Exercise Solutions Available
Step-by-step answers for all textbook questions in this chapter
Chapter 19 — Biotechnology and its Applications Exercise Solutions
Applications of biotechnology in medicine and agriculture are key exam topics. Know specific examples with scientific details.
How to Use This Page
1. Start with the Key Concepts table to refresh definitions quickly. 2. Attempt the MCQs, fill-in-the-blanks, and true-or-false on your own before checking answers. 3. Use the brief and detailed answer sections to practise writing model responses. 4. Review the Common Mistakes and Exam Checklist before your exam.
Key Concepts (Quick Recap)
| Term | Definition |
|---|---|
| Biotechnology | Use of living organisms or their enzymes to produce products/services for human use |
| Recombinant DNA (rDNA) | DNA formed by combining genes from two different organisms using restriction enzymes and ligase |
| Plasmid | Small circular extra-chromosomal DNA in bacteria, used as a vector in gene cloning |
| Restriction enzyme | Endonuclease that cuts DNA at specific palindromic sequences; produces sticky or blunt ends |
| GMO | Genetically Modified Organism — organism with altered genetic material via genetic engineering |
| Transgenic organism | GMO that carries a gene from a different species (foreign gene = transgene) |
| cry gene | Gene from Bacillus thuringiensis encoding Cry protein (delta-endotoxin), toxic to insect larvae |
| Gene therapy | Correction of a genetic defect by inserting a functional gene into patient cells |
| Golden Rice | Transgenic rice enriched with beta-carotene (pro-vitamin A) using psy and crtI genes |
| Humulin | Recombinant human insulin produced in E. coli (Eli Lilly, 1982) |
| SCNT | Somatic Cell Nuclear Transfer — technique used to clone Dolly the sheep |
| GEAC | Genetic Engineering Appraisal Committee — India's regulatory body for GMO approval |
| Biopiracy | Unauthorized commercial use of traditional knowledge or biological resources |
| PCR | Polymerase Chain Reaction — amplifies DNA segments in vitro using Taq polymerase |
| ELISA | Enzyme-Linked Immunosorbent Assay — diagnostic test detecting antigens or antibodies |
Applications in Medicine
| Application | Organism Used | Product | Use |
|---|---|---|---|
| Insulin production | E. coli | Humulin | Diabetes treatment |
| Growth hormone | E. coli | Somatotropin | Growth disorders |
| Hepatitis B vaccine | Yeast (S. cerevisiae) | HBsAg | Hepatitis B prevention |
| Interferon | E. coli | Alpha-interferon | Antiviral, cancer |
| tPA | CHO cells | Tissue plasminogen activator | Blood clot dissolution |
| Erythropoietin | CHO cells | EPO | Anaemia treatment |
Bt Crops — Details
| Crop | Gene | Pest Target |
|---|---|---|
| Bt cotton | cry1Ac | American bollworm (Helicoverpa armigera) |
| Bt brinjal | cry1Ab/cry1Ac | Fruit and shoot borer (Leucinodes orbonalis) |
| Bt maize | cry1Ab | European corn borer |
Mechanism: Alkaline gut of insect activates Cry protein → binds to midgut receptors → membrane pores form → cell lysis → insect dies.
Benefits: Reduced pesticide use, higher yield, lower cost. Concerns: Non-target organism effects, gene flow to wild relatives, superweeds, biodiversity.
Transgenic Animals
| Animal | Modification | Purpose |
|---|---|---|
| Rosie cow | Human alpha-lactalbumin gene | Protein-enriched milk |
| Dolly sheep | Somatic cell nuclear transfer (SCNT) | First cloned mammal (1997) |
| Knockout mice | Target gene inactivated | Disease model research |
| GloFish | GFP (jellyfish) gene | Aquarium fish |
| Alpha-1-antitrypsin sheep | Human gene | Treat emphysema |
Golden Rice
- Problem: Vitamin A deficiency (VAD) causes blindness and immune problems — especially in South Asia, Africa.
- Genes: psy (phytoene synthase from daffodil) + crtI (bacterial enzyme).
- Rice endosperm normally lacks beta-carotene — now produces it (golden colour).
- Controversy: GMO food safety concerns; biodiversity concerns.
Bioethics and Biosafety
- GEAC (Genetic Engineering Appraisal Committee) — India's regulatory body for GMO approval.
- Biosafety protocols: Containment facilities, risk assessment.
- TRIPS (Trade-Related Intellectual Property Rights) — impacts on access to biotech products.
- Biopiracy: Unauthorized use of traditional knowledge or biological resources (e.g., basmati rice, turmeric patents — contested by India).
