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Important Questions: CBSE Class 12 Biology Chapter 10 Biotechnology and its Applications

Biotechnology and its Applications is a scoring chapter in CBSE Class 12 Biology that bridges molecular biology with real-world medical, agricultural, and environmental challenges. With a consistent weightage of 7-8 marks, this chapter rewards students who master the specifics of GM crops, transgenic animals, and gene therapy. The 2025 CBSE sample paper included a 5-mark case study on Bt cotton and a 3-mark question on gene therapy for ADA deficiency. This page organizes 18 high-probability questions by marks distribution, complete with model answers that follow the official CBSE marking scheme.

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Key takeaways

✓Chapter 10 Biotechnology and its Applications contributes 7-8 marks in CBSE Class 12 Biology board exam, making it a high-yield chapter for preparation.
✓GM crops (Bt cotton, Golden Rice), transgenic animals, and gene therapy are the three pillars of this chapter that appear in every question paper.
✓5-mark questions often ask for detailed explanations of Bt toxin mechanism, production of transgenic animals, or ADA-SCID gene therapy with diagrams.
✓3-mark questions typically cover applications like insulin production, comparisons between conventional breeding and genetic modification, or ethical issues.
✓1-mark MCQs focus on terminology — cry proteins, biopiracy, biopesticides, transgenic organisms — requiring precise NCERT definitions.
✓Diagram-based questions on Bt cotton mechanism or gene therapy procedure appear frequently and carry 1-2 marks for accurate labelling.
✓Common errors include confusing cry gene variants (Cry1Ac, Cry2Ab, Cry1Ab), mixing up ADA deficiency treatment steps, and incomplete explanations of safety concerns in GMOs.

Chapter Overview and Marks Weightage in CBSE Exam

Chapter 10 Biotechnology and its Applications falls under Unit 5 Biology and Human Welfare in the CBSE Class 12 syllabus. The chapter typically contributes 7-8 marks out of 70 in the Theory paper. Questions are distributed across formats: one 5-mark long-answer or case-based question, one or two 3-mark application-based questions, and 1-2 MCQs in the 1-mark objective section. The 2024 board exam featured a 5-mark question on the production and applications of transgenic animals, plus a 3-mark question comparing traditional hybridisation with recombinant DNA technology in crop improvement. The 2023 paper asked a detailed question on Bt cotton mechanism with a diagram. Examiners favour questions that test conceptual clarity on GM crops (especially Bt cotton and Golden Rice), the process of creating transgenic animals, gene therapy for ADA deficiency, and ethical concerns around GMOs and biopiracy. Understanding the cry gene variants, the role of Agrobacterium tumefaciens as a vector, and the steps of ex vivo gene therapy ensures you cover the high-probability areas.

Typical distribution: one 5-mark, one to two 3-mark, one to two 1-mark questions
High-probability topics: Bt cotton mechanism, transgenic animals for pharmaceutical production, ADA-SCID gene therapy
Diagram questions: Bt toxin activation in insect gut, gene therapy procedure for ADA deficiency
Case-based questions often integrate real-world scenarios like biopiracy or ethical debates on GMO labelling

1-Mark Questions (MCQ and Very Short Answer)

One-mark questions in this chapter test precise NCERT terminology and factual recall. Expect MCQs on the names of cry proteins (Cry1Ac, Cry2Ab, Cry1Ab), the vector used for plant transformation (Agrobacterium tumefaciens), definitions of transgenic organisms, biopesticides, and biopiracy. The 2025 CBSE sample paper included an MCQ asking which cry gene controls cotton bollworm. Very short answer questions may ask you to name the first transgenic cow or state the full form of ADA. These questions reward students who memorise exact NCERT phrasing and can recall specific examples without elaboration. Below are six representative 1-mark questions with concise answers that mirror the board exam style and ensure you cover all subtopics — GM crops, transgenic animals, gene therapy, and ethical issues.

1-Mark Question Bank with Answers

Q1. Name the nematode that infects the roots of tobacco plants and the strategy used to prevent it. A: Meloidogyne incognita; RNA interference (RNAi) using nematode-specific genes to silence mRNA. Q2. Which Bt toxin gene is incorporated in cotton to control bollworms? A: cry1Ac or cry2Ab (both target lepidopteran pests). Q3. Expand ADA and state its significance. A: Adenosine Deaminase; enzyme essential for immune function; deficiency causes SCID. Q4. Name the first transgenic cow and the protein it produced. A: Rosie; produced human alpha-lactalbumin enriched milk. Q5. What is biopiracy? A: Unauthorised use of biological resources and traditional knowledge without compensating the indigenous communities. Q6. State one advantage of using Bt cotton over chemical pesticides. A: Reduces dependence on chemical insecticides, lowering environmental pollution and cost for farmers. These questions are lifted directly from past board papers and CBSE sample papers, ensuring you practice exactly what examiners ask.

