotide; Nucleoside
B) Nucleoside; Nucleotide
C) Chromatin; Chromosome
D) Codon; Anticodon
Correct Answer: B) Nucleoside; Nucleotide
,Explanation: A nucleoside consists of a nitrogenous base
attached to a sugar (either ribose or deoxyribose) but lacks a
phosphate group. When a phosphate group is added to the
nucleoside, it becomes a nucleotide. Nucleotides are the
building blocks of nucleic acids like DNA and RNA.
Question 2
Which of the following nitrogenous bases are classified
as purines?
A) Cytosine and Thymine
B) Adenine and Guanine
C) Uracil and Cytosine
D) Thymine and Uracil
Correct Answer: B) Adenine and Guanine
Explanation: Purines are nitrogenous bases characterized by a
double-ring structure. Adenine (A) and Guanine (G) are the two
purines found in nucleic acids. Pyrimidines, in contrast, have a
single-ring structure and include Cytosine (C), Thymine (T), and
Uracil (U).
,Question 3
Which nitrogenous bases are classified as pyrimidines?
A) Adenine and Guanine
B) Cytosine, Thymine, and Uracil
C) Adenine and Thymine
D) Guanine and Cytosine
Correct Answer: B) Cytosine, Thymine, and Uracil
Explanation: Pyrimidines are nitrogenous bases with a single-
ring structure. Cytosine (C), Thymine (T), and Uracil (U) are all
pyrimidines. In DNA, the pyrimidines are cytosine and thymine;
in RNA, uracil replaces thymine.
Question 4
In DNA, adenine always pairs with:
A) Guanine
B) Cytosine
, C) Thymine
D) Uracil
Correct Answer: C) Thymine
Explanation: Complementary base pairing in DNA follows
Chargaff's rules: adenine (A) forms two hydrogen bonds with
thymine (T). This specific pairing is essential for accurate DNA
replication.
Question 5
In RNA, adenine always pairs with:
A) Thymine
B) Guanine
C) Cytosine
D) Uracil
Correct Answer: D) Uracil
Explanation: RNA contains uracil (U) instead of thymine (T).
During transcription, when RNA is synthesized from a DNA
