Question Bank — Biotechnology and its Applications

NCERT Class 12 Biology · Chapter 10 · CBSE Board Pattern

Class 12 Biology Chapter 10 Question Bank CBSE Board Pattern

QUESTION BANK

CBSE Class 12 Biology – Chapter 10: Biotechnology and its Applications
(Strictly based on NCERT text)

Section A — MCQs (1 mark each)

1. Which of the following is not an advantage of genetically modified crops as stated in the chapter?
(a) Increased tolerance to abiotic stresses
(b) Reduced post-harvest losses
(c) Increased dependence on chemical pesticides
(d) Enhanced nutritional value (e.g., Golden rice)

2. Bt toxin produced by Bacillus thuringiensis exists as inactive protoxin because:
(a) bacteria are resistant to the toxin
(b) toxin is immature
(c) toxin is inactive inside the bacterium
(d) bacteria enclose toxin in a special sac

3. The first clinical gene therapy was given in 1990 to a four-year-old girl suffering from:
(a) Cystic fibrosis
(b) Adenosine deaminase (ADA) deficiency
(c) Phenylketonuria
(d) Rheumatoid arthritis

4. Assertion (A): Meristem culture is used to obtain virus-free plants of banana, sugarcane and potato.
Reason (R): Meristem (apical and axillary) is free of virus even when the plant is infected.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

5. RNA interference (RNAi) technology was successfully used to protect tobacco plants from the nematode:
(a) Meloidogyne incognita
(b) Bacillus thuringiensis
(c) Agrobacterium tumefaciens
(d) Escherichia coli

6. Assertion (A): Human insulin produced by recombinant E. coli does not induce immunological responses in diabetic patients.
Reason (R): Recombinant human insulin is identical in structure to natural human insulin.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

7. The organisation set up by the Indian Government to make decisions regarding the validity of GM research and safety of GM organisms is:
(a) GEAC
(b) ELISA
(c) PCR
(d) RNAi

8. The process of producing thousands of genetically identical plants through tissue culture is called:
(a) Somatic hybridisation
(b) Micropropagation
(c) Totipotency
(d) Biopiracy

9. Transgenic cow “Rosie” produced human protein-enriched milk containing:
(a) α-1-antitrypsin
(b) Human alpha-lactalbumin
(c) ADA enzyme
(d) Cry protein

10. Which technique is routinely used for early detection of HIV in suspected AIDS patients?
(a) ELISA only
(b) PCR only
(c) Both PCR and ELISA
(d) Autoradiography

Section B — Very Short Answer (2 marks each)

11. Define totipotency. Name any two plants produced on commercial scale by micropropagation.
12. What are somaclones? How are they produced?
13. Why does Bt toxin not kill the bacterium that produces it?
14. Differentiate between sense and anti-sense RNA in the context of RNAi.
15. Name the two polypeptide chains of insulin and state how they are linked.
16. What is biopiracy? Give one example mentioned in the chapter.

Section C — Short Answer (3 marks each)

17. Explain the mechanism by which Bt toxin kills the target insect. Why is it considered a bio-pesticide?
18. Describe the role of Agrobacterium vectors in developing nematode-resistant tobacco plants using RNAi technology.
19. List any three benefits of genetically modified crops as stated in the chapter.
20. Differentiate between enzyme replacement therapy and gene therapy for ADA deficiency. Why is gene therapy considered a permanent cure only under specific conditions?
21. What is the principle of ELISA? How is it used in molecular diagnosis?

Section D — Long Answer (5 marks each)

22. Describe the production of human insulin using recombinant DNA technology. Why was it necessary to produce chains A and B separately? (Include a brief labelled description of the maturation of pro-insulin into insulin as shown in NCERT Figure 10.3.)

23. Explain the various applications of transgenic animals with suitable examples from the chapter. How do they help in (i) study of disease and (ii) production of biological products?

24. Discuss the ethical issues associated with biotechnology. Explain the role of GEAC and the problem of biopiracy with reference to Basmati rice and traditional herbal medicines.

Section E — Case/Source-Based (4 marks each)

Case 1

A farmer in a developing country is facing heavy losses due to cotton bollworm infestation. Scientists suggest the use of Bt cotton developed by introducing cry genes from Bacillus thuringiensis.

Sub-questions:

(a) Name the specific cry genes used to control cotton bollworms.
(b) Explain how the inactive protoxin becomes active inside the insect gut.
(c) State two advantages of using Bt cotton over chemical pesticides.
(d) Why is the choice of cry gene dependent on the crop and targeted pest?

Case 2

A four-year-old child is diagnosed with ADA deficiency. Lymphocytes are cultured outside the body, a functional ADA cDNA is introduced using a retroviral vector, and the modified cells are returned to the patient.

Sub-questions:

(a) What is gene therapy?
(b) Why are periodic infusions of genetically engineered lymphocytes required in this case?
(c) Under what condition can this therapy become a permanent cure?
(d) Name the vector used and one other disease for which transgenic models have been developed.

▶ Answer Key Attempt all questions first,
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Section A

  1. (c)
  2. (c)
  3. (b)
  4. (a)
  5. (a)
  6. (a)
  7. (a)
  8. (b)
  9. (b)
  10. (c)

Section B

  1. Totipotency — ability of any cell/explant to generate a whole plant (1). Tomato, banana, apple (1).
  2. Genetically identical plants produced by tissue culture/micropropagation (1+1).
  3. Toxin remains as inactive protoxin inside bacterium (2).
  4. Sense RNA — normal mRNA; anti-sense RNA — complementary strand that forms dsRNA (1+1).
  5. Chain A and Chain B linked by disulphide bridges (1+1).
  6. Use of bio-resources without proper authorisation/compensation (1); Basmati rice patent example (1).

Section C

  1. Alkaline pH solubilises crystals → active toxin binds midgut epithelium → pores → cell lysis & death (2); reduces chemical pesticide use (1).
  2. Agrobacterium introduces nematode-specific genes producing both sense & anti-sense RNA → dsRNA → RNAi → silencing of nematode mRNA (3).
  3. Any three: abiotic stress tolerance, reduced pesticide use, reduced post-harvest losses, better mineral use, enhanced nutrition (1 each).
  4. Enzyme replacement — temporary; gene therapy on lymphocytes — temporary; permanent only if introduced at early embryonic stage (3).
  5. Antigen-antibody interaction (1); detects pathogen antigens or antibodies (2).

Section D

  1. Two DNA sequences for A & B chains introduced separately in E. coli plasmids → chains extracted & joined by disulphide bonds (3); diagram description of pro-insulin → removal of C-peptide (2).
  2. Any five points covering physiology & development, disease models, biological products (Rosie), vaccine safety, chemical safety testing (5).
  3. Need for regulation, GEAC role, biopiracy definition + Basmati & turmeric/neem examples (5).

Section E

Case 1: (a) cryIAc, cryIIAb (1); (b) Alkaline gut pH activates toxin (1); (c) Any two advantages (1+1); (d) Insect-group specificity (1).
Case 2: (a) Correction of gene defect by inserting functional gene (1); (b) Lymphocytes are not immortal (1); (c) Introduction at early embryonic stage (1); (d) Retroviral vector; any one disease model (cancer, cystic fibrosis, etc.) (1).

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All questions are answerable from the NCERT chapter text. Reviewed by GFIS faculty.