2-Mark Questions with Model Answers

Two-mark questions require brief explanations with two distinct points or one point with an example and justification. Common themes include comparisons (conventional breeding vs genetic modification), describing a single step in a process (ex vivo gene therapy), or naming and explaining one application. The CBSE marking scheme awards one mark per valid point, so structure your answer in two clear sentences. Examiners often ask about the advantages of genetically modified crops, the role of specific cry proteins, or the principle behind RNA interference. Below are four high-probability 2-mark questions from past papers and NCERT exemplar, each with a model answer that students can adapt for their board exam. Always underline or highlight key terms like 'Bt toxin,' 'Agrobacterium tumefaciens,' and 'RNA interference' to signal to the examiner that you understand the core concept.

2-Mark Question Bank with Answers

Q1. How does the Bt toxin gene protect cotton plants from bollworm attack? A: The Bt toxin gene (cry gene) from Bacillus thuringiensis is incorporated into cotton. When bollworm larvae ingest Bt toxin, the alkaline pH in their gut converts the inactive protoxin into active toxin, which binds to midgut epithelial cells, creating pores that cause cell lysis and insect death. Q2. Distinguish between gene therapy and conventional treatment for ADA deficiency. A: Gene therapy introduces a functional ADA gene into patient lymphocytes to produce the enzyme permanently, addressing the root cause. Conventional treatment involves enzyme replacement therapy or bone marrow transplant, which are temporary or risky. Q3. Why are transgenic animals used in testing the safety of vaccines? A: Transgenic animals carry genes that make them susceptible to the same diseases as humans, allowing researchers to test vaccine efficacy and safety in a controlled biological system before human trials. Q4. What is biopesticide? Give one example. A: Biopesticides are biological agents or their products used to control pests. Example: Bacillus thuringiensis produces Bt toxin used as a microbial biopesticide against lepidopteran and coleopteran insects.

3-Mark Questions with Model Answers

Three-mark questions demand structured explanations with three distinct points, a comparison table, or a process described step-by-step. Popular topics include the mechanism of Bt toxin action, the production process of transgenic animals, ethical concerns in GMO use, and the complete procedure for gene therapy in ADA-SCID patients. The CBSE marking scheme typically allocates one mark per valid point, so aim for three clear sentences or a labelled diagram worth one mark plus two points. In the 2023 All India paper, a 3-mark question asked students to explain how nematode resistance is introduced in tobacco plants using RNA interference. Another recurring question compares Golden Rice with normal rice and justifies its biofortification role. Model answers should use NCERT language verbatim where possible — terms like 'dsRNA,' 'nematode-specific genes,' 'sense and antisense RNA' are direct lifts from the textbook. Below are four representative 3-mark questions with full worked answers.

3-Mark Question Bank with Answers

Q1. Explain the process of RNA interference used to develop pest-resistant plants. A: (i) A nematode-specific gene is introduced into the host plant using Agrobacterium vectors. (ii) The introduced gene produces both sense and antisense RNA in the host cells. (iii) These two RNA strands are complementary and bind to form double-stranded RNA (dsRNA), which initiates RNAi and silences the nematode mRNA, preventing parasite survival. Q2. How is human insulin produced using recombinant DNA technology? A: (i) Human insulin gene has two chains A and B; these are introduced separately into E. coli using plasmids. (ii) Bacteria produce insulin chains as proinsulin; chains are extracted and purified. (iii) Chains A and B are combined and linked by disulfide bonds to form functional human insulin (Humulin). Q3. What are transgenic animals? Mention two applications. A: Transgenic animals are organisms whose DNA has been altered by introducing a foreign gene. Applications: (i) Producing biological products (e.g. Rosie the cow produced human protein-enriched milk). (ii) Disease models for studying human diseases like cancer and Alzheimer's. Q4. State three ethical concerns associated with GMO use in agriculture. A: (i) Potential allergenicity and unknown long-term health effects on humans. (ii) Gene flow from GM crops to wild relatives may create superweeds. (iii) Biopiracy and exploitation of indigenous knowledge without benefit-sharing with local communities.

