Biotechnology and its Applications — Class 12 MCQs with Answers

Biotechnology and its Applications — important questions & MCQs with answers (Class 12 Biology)

14 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 76 are timed and scored when you sign in.

1. Q1Easy

   Bt cotton resists:

   A.Cold

   B.Drought

   C.Bollworm pests✓ Correct

   D.Salinity only

   Answer: C. Bollworm pests

   Explanation: Bt cotton carries a cry gene from Bacillus thuringiensis, letting the plant make its own Cry protein toxic to bollworm larvae — it's pest resistance, not tolerance to cold, drought or salinity.

2. Q2Easy

   Recombinant insulin (Humulin) is produced in:

   A.Plants only

   B.Cattle pancreas

   C.Pig liver

   D.E. coli (bacteria)✓ Correct

   Answer: D. E. coli (bacteria)

   Explanation: Humulin is made by inserting the human insulin gene into E. coli, which then synthesises the A and B chains — not extracted from pig or cattle pancreas, avoiding animal-insulin allergies.

3. Q3Easy

   An organism whose genes have been altered by genetic engineering is called a:

   A.Hybrid only

   B.Genetically modified organism (GMO)✓ Correct

   C.Clone

   D.Mutant only

   Answer: B. Genetically modified organism (GMO)

   Explanation: A GMO (transgenic organism) has had its genome deliberately altered by inserting foreign DNA via genetic engineering — distinct from a hybrid (cross-breeding) or a mutant (random mutation).

4. Q4Easy

   Human insulin produced by recombinant DNA technology is called:

   A.Humulin✓ Correct

   B.Interferon

   C.Streptokinase

   D.Statin

   Answer: A. Humulin

   Explanation: Humulin is the trade name for recombinant human insulin made in E. coli — distinct from interferon (antiviral protein) or streptokinase (clot-dissolving enzyme), also biotech products but for other uses.

5. Q5Easy

   Bt cotton is resistant to certain insect pests because it carries a gene from:

   A.Bacillus thuringiensis✓ Correct

   B.Agrobacterium

   C.E. coli

   D.Yeast

   Answer: A. Bacillus thuringiensis

   Explanation: Bt cotton's insect resistance comes from a cry gene taken from the soil bacterium Bacillus thuringiensis, not from Agrobacterium, which is only used as the gene-delivery vector, or from E. coli.

6. Q6Easy

   Mature insulin consists of two polypeptide chains linked by:

   A.Peptide bonds between them

   B.Hydrogen bonds only

   C.Disulphide bonds✓ Correct

   D.Ionic bonds only

   Answer: C. Disulphide bonds

   Explanation: Mature insulin's A and B chains are held together by disulphide bonds formed after the connecting C-peptide is enzymatically removed from proinsulin — not simple peptide or hydrogen bonds.

7. Q7Medium

   The Bt protoxin becomes an active toxin in the insect gut because the gut is:

   A.Acidic

   B.Alkaline, which solubilises the crystal protoxin✓ Correct

   C.Neutral and dry

   D.Cold

   Answer: B. Alkaline, which solubilises the crystal protoxin

   Explanation: The Bt protoxin crystal is insoluble at the near-neutral pH of most environments but dissolves in the insect midgut's alkaline conditions, releasing the toxin only once ingested — not in acidic or dry conditions.

8. Q8Medium

   Gene therapy aims to:

   A.Treat genetic disorders by inserting/modifying genes✓ Correct

   B.Build muscles

   C.Lose weight

   D.Cool body

   Answer: A. Treat genetic disorders by inserting/modifying genes

   Explanation: Gene therapy corrects a genetic disorder by inserting a functional gene, or modifying a faulty one, into a patient's cells — the first success, in 1990, treated ADA deficiency (SCID), not muscle-building.

9. Q9Medium

   Activated Bt toxin kills insects by:

   A.Producing antibodies

   B.Blocking respiration in plants

   C.Cutting insect DNA

   D.Creating pores in the midgut epithelial cells, causing them to swell and lyse✓ Correct

   Answer: D. Creating pores in the midgut epithelial cells, causing them to swell and lyse

   Explanation: Once activated, Bt toxin binds midgut epithelial cell receptors and inserts pores into the membrane, causing the cells to swell, lyse and kill the insect — it has no effect on plant respiration or DNA.

10. Q10Medium

    PCR is used in diagnostics for:

    A.Sterilisation

    B.Surgery

    C.Detecting pathogen DNA quickly✓ Correct

    D.Anaesthesia

    Answer: C. Detecting pathogen DNA quickly

    Explanation: PCR amplifies even trace amounts of a pathogen's DNA or RNA millions-fold, so infections like HIV, tuberculosis or COVID can be detected within days of exposure — far earlier than antibody-based tests.

11. Q11Medium

    RNAi silences a gene by using:

    A.Antibodies

    B.A restriction enzyme

    C.A plasmid only

    D.Double-stranded RNA complementary to the target mRNA✓ Correct

    Answer: D. Double-stranded RNA complementary to the target mRNA

    Explanation: RNAi works by introducing double-stranded RNA whose sequence is complementary to a target mRNA; this pairing triggers the cell's machinery to degrade that specific mRNA, silencing the gene.

12. Q12Hard

    Golden rice is engineered to produce:

    A.Iron only

    B.β-carotene (Vitamin A precursor)✓ Correct

    C.Protein only

    D.Sugar

    Answer: B. β-carotene (Vitamin A precursor)

    Explanation: Golden rice carries phytoene synthase and other carotenoid-pathway genes (from daffodil/maize plus a bacterium) so its endosperm accumulates β-carotene, the Vitamin A precursor — not iron or protein.

13. Q13Hard

    Monoclonal antibodies are:

    A.Lipids

    B.Random mixture

    C.Identical antibodies from a single B-cell clone✓ Correct

    D.Carbohydrates

    Answer: C. Identical antibodies from a single B-cell clone

    Explanation: Monoclonal antibodies come from a single B-cell clone fused with a myeloma cell via hybridoma technology, so every molecule is identical and binds one epitope — unlike the mixed antibodies in normal serum.

14. Q14Hard

    Assertion: Bt toxin does not kill the Bacillus that produces it. Reason: The toxin exists as an inactive protoxin and is activated only in the alkaline insect gut. Choose the correct option.

    A.Both false

    B.Both true, reason does not explain

    C.Assertion true, reason false

    D.Both true and reason explains assertion✓ Correct

    Answer: D. Both true and reason explains assertion

    Explanation: Both statements are true, and the reason explains the assertion: because the toxin is stored as an inactive protoxin that activates only in the insect's alkaline gut, it never harms the producing bacterium.

Biotechnology and its Applications — FAQs

More Class 12 Biology chapters

• 01Sexual Reproduction in Flowering Plants
• 02Human Reproduction
• 03Reproductive Health
• 04Principles of Inheritance and Variation
• 05Molecular Basis of Inheritance
• 06Evolution

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• Class 12 Chemistry chapters
• Class 12 Computer Science chapters
• Class 12 English chapters
• Class 12 Mathematics chapters
• Class 12 Physics chapters