I. Choose the Best Answer
1. The cry gene used in Bt crops is derived from: (a) Agrobacterium tumefaciens   (b) Bacillus thuringiensis   (c) E. coli   (d) Saccharomyces cerevisiae
2. Recombinant human insulin (Humulin) is produced using which organism? (a) Yeast   (b) E. coli   (c) CHO cells   (d) Bacillus subtilis
3. Golden Rice is genetically engineered to produce: (a) Vitamin C   (b) Vitamin K   (c) Beta-carotene (pro-Vitamin A)   (d) Iron
4. Which gene was introduced in Golden Rice for beta-carotene synthesis? (a) cry1Ac   (b) psy and crtI   (c) GFP   (d) Bt toxin gene
5. The Hepatitis B vaccine is produced using: (a) E. coli   (b) Yeast (Saccharomyces cerevisiae)   (c) CHO cells   (d) Transgenic mice
6. Dolly the sheep was produced by: (a) Gene splicing   (b) Somatic cell nuclear transfer (SCNT)   (c) IVF   (d) Embryo splitting
7. GEAC stands for: (a) Genetic Engineering Approval Council   (b) Genetic Engineering Appraisal Committee   (c) Genetic Evaluation and Assessment Committee   (d) Genomic Engineering Advisory Council
8. Rosie the transgenic cow produces milk enriched with: (a) Human growth hormone   (b) Human alpha-lactalbumin   (c) Beta-carotene   (d) Interferon
9. In Bt crops, the Cry protein becomes activated in the insect gut because: (a) Low temperature   (b) Acidic pH   (c) Alkaline pH   (d) Presence of oxygen
10. The Flavr Savr tomato was engineered using: (a) Cry gene   (b) Antisense RNA for polygalacturonase   (c) GFP gene   (d) Beta-carotene genes
11. Which of the following is a concern about transgenic crops? (a) Gene flow to wild relatives   (b) Increased pesticide use   (c) Lower yield   (d) Reduced biodiversity in the gene itself
12. The first clinical case of gene therapy treated: (a) Cystic fibrosis   (b) ADA deficiency (SCID)   (c) Haemophilia   (d) Sickle cell anaemia
II. Fill in the Blanks
1. The cry gene encodes crystal proteins called delta-endotoxins that are toxic to insect larvae. 2. Recombinant insulin is produced by inserting the A and B chain genes into E. coli plasmids. 3. Dolly the sheep was cloned using somatic cell nuclear transfer (SCNT) technique. 4. Golden Rice contains the psy gene from daffodil and the crtI gene from a bacterium. 5. The regulatory body in India that approves GM crops is GEAC (Genetic Engineering Appraisal Committee). 6. Hepatitis B vaccine is produced by expressing the HBsAg gene in yeast cells. 7. Flavr Savr tomato uses antisense RNA technology to inhibit polygalacturonase and delay ripening. 8. Biopiracy refers to the unauthorized commercial use of traditional knowledge or biological resources. 9. In gene therapy for ADA deficiency, a functional ADA gene is inserted into the patient's lymphocytes. 10. The technique that amplifies DNA segments in vitro is called PCR (Polymerase Chain Reaction).
III. True or False
IV. Match the Following
| Column A | Column B |
|---|---|
| 1. Bt cotton | (c) cry1Ac gene |
| 2. Humulin | (f) Recombinant insulin from E. coli |
| 3. Golden Rice | (a) psy + crtI genes |
| 4. Dolly sheep | (g) Somatic cell nuclear transfer |
| 5. Flavr Savr tomato | (e) Antisense RNA technology |
| 6. Hepatitis B vaccine | (b) HBsAg from yeast |
| 7. ADA deficiency | (d) First gene therapy case |
| 8. Rosie cow | (h) Alpha-lactalbumin in milk |
V. Answer Briefly (2-Mark)
1. What is the difference between a transgenic organism and a cloned organism? A transgenic organism carries a foreign gene (transgene) from a different species inserted using genetic engineering — e.g., Bt cotton with the cry gene. A cloned organism is a genetic copy of another individual produced through techniques like SCNT — e.g., Dolly the sheep. Cloning does not involve introducing foreign DNA; transgenics does.
2. Explain why Bt toxin does not kill the plant that produces it. Bt toxin is produced as an inactive protoxin (crystal protein) in the plant. It becomes activated only in the alkaline pH environment of the insect gut. Since the human and plant gut are acidic, the protoxin remains inactive and harmless to the plant and humans consuming it.
3. What is biopiracy? Give one example. Biopiracy is the unauthorized commercial use of traditional knowledge or biological resources of a country by foreign entities without fair compensation. Example: A US patent on turmeric's wound-healing properties was granted but later contested and revoked by India, as turmeric use was traditional knowledge documented in ancient Ayurvedic texts.
4. How is Hepatitis B vaccine produced using recombinant DNA technology? The gene encoding the Hepatitis B surface antigen (HBsAg) is inserted into yeast (Saccharomyces cerevisiae). The yeast expresses HBsAg protein, which self-assembles into virus-like particles. These particles are purified and used as the vaccine — they elicit an immune response without containing live virus, making the vaccine safe.
5. List two advantages and two concerns of Bt crops. Advantages: (1) Reduced pesticide use — farmers spray less chemical insecticide, lowering costs and environmental pollution. (2) Higher yield — pest damage is minimised, improving crop productivity. Concerns: (1) Gene flow — the cry gene may transfer to wild relatives, creating superweeds. (2) Non-target effects — Bt toxin may affect beneficial insects or soil microorganisms over time.
