BIOD 210 Module 3 Exam – Genetics (Portage Learning) (2026) Actual Questions with Verified Answers |
Take & Pass the Exam
Questions 1–250
Section 1: DNA Structure and Organization (Questions 1–40)
1. The building blocks of DNA are:
A) Amino acids
B) Nucleotides
C) Monosaccharides
D) Fatty acids
Answer B: Nucleotides
Rationale: DNA is a polymer of nucleotides, each composed of a sugar, phosphate, and nitrogenous base.
2. A nucleotide in DNA consists of:
A) A phosphate group, a deoxyribose sugar, and a nitrogenous base
B) A phosphate group, a ribose sugar, and a nitrogenous base
C) A phosphate group, a deoxyribose sugar, and an amino acid
D) A sulfate group, a deoxyribose sugar, and a nitrogenous base
Answer A: A phosphate group, a deoxyribose sugar, and a nitrogenous base
Rationale: DNA nucleotides contain deoxyribose; RNA contains ribose.
3. Which of the following is NOT a nitrogenous base found in DNA?
A) Adenine
B) Guanine
C) Cytosine
D) Uracil
Answer D: Uracil
Rationale: Uracil is found in RNA; DNA contains thymine instead.
,4. The two strands of DNA are held together by:
A) Covalent bonds
B) Ionic bonds
C) Hydrogen bonds
D) Peptide bonds
Answer C: Hydrogen bonds
Rationale: Hydrogen bonds between complementary bases hold the two strands together.
5. In DNA, adenine pairs with:
A) Guanine
B) Cytosine
C) Thymine
D) Uracil
Answer C: Thymine
Rationale: A pairs with T via two hydrogen bonds.
6. In DNA, guanine pairs with:
A) Adenine
B) Cytosine
C) Thymine
D) Uracil
Answer B: Cytosine
Rationale: G pairs with C via three hydrogen bonds.
7. Chargaff's rules state that in DNA:
A) A = G and T = C
B) A = T and G = C
C) A = C and G = T
D) A + T = G + C
Answer B: A = T and G = C
Rationale: Complementary base pairing ensures A = T and G = C.
,8. The DNA double helix has:
A) Antiparallel strands
B) Parallel strands
C) Identical strands
D) Single-stranded regions
Answer A: Antiparallel strands
Rationale: The two strands run in opposite 5′→3′ directions.
9. The sugar in DNA is:
A) Ribose
B) Deoxyribose
C) Glucose
D) Fructose
Answer B: Deoxyribose
Rationale: Deoxyribose lacks an oxygen atom at the 2′ position compared to ribose.
10. The backbone of DNA is formed by:
A) Sugar-phosphate bonds
B) Hydrogen bonds between bases
C) Peptide bonds
D) Disulfide bonds
Answer A: Sugar-phosphate bonds
Rationale: Phosphodiester linkages connect the sugar of one nucleotide to the phosphate of the next.
11. A DNA molecule is:
A) Single-stranded
B) Double-stranded
C) Triple-stranded
D) Circular only
Answer B: Double-stranded
Rationale: DNA is typically a double helix.
, 12. The major and minor grooves of DNA are important for:
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A) DNA replication only
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B) Protein-DNA interactions
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C) RNA splicing
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D) Translation
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Answer B: Protein-DNA interactions
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Rationale: Grooves provide access for proteins that bind to specific DNA sequences.
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13. Histone proteins are important for:
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A) DNA replication
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B) DNA packaging into chromatin
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C) Transcription
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D) Translation
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Answer B: DNA packaging into chromatin
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Rationale: Histones help organize DNA into nucleosomes and higher-order structures.
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14. A nucleosome consists of:
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A) DNA wrapped around a histone octamer
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B) DNA wrapped around a single histone
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C) RNA wrapped around a histone octamer
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D) DNA and RNA together
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Answer A: DNA wrapped around a histone octamer
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Rationale: The nucleosome is the fundamental unit of chromatin.
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15. The histone octamer contains:
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A) Two copies each of H2A, H2B, H3, and H4
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B) One copy each of H1, H2A, H2B, H3, and H4
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C) Four copies of H1
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D) Eight different histones
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Answer A: Two copies each of H2A, H2B, H3, and H4
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Rationale: The core histone octamer consists of two of each of these four histones.
