Chapter Exam

Chapter 10: Biotechnology and its Applications — Online MCQ Test

Q: The bacterium used as the source of Bt toxin genes in genetically modified crops is:

Answer: A. Bacillus thuringiensis — Bt toxin genes are isolated from Bacillus thuringiensis. These genes are used to produce insect-resistant crops such as Bt cotton.

Q: Which cry genes are commonly associated with control of cotton bollworms in Bt cotton?

Answer: A. cryIAc and cryIIAb — NCERT mentions cryIAc and cryIIAb as genes that control cotton bollworms. cryIAb is associated with control of corn borer.

Q: In the production of human insulin by recombinant DNA technology, Eli Lilly prepared two DNA sequences corresponding to:

Answer: A. A and B chains of insulin — Eli Lilly prepared DNA sequences for the A and B chains of human insulin and expressed them separately in E. coli. The chains were later joined by disulphide bonds.

Q: ADA deficiency is caused by the lack of which enzyme?

Answer: A. Adenosine deaminase — ADA deficiency occurs due to the deficiency of adenosine deaminase. This enzyme is important for immune system functioning.

Q: Bt toxin does not harm Bacillus thuringiensis itself because the toxin is present in the bacterium as:

Answer: A. An inactive protoxin — Bt toxin is produced as an inactive protoxin in Bacillus thuringiensis. It becomes active only under suitable conditions in the insect gut.

Q: The Bt protoxin becomes active in the insect gut mainly because of:

Answer: A. Alkaline pH of the gut — The alkaline pH of the insect gut solubilises the crystals and converts the protoxin into active toxin. The active toxin damages the insect midgut cells.

Q: Which of the following pairs is incorrectly matched?

Answer: A. cryIAb - Cotton bollworm — cryIAb is associated with control of corn borer, not cotton bollworm. Cotton bollworms are controlled by cryIAc and cryIIAb.

BIOLOGY · Grade 12 · CBSE(NCERT)

Practice Chapter 10: Biotechnology and its Applications with a free chapter-wise online MCQ test for CBSE(NCERT) Grade 12 BIOLOGY. This chapter covers: Bt Cotton Human Insulin Gene Therapy PCR ELISA Molecular Diagnosis Transgenic Animals Biopiracy Genetic Engineering Agriculture Medicine Biotechnology. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 10: Biotechnology and its Applications — Important Questions & Answers (FAQ)

Frequently asked questions from CBSE(NCERT) Grade 12 BIOLOGY — Chapter 10: Biotechnology and its Applications, with answers and explanations. These are sample questions; the exam has its own separate question set.

The bacterium used as the source of Bt toxin genes in genetically modified crops is:

A. Bacillus thuringiensis ✓
B. Agrobacterium tumefaciens
C. Escherichia coli
D. Rhizobium leguminosarum

Answer: A. Bacillus thuringiensis
Bt toxin genes are isolated from Bacillus thuringiensis. These genes are used to produce insect-resistant crops such as Bt cotton.

Which cry genes are commonly associated with control of cotton bollworms in Bt cotton?

A. cryIAc and cryIIAb ✓
B. cryIAb and cryIIIAb
C. cryIIIAb and cryIV
D. cryIIAb and cryIV

Answer: A. cryIAc and cryIIAb
NCERT mentions cryIAc and cryIIAb as genes that control cotton bollworms. cryIAb is associated with control of corn borer.

In the production of human insulin by recombinant DNA technology, Eli Lilly prepared two DNA sequences corresponding to:

A. A and B chains of insulin ✓
B. C and D chains of insulin
C. Alpha and beta globin chains
D. Heavy and light antibody chains

Answer: A. A and B chains of insulin
Eli Lilly prepared DNA sequences for the A and B chains of human insulin and expressed them separately in E. coli. The chains were later joined by disulphide bonds.

ADA deficiency is caused by the lack of which enzyme?

A. Adenosine deaminase ✓
B. DNA polymerase
C. Reverse transcriptase
D. Restriction endonuclease

Answer: A. Adenosine deaminase
ADA deficiency occurs due to the deficiency of adenosine deaminase. This enzyme is important for immune system functioning.

Bt toxin does not harm Bacillus thuringiensis itself because the toxin is present in the bacterium as:

A. An inactive protoxin ✓
B. A fully active enzyme
C. A harmless carbohydrate
D. A viral protein

Answer: A. An inactive protoxin
Bt toxin is produced as an inactive protoxin in Bacillus thuringiensis. It becomes active only under suitable conditions in the insect gut.

The Bt protoxin becomes active in the insect gut mainly because of:

A. Alkaline pH of the gut ✓
B. Acidic pH of the stomach
C. Absence of digestive enzymes
D. Low temperature inside the insect

Answer: A. Alkaline pH of the gut
The alkaline pH of the insect gut solubilises the crystals and converts the protoxin into active toxin. The active toxin damages the insect midgut cells.

In Bt crops, the active toxin kills insects mainly by:

A. Binding to receptors on midgut epithelial cells and creating pores ✓
B. Blocking photosynthesis in leaves
C. Destroying plant xylem vessels
D. Inhibiting seed germination

Answer: A. Binding to receptors on midgut epithelial cells and creating pores
The activated Bt toxin binds to specific receptors on the epithelial cells of the insect midgut. This creates pores, causing swelling, lysis and death of the insect.

Which of the following pairs is incorrectly matched?

A. cryIAb - Cotton bollworm ✓
B. cryIAc - Cotton bollworm
C. cryIIAb - Cotton bollworm
D. cryIAb - Corn borer

Answer: A. cryIAb - Cotton bollworm
cryIAb is associated with control of corn borer, not cotton bollworm. Cotton bollworms are controlled by cryIAc and cryIIAb.

A scientist introduces a cry gene into a crop, but a particular insect species still survives after feeding on it. The most NCERT-based explanation is:

A. Bt toxins are insect-group specific and require specific gut receptors ✓
B. All cry genes kill all insects equally
C. Bt toxin is activated only in human stomach
D. cry genes work only in bacteria and never in plants

Answer: A. Bt toxins are insect-group specific and require specific gut receptors
Different cry genes produce toxins specific to particular insect groups. The toxin must bind to specific receptors in the insect midgut to be effective.

For ADA deficiency, which approach is most likely to provide a permanent cure according to NCERT?

A. Introducing the functional ADA gene into cells at an early embryonic stage ✓
B. Repeatedly injecting mature modified lymphocytes only
C. Giving insulin produced by E. coli
D. Spraying Bt toxin on bone marrow cells

Answer: A. Introducing the functional ADA gene into cells at an early embryonic stage
NCERT states that permanent cure can be achieved if the gene isolated from marrow cells producing ADA is introduced into cells at early embryonic stages. Mature lymphocyte therapy is not permanent.

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