5-Mark Questions and Case-Based Questions with Model Answers

Five-mark questions are the foundation of scoring in this chapter. They require detailed explanations, often with a labelled diagram worth 1-2 marks. Typical formats include: Explain the production of a transgenic animal with a flow chart; Describe gene therapy for ADA deficiency with a diagram; Compare and contrast Bt cotton with conventional cotton, discussing benefits and concerns. Case-based questions present a real-world scenario — for example, a passage on Golden Rice biofortification followed by sub-questions on β-carotene synthesis, ethical issues, and comparison with Vitamin A supplementation. The CBSE 2024 paper carried a 5-mark case study on biopiracy and the Basmati patent dispute. Answers should be structured in five distinct points or three points plus a diagram. Always start with a definition or introduction, then describe the process step-by-step, and conclude with significance or limitations. Use subheadings or bullet points to make the answer easy for the examiner to mark. Below are three high-probability 5-mark questions with full model answers.

5-Mark Question Bank with Model Answers

Q1. Describe the steps involved in the production of genetically modified Bt cotton. Draw a labelled diagram showing the mode of action of Bt toxin in the insect gut. A: Steps: (i) Isolation of Bt toxin gene (cry gene) from Bacillus thuringiensis. (ii) Insertion of cry gene into Ti plasmid of Agrobacterium tumefaciens. (iii) Infection of cotton plant cells with recombinant Agrobacterium; integration of gene into plant genome. (iv) Regeneration of transgenic cotton plants expressing Bt toxin. (v) Field trials and commercial release. Diagram labels: Inactive Bt protoxin in plant tissue → Ingested by bollworm larva → Alkaline gut pH converts to active toxin → Toxin binds to midgut epithelial receptors → Pore formation → Cell lysis → Larva death. Q2. Explain gene therapy for ADA deficiency (SCID). Include a labelled diagram. A: ADA (Adenosine Deaminase) deficiency causes severe combined immunodeficiency (SCID). Gene therapy (ex vivo): (i) Lymphocytes are removed from patient's blood. (ii) Functional ADA cDNA is introduced into lymphocytes using a retroviral vector. (iii) Transformed lymphocytes are cultured and checked for ADA expression. (iv) Cultured cells are returned to patient's blood. (v) Periodic infusions are needed as lymphocytes are not immortal. Diagram: Patient → Blood withdrawal → Lymphocyte isolation → Retroviral vector with ADA gene → Infection → Cultured lymphocytes → Re-infusion into patient. Q3. Write a note on transgenic animals and their applications in biotechnology. A: Transgenic animals are genetically modified organisms with foreign DNA integrated into their genome. Applications: (i) Biological products: Rosie (transgenic cow) produced human alpha-lactalbumin in milk for infant formula. (ii) Disease models: Transgenic mice for cancer, Alzheimer's to study pathology. (iii) Vaccine safety testing: Animals made susceptible to human diseases for pre-clinical trials. (iv) Chemical safety: Toxicity testing of drugs using transgenic models. (v) Basic research: Understanding gene regulation, embryonic development, and protein function. Transgenic technology accelerates drug development and reduces reliance on human trials in early phases.

How CBSE Frames Questions from This Chapter

CBSE examiners favour application-based and analytical questions over rote recall for Chapter 10. The majority of 3-mark and 5-mark questions integrate real-world scenarios: a case on Bt brinjal approval controversy, a passage on gene therapy success stories, or a newspaper excerpt on biopiracy. Diagram-based questions are standard — the 2024 Delhi paper asked for a labelled diagram of Bt toxin activation, and the 2023 All India paper required a flow chart of ex vivo gene therapy. Examiners also test conceptual understanding by asking students to compare two methods (conventional breeding vs recombinant DNA, enzyme replacement vs gene therapy), justify the use of biotechnology in a given context, or evaluate ethical concerns with balanced arguments. The question 'Discuss the potential risks of genetically modified crops to the environment' appeared in 2022 and required students to present both scientific concerns (gene flow, resistance development) and socio-economic issues (biopiracy, farmer dependency on seed companies). Multiple-choice questions often present a scenario and ask for the correct cry gene variant or the appropriate vector for plant transformation. To excel, practice framing answers in points, use NCERT terminology exactly, and always include diagrams where the question says 'explain' or 'describe' — diagrams can fetch you 1-2 marks even if prose is incomplete. Highlight keywords in your answers and keep explanations concise yet complete.

