Chapter Exam

Chapter 2: Host Vector System — Online MCQ Test

Q: Which organism is most commonly used as a bacterial host in gene cloning experiments?

Answer: B. Escherichia coli — Escherichia coli is widely used because it grows rapidly, is easy to manipulate, and has well-studied genetics.

Q: Which of the following is NOT an essential feature of a typical cloning vector?

Answer: D. Mitochondrial membrane — A cloning vector requires an ori, selectable marker, and suitable restriction or cloning sites. A mitochondrial membrane is not a part of a cloning vector.

BIOTECHNOLOGY · Grade 12 · CBSE(NCERT)

Practice Chapter 2: Host Vector System with a free chapter-wise online MCQ test for CBSE(NCERT) Grade 12 BIOTECHNOLOGY. This chapter covers: Host Organism Vector Plasmid Bacteriophage Artificial Chromosome Escherichia coli Yeast Gene Transfer Cloning Vector Transformation Recombinant DNA. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 2: Host Vector System — Important Questions & Answers (FAQ)

Frequently asked questions from CBSE(NCERT) Grade 12 BIOTECHNOLOGY — Chapter 2: Host Vector System, with answers and explanations. These are sample questions; the exam has its own separate question set.

In recombinant DNA technology, what is a vector?

A. A DNA molecule used to carry a foreign DNA fragment into a host cell ✓
B. An enzyme that cuts DNA at specific sequences
C. A host cell that produces restriction enzymes
D. A protein that joins DNA fragments

Answer: A. A DNA molecule used to carry a foreign DNA fragment into a host cell
A vector acts as a carrier for introducing foreign DNA into a suitable host cell. Common examples include plasmids and bacteriophages.

Which organism is most commonly used as a bacterial host in gene cloning experiments?

A. Saccharomyces cerevisiae
B. Escherichia coli ✓
C. Agrobacterium tumefaciens
D. Neurospora crassa

Answer: B. Escherichia coli
Escherichia coli is widely used because it grows rapidly, is easy to manipulate, and has well-studied genetics.

Which of the following is NOT an essential feature of a typical cloning vector?

A. Origin of replication
B. Selectable marker
C. Cloning site
D. Mitochondrial membrane ✓

Answer: D. Mitochondrial membrane
A cloning vector requires an ori, selectable marker, and suitable restriction or cloning sites. A mitochondrial membrane is not a part of a cloning vector.

Which of the following best compares plasmid vectors and bacteriophage vectors?

A. Both always remain outside host cells and never replicate
B. Plasmids usually enter by transformation, while phage vectors enter through infection ✓
C. Plasmids infect bacteria like viruses, while phages need heat shock
D. Only plasmids can carry any foreign DNA; phages cannot

Answer: B. Plasmids usually enter by transformation, while phage vectors enter through infection
Plasmids are commonly introduced into competent cells by transformation. Bacteriophage vectors deliver DNA to bacterial cells through infection.

In a pBR322-like vector, a recombinant plasmid has an insert within the tetracycline resistance gene while the ampicillin resistance gene is intact. After replica plating, which colony type should be selected as recombinant?

A. Grows on ampicillin plate but fails to grow on tetracycline plate ✓
B. Fails to grow on both ampicillin and tetracycline plates
C. Grows on tetracycline plate but fails to grow on ampicillin plate
D. Grows equally well on both ampicillin and tetracycline plates

Answer: A. Grows on ampicillin plate but fails to grow on tetracycline plate
The intact ampR gene allows growth on ampicillin, but insertional inactivation of tetR prevents growth on tetracycline. This phenotype identifies recombinants.