BIOD 210 Genetics Module 7 Exam 2026/2027 UPDATE
UPDATED ACTUAL Questions and CORRECT Answers
1. Which enzyme is commonly referred to as ‘molecular scissors’ in genetic
engineering?
A. Restriction Endonuclease
B. DNA Ligase
C. DNA Polymerase
D. Reverse Transcriptase
Answer: A
Rationale: Restriction endonucleases cut DNA at specific recognition sequences, making
them the tools for cutting DNA in genetic engineering.
2. What is the primary function of the Polymerase Chain Reaction (PCR)?
A. To sequence a whole genome
B. To amplify a specific DNA segment
C. To cut DNA into fragments
D. To visualize proteins
Answer: B
Rationale: PCR is a technique used to make many copies (amplify) of a specific DNA region
in vitro.
3. In CRISPR-Cas9 technology, what is the role of the guide RNA (gRNA)?
A. To catalyze the DNA cleavage
B. To direct the Cas9 enzyme to the target DNA sequence
C. To provide a template for DNA repair
D. To join two DNA fragments together
Answer: B
,Rationale: The guide RNA is engineered to be complementary to the target DNA sequence,
guiding the Cas9 protein to the exact location for cutting.
4. Which step of PCR involves heating the reaction to approximately 95 degrees
Celsius?
A. Annealing
B. Extension
C. Ligation
D. Denaturation
Answer: D
Rationale: Denaturation occurs at high temperatures to break the hydrogen bonds
between DNA strands, separating them into single strands.
5. What is a plasmid in the context of biotechnology?
A. A small, circular extra-chromosomal DNA molecule used as a vector
B. A type of viral protein
C. The main chromosome of a eukaryotic cell
D. An enzyme that repairs DNA mutations
Answer: A
Rationale: Plasmids are small circular DNA molecules found in bacteria that are frequently
used as vectors to carry foreign DNA into host cells.
6. Which of the following is required for the synthesis of cDNA from mRNA?
A. Reverse Transcriptase
B. RNA Polymerase
C. Restriction enzymes
D. DNA Ligase
Answer: A
Rationale: Reverse transcriptase is an enzyme that synthesizes a complementary DNA
(cDNA) strand from an RNA template.
, 7. During gel electrophoresis, DNA fragments migrate toward the positive
electrode because:
A. DNA is negatively charged
B. DNA is positively charged
C. The gel is acidic
D. DNA is neutral but attracted to magnetism
Answer: A
Rationale: The phosphate groups in the DNA backbone give it a net negative charge,
causing it to move toward the positive anode.
8. What is the purpose of adding ddNTPs in Sanger sequencing?
A. To catalyze the formation of phosphodiester bonds
B. To act as primers for DNA synthesis
C. To label the DNA with radioactive isotopes
D. To terminate DNA chain elongation
Answer: D
Rationale: Dideoxynucleotides (ddNTPs) lack a 3’-OH group, which prevents the addition
of further nucleotides, resulting in chain termination.
9. Which organism is the source of the heat-stable DNA polymerase used in
PCR?
A. Thermus aquaticus
B. Saccharomyces cerevisiae
C. Escherichia coli
D. Drosophila melanogaster
Answer: A
Rationale: Taq polymerase is derived from the thermophilic bacterium Thermus
aquaticus, allowing it to remain functional at high PCR temperatures.
UPDATED ACTUAL Questions and CORRECT Answers
1. Which enzyme is commonly referred to as ‘molecular scissors’ in genetic
engineering?
A. Restriction Endonuclease
B. DNA Ligase
C. DNA Polymerase
D. Reverse Transcriptase
Answer: A
Rationale: Restriction endonucleases cut DNA at specific recognition sequences, making
them the tools for cutting DNA in genetic engineering.
2. What is the primary function of the Polymerase Chain Reaction (PCR)?
A. To sequence a whole genome
B. To amplify a specific DNA segment
C. To cut DNA into fragments
D. To visualize proteins
Answer: B
Rationale: PCR is a technique used to make many copies (amplify) of a specific DNA region
in vitro.
3. In CRISPR-Cas9 technology, what is the role of the guide RNA (gRNA)?
A. To catalyze the DNA cleavage
B. To direct the Cas9 enzyme to the target DNA sequence
C. To provide a template for DNA repair
D. To join two DNA fragments together
Answer: B
,Rationale: The guide RNA is engineered to be complementary to the target DNA sequence,
guiding the Cas9 protein to the exact location for cutting.
4. Which step of PCR involves heating the reaction to approximately 95 degrees
Celsius?
A. Annealing
B. Extension
C. Ligation
D. Denaturation
Answer: D
Rationale: Denaturation occurs at high temperatures to break the hydrogen bonds
between DNA strands, separating them into single strands.
5. What is a plasmid in the context of biotechnology?
A. A small, circular extra-chromosomal DNA molecule used as a vector
B. A type of viral protein
C. The main chromosome of a eukaryotic cell
D. An enzyme that repairs DNA mutations
Answer: A
Rationale: Plasmids are small circular DNA molecules found in bacteria that are frequently
used as vectors to carry foreign DNA into host cells.
6. Which of the following is required for the synthesis of cDNA from mRNA?
A. Reverse Transcriptase
B. RNA Polymerase
C. Restriction enzymes
D. DNA Ligase
Answer: A
Rationale: Reverse transcriptase is an enzyme that synthesizes a complementary DNA
(cDNA) strand from an RNA template.
, 7. During gel electrophoresis, DNA fragments migrate toward the positive
electrode because:
A. DNA is negatively charged
B. DNA is positively charged
C. The gel is acidic
D. DNA is neutral but attracted to magnetism
Answer: A
Rationale: The phosphate groups in the DNA backbone give it a net negative charge,
causing it to move toward the positive anode.
8. What is the purpose of adding ddNTPs in Sanger sequencing?
A. To catalyze the formation of phosphodiester bonds
B. To act as primers for DNA synthesis
C. To label the DNA with radioactive isotopes
D. To terminate DNA chain elongation
Answer: D
Rationale: Dideoxynucleotides (ddNTPs) lack a 3’-OH group, which prevents the addition
of further nucleotides, resulting in chain termination.
9. Which organism is the source of the heat-stable DNA polymerase used in
PCR?
A. Thermus aquaticus
B. Saccharomyces cerevisiae
C. Escherichia coli
D. Drosophila melanogaster
Answer: A
Rationale: Taq polymerase is derived from the thermophilic bacterium Thermus
aquaticus, allowing it to remain functional at high PCR temperatures.
