Chapter Exam

Chapter 9: Biotechnology Principles and Processes — Online MCQ Test

Q: Which enzyme is used to join two DNA fragments by forming phosphodiester bonds?

Answer: B. DNA ligase — DNA ligase joins DNA fragments by sealing nicks and forming phosphodiester bonds between adjacent nucleotides.

Q: Restriction enzymes are also known as:

Answer: A. Molecular scissors — Restriction enzymes cut DNA at specific recognition sequences, so they are commonly called molecular scissors.

Q: In recombinant DNA technology, a cloning vector is mainly used to:

Answer: B. Carry foreign DNA into a host cell — A cloning vector is a DNA molecule that carries foreign DNA into a host cell and helps in its replication.

Q: Which bacterium is commonly used as a host in recombinant DNA experiments?

Answer: B. Escherichia coli — Escherichia coli is widely used as a host because it is easy to grow and genetically manipulate.

Q: Which of the following is NOT an essential feature of a cloning vector according to NCERT?

Answer: D. Centromere for mitosis in bacteria — Bacterial cloning vectors require ori, selectable marker and cloning sites; bacteria do not use centromeres for mitosis.

Q: During isolation of DNA from a fungal cell, which enzyme is used to break down the cell wall?

Answer: C. Chitinase — Fungal cell walls contain chitin, so chitinase is used to digest them during DNA isolation.

Q: In the naming of EcoRI, what does the letter R represent?

Answer: A. The strain of Escherichia coli — In EcoRI, E represents Escherichia, co represents coli, R represents the strain, and I indicates it was the first enzyme isolated from that strain.

Q: A circular plasmid has two recognition sites for a restriction enzyme. If this enzyme is used alone, what will happen to the plasmid?

Answer: B. It will be cut into two linear DNA fragments — A circular DNA molecule cut at two sites by the same restriction enzyme forms two linear fragments.

BIOLOGY · Grade 12 · CBSE(NCERT)

Practice Chapter 9: Biotechnology Principles and Processes with a free chapter-wise online MCQ test for CBSE(NCERT) Grade 12 BIOLOGY. This chapter covers: Biotechnology Recombinant DNA Restriction Enzymes DNA Ligase Cloning Vector Gene Cloning PCR Bioreactor Genetic Engineering Transformation. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 9: Biotechnology Principles and Processes — Important Questions & Answers (FAQ)

Frequently asked questions from CBSE(NCERT) Grade 12 BIOLOGY — Chapter 9: Biotechnology Principles and Processes, with answers and explanations. These are sample questions; the exam has its own separate question set.

Which enzyme is used to join two DNA fragments by forming phosphodiester bonds?

A. DNA polymerase
B. DNA ligase ✓
C. Restriction endonuclease
D. RNA polymerase

Answer: B. DNA ligase
DNA ligase joins DNA fragments by sealing nicks and forming phosphodiester bonds between adjacent nucleotides.

Restriction enzymes are also known as:

A. Molecular scissors ✓
B. Molecular glue
C. Cloning vehicles
D. Thermal cyclers

Answer: A. Molecular scissors
Restriction enzymes cut DNA at specific recognition sequences, so they are commonly called molecular scissors.

In recombinant DNA technology, a cloning vector is mainly used to:

A. Destroy foreign DNA
B. Carry foreign DNA into a host cell ✓
C. Stain DNA fragments
D. Digest proteins

Answer: B. Carry foreign DNA into a host cell
A cloning vector is a DNA molecule that carries foreign DNA into a host cell and helps in its replication.

Which bacterium is commonly used as a host in recombinant DNA experiments?

A. Rhizobium
B. Escherichia coli ✓
C. Lactobacillus
D. Mycobacterium

Answer: B. Escherichia coli
Escherichia coli is widely used as a host because it is easy to grow and genetically manipulate.

Which of the following is NOT an essential feature of a cloning vector according to NCERT?

A. Origin of replication
B. Selectable marker
C. Cloning site
D. Centromere for mitosis in bacteria ✓

Answer: D. Centromere for mitosis in bacteria
Bacterial cloning vectors require ori, selectable marker and cloning sites; bacteria do not use centromeres for mitosis.

During isolation of DNA from a fungal cell, which enzyme is used to break down the cell wall?

A. Lysozyme
B. Cellulase
C. Chitinase ✓
D. Lipase

Answer: C. Chitinase
Fungal cell walls contain chitin, so chitinase is used to digest them during DNA isolation.

EcoRI recognizes the sequence 5'-GAATTC-3'. After cutting, it produces sticky ends because:

A. It cuts both strands exactly at the centre, producing blunt ends
B. It cuts the two DNA strands at different positions, producing overhangs ✓
C. It removes all adenine bases from DNA
D. It converts double-stranded DNA into RNA

Answer: B. It cuts the two DNA strands at different positions, producing overhangs
EcoRI cuts asymmetrically between G and A on opposite strands, producing single-stranded overhangs called sticky ends.

A plasmid has two antibiotic resistance genes, ampR and tetR. A foreign DNA insert disrupts ampR. Which plate pattern identifies recombinants?

A. Growth on ampicillin and no growth on tetracycline
B. No growth on ampicillin but growth on tetracycline ✓
C. Growth on both ampicillin and tetracycline
D. No growth on both ampicillin and tetracycline

Answer: B. No growth on ampicillin but growth on tetracycline
Disruption of ampR makes recombinants sensitive to ampicillin, while tetR remains intact and gives tetracycline resistance.

In the naming of EcoRI, what does the letter R represent?

A. The strain of Escherichia coli ✓
B. The genus of the source organism
C. The species of the source organism
D. The order in which the enzyme was isolated

Answer: A. The strain of Escherichia coli
In EcoRI, E represents Escherichia, co represents coli, R represents the strain, and I indicates it was the first enzyme isolated from that strain.

A circular plasmid has two recognition sites for a restriction enzyme. If this enzyme is used alone, what will happen to the plasmid?

A. It will remain circular with one nick
B. It will be cut into two linear DNA fragments ✓
C. It will produce only one linear DNA fragment
D. It will be amplified exponentially

Answer: B. It will be cut into two linear DNA fragments
A circular DNA molecule cut at two sites by the same restriction enzyme forms two linear fragments.

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