VI. Answer in Detail (5-Mark)
- Background: Earlier insulin was extracted from pig/cow pancreas — caused allergic reactions in some patients due to minor structural differences.
- Gene synthesis: The A chain (21 amino acids) and B chain (30 amino acids) genes of human insulin are chemically synthesised.
- Cloning: Each chain gene is inserted into a separate plasmid vector (using restriction enzymes and DNA ligase) and transformed into E. coli.
- Expression: E. coli produces the insulin A and B chains separately as fusion proteins.
- Extraction and assembly: The chains are extracted, chemically treated to remove the fusion partner, and then combined by forming disulphide bonds between the A and B chains.
- Advantage: No allergic reactions; unlimited supply; identical to human insulin.
- Definition: Gene therapy is the introduction of a normal functional gene into a patient's cells to correct a genetic defect.
- ADA deficiency: Adenosine Deaminase (ADA) deficiency causes Severe Combined Immunodeficiency (SCID) — the patient's immune system is non-functional.
- Procedure: (i) Lymphocytes are isolated from the patient's blood. (ii) A functional ADA gene is inserted into a retroviral vector. (iii) The vector infects the lymphocytes ex vivo, delivering the ADA gene. (iv) Engineered lymphocytes are infused back into the patient.
- Limitations: (i) It is not a permanent cure — repeated infusions are needed because lymphocytes have a limited lifespan. (ii) Does not correct the germline, so the defect can still be inherited. (iii) Risk of insertional mutagenesis — the vector may disrupt other genes. (iv) Immune reactions to the viral vector are possible. (v) Very expensive and still largely experimental.
Worked Examples
Example 1 — Bt cotton (model answer)
A gene (cry gene) from the bacterium Bacillus thuringiensis is inserted into cotton. The plant then makes the Bt toxin in its own cells; when a pest (bollworm) eats the plant, the toxin destroys its gut and kills it — so the plant is pest-resistant without external spraying.
Example 2 — Applications of biotechnology
Example 3 — Gene therapy (model answer)
Gene therapy corrects a defective gene by inserting a normal functional gene into the patient's cells. The first clinical case treated ADA deficiency (a form of SCID) by giving the patient cells carrying a working ADA gene.
Common Mistakes
- Saying Bt protein is a pesticide sprayed — it is produced inside the plant by the inserted gene.
- Forgetting that Dolly was cloned using somatic cell nuclear transfer, not gene splicing.
- Confusing Golden Rice (beta-carotene) with Bt crops (insect resistance) — completely different.
- Not mentioning GEAC when asked about GMO regulation in India.
Common Mistakes to Avoid
- ❌ "Bt toxin is a chemical pesticide sprayed on crops." → ✅ Bt toxin is a protein produced inside the transgenic plant by the inserted cry gene; it is not a chemical spray.
- ❌ "Golden Rice produces Vitamin A directly." → ✅ Golden Rice produces beta-carotene (pro-Vitamin A), which is converted to Vitamin A in the human body.
- ❌ "Gene therapy permanently cures all genetic diseases." → ✅ Gene therapy is largely experimental; ADA deficiency treatment requires repeated infusions and does not correct the germline.
- ❌ "Dolly was a transgenic animal." → ✅ Dolly was a cloned animal produced by SCNT — she carried no foreign gene; she was genetically identical to the donor sheep.
- ❌ "Insulin from E. coli is different from human insulin." → ✅ Recombinant insulin (Humulin) is structurally identical to human insulin; older animal insulin differed slightly and caused allergies.
- ❌ "Bt toxin kills all insects." → ✅ Bt toxin is specific — it targets particular insect orders (Lepidoptera, Diptera, Coleoptera) based on gut receptor binding.
- ❌ "Flavr Savr tomato ripens faster." → ✅ Flavr Savr tomato was engineered to delay ripening and soften more slowly using antisense RNA against polygalacturonase.
- ❌ "GEAC approves all biotech products globally." → ✅ GEAC is India's national regulatory body; other countries have their own agencies (e.g., FDA in the USA, EFSA in the EU).
Exam Checklist
- [ ] Can you define biotechnology and list its major applications in medicine and agriculture?
- [ ] Can you explain the cry gene, Cry protein, and the mechanism of Bt toxin action in insect guts?
- [ ] Can you name at least 3 Bt crops with their target pests and specific cry genes?
- [ ] Can you describe the step-by-step process of recombinant insulin production (Humulin)?
- [ ] Can you explain how Hepatitis B vaccine is produced using yeast?
- [ ] Can you define gene therapy and describe the ADA deficiency case with its limitations?
- [ ] Can you explain Golden Rice — what genes, what pathway, what problem it addresses?
- [ ] Can you distinguish between transgenic, cloned, and knockout organisms with examples?
- [ ] Can you explain SCNT (somatic cell nuclear transfer) as used in cloning Dolly?
- [ ] Can you discuss biopiracy, TRIPS, and the role of GEAC in GMO regulation in India?
- [ ] Can you list benefits and concerns of GM crops (gene flow, superweeds, non-target effects)?
- [ ] Do you know the difference between PCR (amplification) and ELISA (detection) as diagnostic tools?