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BIOD 210 Module 1-7 Exam Genetics
Questions and Answers (Verified Answers)
2026/ 2027, 100% Guaranteed Pass
||Complete A+ Guide
1. Which of the following chemical groups is found at the 5′
end of a DNA strand?
a) Hydroxyl group
b) Phosphate group
c) Methyl group
d) Carboxyl group
Answer: b) Phosphate group
Rationale: The 5′ carbon of the deoxyribose sugar bears a
free phosphate group; the 3′ carbon bears a free hydroxyl
group.
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2. A double-stranded DNA molecule contains 20% adenine.
What percentage of guanine does it contain?
a) 20%
b) 30%
c) 40%
d) 60%
Answer: b) 30%
Rationale: A=T, so T=20%; A+T=40%; therefore G+C=60%;
G=C, so G=30%.
3. Which enzyme catalyzes the formation of a phosphodiester
bond during DNA replication?
a) Helicase
b) Primase
c) DNA polymerase
d) Topoisomerase
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Answer: c) DNA polymerase
Rationale: DNA polymerase adds nucleotides to the 3′-OH
group, forming phosphodiester bonds.
4. In the Meselson-Stahl experiment, after two rounds of
replication in 14N medium, what proportion of DNA molecules
are hybrid (15N/14N)?
a) 0%
b) 25%
c) 50%
d) 100%
Answer: c) 50%
Rationale: After 1 round: all hybrid. After 2 rounds: 50%
hybrid, 50% light.
5. Which of the following is not a component of a nucleotide?
a) Nitrogenous base
b) Pentose sugar
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c) Phosphate group m.
d) Amino acid m.
Answer: d) Amino acid m. m. m.
Rationale: Nucleotides consist of base + sugar + phosphate;
m. m. m. m. m. m. m. m.
m. amino acids are protein monomers.
m. m. m. m.
6. The lagging strand is synthesized discontinuously as:
m. m. m. m. m. m.
a) Okazaki fragments m.
b) Leading strand fragments m. m.
c) RNA primers only
m. m.
d) Telomeres
Answer: a) Okazaki fragments
m. m. m.
Rationale: The lagging strand is synthesized 5′→3′ away from
m. m. m. m. m. m. m. m.
m. the replication fork in short segments.
m. m. m. m. m.
7. Which enzyme unwinds the DNA double helix?
m . m . m . m . m. m .
a) DNA polymerase III
m. m.
b) Topoisomerase
BIOD 210 Module 1-7 Exam Genetics
Questions and Answers (Verified Answers)
2026/ 2027, 100% Guaranteed Pass
||Complete A+ Guide
1. Which of the following chemical groups is found at the 5′
end of a DNA strand?
a) Hydroxyl group
b) Phosphate group
c) Methyl group
d) Carboxyl group
Answer: b) Phosphate group
Rationale: The 5′ carbon of the deoxyribose sugar bears a
free phosphate group; the 3′ carbon bears a free hydroxyl
group.
,Page 2 of 163
2. A double-stranded DNA molecule contains 20% adenine.
What percentage of guanine does it contain?
a) 20%
b) 30%
c) 40%
d) 60%
Answer: b) 30%
Rationale: A=T, so T=20%; A+T=40%; therefore G+C=60%;
G=C, so G=30%.
3. Which enzyme catalyzes the formation of a phosphodiester
bond during DNA replication?
a) Helicase
b) Primase
c) DNA polymerase
d) Topoisomerase
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Answer: c) DNA polymerase
Rationale: DNA polymerase adds nucleotides to the 3′-OH
group, forming phosphodiester bonds.
4. In the Meselson-Stahl experiment, after two rounds of
replication in 14N medium, what proportion of DNA molecules
are hybrid (15N/14N)?
a) 0%
b) 25%
c) 50%
d) 100%
Answer: c) 50%
Rationale: After 1 round: all hybrid. After 2 rounds: 50%
hybrid, 50% light.
5. Which of the following is not a component of a nucleotide?
a) Nitrogenous base
b) Pentose sugar
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c) Phosphate group m.
d) Amino acid m.
Answer: d) Amino acid m. m. m.
Rationale: Nucleotides consist of base + sugar + phosphate;
m. m. m. m. m. m. m. m.
m. amino acids are protein monomers.
m. m. m. m.
6. The lagging strand is synthesized discontinuously as:
m. m. m. m. m. m.
a) Okazaki fragments m.
b) Leading strand fragments m. m.
c) RNA primers only
m. m.
d) Telomeres
Answer: a) Okazaki fragments
m. m. m.
Rationale: The lagging strand is synthesized 5′→3′ away from
m. m. m. m. m. m. m. m.
m. the replication fork in short segments.
m. m. m. m. m.
7. Which enzyme unwinds the DNA double helix?
m . m . m . m . m. m .
a) DNA polymerase III
m. m.
b) Topoisomerase