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Take & Pass the Exam
Questions 1–250
Section 1: DNA Structure and Organization (Questions 1–40)
1. The building blocks of DNA are:
A) Amino acids
B) Nucleotides
C) Monosaccharides
D) Fatty acids
Answer B: Nucleotides
Rationale: DNA is a polymer of nucleotides, each composed of a sugar, phosphate, and nitrogenous base.
2. A nucleotide in DNA consists of:
A) A phosphate group, a deoxyribose sugar, and a nitrogenous base
B) A phosphate group, a ribose sugar, and a nitrogenous base
C) A phosphate group, a deoxyribose sugar, and an amino acid
D) A sulfate group, a deoxyribose sugar, and a nitrogenous base
Answer A: A phosphate group, a deoxyribose sugar, and a nitrogenous base
Rationale: DNA nucleotides contain deoxyribose; RNA contains ribose.
3. Which of the following is NOT a nitrogenous base found in DNA?
A) Adenine
B) Guanine
C) Cytosine
D) Uracil
Answer D: Uracil
Rationale: Uracil is found in RNA; DNA contains thymine instead.
,4. The two strands of DNA are held together by:
A) Covalent bonds
B) Ionic bonds
C) Hydrogen bonds
D) Peptide bonds
Answer C: Hydrogen bonds
Rationale: Hydrogen bonds between complementary bases hold the two strands together.
5. In DNA, adenine pairs with:
A) Guanine
B) Cytosine
C) Thymine
D) Uracil
Answer C: Thymine
Rationale: A pairs with T via two hydrogen bonds.
6. In DNA, guanine pairs with:
A) Adenine
B) Cytosine
C) Thymine
D) Uracil
Answer B: Cytosine
Rationale: G pairs with C via three hydrogen bonds.
7. Chargaff's rules state that in DNA:
A) A = G and T = C
B) A = T and G = C
C) A = C and G = T
D) A + T = G + C
Answer B: A = T and G = C
Rationale: Complementary base pairing ensures A = T and G = C.
,8. The DNA double helix has:
A) Antiparallel strands
B) Parallel strands
C) Identical strands
D) Single-stranded regions
Answer A: Antiparallel strands
Rationale: The two strands run in opposite 5′→3′ directions.
9. The sugar in DNA is:
A) Ribose
B) Deoxyribose
C) Glucose
D) Fructose
Answer B: Deoxyribose
Rationale: Deoxyribose lacks an oxygen atom at the 2′ position compared to ribose.
10. The backbone of DNA is formed by:
A) Sugar-phosphate bonds
B) Hydrogen bonds between bases
C) Peptide bonds
D) Disulfide bonds
Answer A: Sugar-phosphate bonds
Rationale: Phosphodiester linkages connect the sugar of one nucleotide to the phosphate of the next.
11. A DNA molecule is:
A) Single-stranded
B) Double-stranded
C) Triple-stranded
D) Circular only
Answer B: Double-stranded
Rationale: DNA is typically a double helix.
, 12. The major and minor grooves of DNA are important for:
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A) DNA replication only
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B) Protein-DNA interactions
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C) RNA splicing
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D) Translation
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Answer B: Protein-DNA interactions
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Rationale: Grooves provide access for proteins that bind to specific DNA sequences.
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13. Histone proteins are important for:
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A) DNA replication
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B) DNA packaging into chromatin
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C) Transcription
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D) Translation
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Answer B: DNA packaging into chromatin
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Rationale: Histones help organize DNA into nucleosomes and higher-order structures.
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14. A nucleosome consists of:
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A) DNA wrapped around a histone octamer
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B) DNA wrapped around a single histone
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C) RNA wrapped around a histone octamer
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D) DNA and RNA together
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Answer A: DNA wrapped around a histone octamer
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Rationale: The nucleosome is the fundamental unit of chromatin.
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15. The histone octamer contains:
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A) Two copies each of H2A, H2B, H3, and H4
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B) One copy each of H1, H2A, H2B, H3, and H4
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C) Four copies of H1
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D) Eight different histones
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Answer A: Two copies each of H2A, H2B, H3, and H4
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Rationale: The core histone octamer consists of two of each of these four histones.
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