BIOL 210 Module 9: Genetics and Biotechnology
Updated and Latest Questions and Correct
Answers with Rationale
1. Which enzyme is responsible for ‘cutting’ DNA at specific palindromic sequences in genetic
engineering?
A. Restriction Endonuclease
B. DNA Ligase
C. DNA Polymerase
D. RNA Primase
Correct Answer: A
Explanation: Restriction endonucleases, or restriction enzymes, act as ‘molecular scissors’
that cut DNA at specific recognition sites, which are usually palindromic sequences.
2. In the process of creating recombinant DNA, which enzyme ‘pastes’ the DNA fragments
together by forming phosphodiester bonds?
A. DNA Helicase
B. DNA Ligase
C. Reverse Transcriptase
D. Topoisomerase
Correct Answer: B
Explanation: DNA ligase is used to join DNA fragments together by catalyzing the
formation of covalent phosphodiester bonds between the phosphate group of one strand
and the deoxyribose of another.
3. What is the primary purpose of the Polymerase Chain Reaction (PCR)?
A. To amplify a specific DNA segment into millions of copies
B. To sequence the entire genome in one step
C. To insert foreign DNA into a bacterial plasmid
D. To separate DNA fragments based on their size and charge
Correct Answer: A
Explanation: PCR is a laboratory technique used to make numerous copies of a specific
DNA segment, making it easier to analyze small samples of genetic material.
, 4. During the denaturation step of PCR, what happens to the DNA?
A. Primers bind to the target DNA sequence
B. DNA polymerase adds nucleotides to the 3’ end
C. The hydrogen bonds between the two strands are broken by heat
D. The DNA is cut into smaller fragments by enzymes
Correct Answer: C
Explanation: Denaturation involves heating the DNA to around 94-98 degrees Celsius,
which breaks the hydrogen bonds between complementary base pairs, resulting in two
single strands.
5. Which of the following is a characteristic of Taq polymerase that makes it ideal for PCR?
A. It is highly resistant to heat denaturation
B. It works best at room temperature
C. It can proofread and correct all errors
D. It synthesizes DNA in the 3’ to 5’ direction
Correct Answer: A
Explanation: Taq polymerase is derived from the thermophilic bacterium Thermus
aquaticus, allowing it to remain stable and functional through multiple high-heat
denaturation cycles.
6. In gel electrophoresis, DNA fragments move toward the positive electrode (anode) because
DNA:
A. Is positively charged due to nitrogenous bases
B. Is neutral and moves by diffusion
C. Is attracted to the agarose gel matrix
D. Is negatively charged due to the phosphate backbone
Correct Answer: D
Explanation: The phosphate groups in the DNA backbone carry a negative charge, causing
the molecules to migrate toward the positive pole in an electric field.
7. A researcher wants to insert a human gene into a bacterial plasmid. What must be true
about the restriction enzymes used?
A. Two different enzymes must be used for the gene and the plasmid
B. The same restriction enzyme should be used to create compatible ‘sticky ends’
Updated and Latest Questions and Correct
Answers with Rationale
1. Which enzyme is responsible for ‘cutting’ DNA at specific palindromic sequences in genetic
engineering?
A. Restriction Endonuclease
B. DNA Ligase
C. DNA Polymerase
D. RNA Primase
Correct Answer: A
Explanation: Restriction endonucleases, or restriction enzymes, act as ‘molecular scissors’
that cut DNA at specific recognition sites, which are usually palindromic sequences.
2. In the process of creating recombinant DNA, which enzyme ‘pastes’ the DNA fragments
together by forming phosphodiester bonds?
A. DNA Helicase
B. DNA Ligase
C. Reverse Transcriptase
D. Topoisomerase
Correct Answer: B
Explanation: DNA ligase is used to join DNA fragments together by catalyzing the
formation of covalent phosphodiester bonds between the phosphate group of one strand
and the deoxyribose of another.
3. What is the primary purpose of the Polymerase Chain Reaction (PCR)?
A. To amplify a specific DNA segment into millions of copies
B. To sequence the entire genome in one step
C. To insert foreign DNA into a bacterial plasmid
D. To separate DNA fragments based on their size and charge
Correct Answer: A
Explanation: PCR is a laboratory technique used to make numerous copies of a specific
DNA segment, making it easier to analyze small samples of genetic material.
, 4. During the denaturation step of PCR, what happens to the DNA?
A. Primers bind to the target DNA sequence
B. DNA polymerase adds nucleotides to the 3’ end
C. The hydrogen bonds between the two strands are broken by heat
D. The DNA is cut into smaller fragments by enzymes
Correct Answer: C
Explanation: Denaturation involves heating the DNA to around 94-98 degrees Celsius,
which breaks the hydrogen bonds between complementary base pairs, resulting in two
single strands.
5. Which of the following is a characteristic of Taq polymerase that makes it ideal for PCR?
A. It is highly resistant to heat denaturation
B. It works best at room temperature
C. It can proofread and correct all errors
D. It synthesizes DNA in the 3’ to 5’ direction
Correct Answer: A
Explanation: Taq polymerase is derived from the thermophilic bacterium Thermus
aquaticus, allowing it to remain stable and functional through multiple high-heat
denaturation cycles.
6. In gel electrophoresis, DNA fragments move toward the positive electrode (anode) because
DNA:
A. Is positively charged due to nitrogenous bases
B. Is neutral and moves by diffusion
C. Is attracted to the agarose gel matrix
D. Is negatively charged due to the phosphate backbone
Correct Answer: D
Explanation: The phosphate groups in the DNA backbone carry a negative charge, causing
the molecules to migrate toward the positive pole in an electric field.
7. A researcher wants to insert a human gene into a bacterial plasmid. What must be true
about the restriction enzymes used?
A. Two different enzymes must be used for the gene and the plasmid
B. The same restriction enzyme should be used to create compatible ‘sticky ends’