Scenario-based questions integrate real-world biotechnology applications and ethical debates
Diagram questions are compulsory for Bt toxin mechanism and gene therapy procedure
Comparison questions test depth: Bt cotton vs conventional, gene therapy vs enzyme replacement
Case studies often draw from current affairs like GMO labelling laws or patent disputes
Mark distribution: definitions and examples (1 mark), process steps (2-3 marks), diagrams (1-2 marks)

Common Mistakes Students Make in Chapter 10

Students often lose marks in this chapter by confusing the cry gene variants: Cry1Ac controls cotton bollworm and corn borer (lepidopterans), Cry2Ab controls cotton bollworm, and Cry1Ab controls corn borer. Mixing these up costs marks in MCQs and short answers. Another frequent error is incomplete explanation of the Bt toxin mechanism — students write 'Bt toxin kills the insect' without mentioning the alkaline gut pH, conversion from protoxin to active toxin, receptor binding, pore formation, and cell lysis. Similarly, in gene therapy questions, many forget to specify 'ex vivo' and skip the step of culturing transformed lymphocytes before re-infusion. Diagram errors are common: unlabelled arrows, missing steps in flow charts, or reversed sequences in the Bt toxin activation pathway. In ethical questions, students present one-sided arguments instead of balanced discussions; CBSE marking schemes reward students who mention both benefits and concerns. For example, when discussing GMOs, state advantages (reduced pesticide use, higher yield) and concerns (allergenicity, gene flow, biopiracy). Spelling mistakes in scientific terms (Agrobacterium vs Agrobaterium, Meloidogyne vs Melidogyne) can also cost marks. Always revise NCERT spellings. Finally, students often write lengthy paragraphs for 2-mark or 3-mark questions instead of crisp point-wise answers, risking the examiner missing key points. Structure answers in numbered points and underline keywords.

Confusing cry gene variants (Cry1Ac, Cry2Ab, Cry1Ab) and their target pests
Incomplete Bt toxin mechanism: missing alkaline pH, protoxin-to-toxin conversion, pore formation, cell lysis
Omitting 'ex vivo' in gene therapy answers and skipping lymphocyte culture step
Diagram errors: unlabelled parts, missing arrows, reversed sequences in flow charts
One-sided ethical arguments instead of balanced discussions on GMOs and biopiracy
Spelling mistakes in NCERT terms: Agrobacterium, Meloidogyne, adenosine, biopesticide
Lengthy paragraphs instead of point-wise answers, making it hard for examiners to award marks

Revision Strategy and Scoring Tips for This Chapter

Chapter 10 is a high-yield chapter where disciplined revision can add 7-8 marks to your Biology total. Start by memorising the three core NCERT topics: GM crops (Bt cotton, Golden Rice, pest-resistant tobacco), transgenic animals (Rosie, disease models, vaccine testing), and gene therapy (ADA-SCID ex vivo procedure). Create a one-page summary sheet with all cry gene variants, their target pests, and the crops they protect — this alone covers 2-3 marks in MCQs and short answers. Practice drawing and labelling diagrams for Bt toxin activation and gene therapy at least five times so you can reproduce them under exam pressure within 3 minutes. For 5-mark questions, use the PEE structure: Point (definition or introduction), Explanation (step-by-step process with 3-4 points), Example or Diagram (concrete case or labelled figure). This ensures you cover all marking scheme criteria. When revising ethical issues, prepare a two-column table: Benefits vs Concerns for GMOs, transgenic animals, and gene therapy — this helps you write balanced answers. Solve the last five years' board papers and mark your answers against the official CBSE marking scheme available on cbse.nic.in. Focus on past trends: Bt cotton and gene therapy appear every year, while biopiracy and RNA interference rotate every two years. Finally, time yourself — a 5-mark answer should take 8-10 minutes, leaving you room to review. CBSETUTOR.ai offers 24×7 doubt clearing with photo upload and AI-driven practice questions for all Class 12 Biology chapters, including personalised tests on high-probability topics. At ₹999/month for classes 6-12 with a 3-day free trial, it gives you on-demand support whenever you are stuck on transgenic animal production or cry gene mechanisms late at night.

Memorise cry gene variants (Cry1Ac, Cry2Ab, Cry1Ab), targets, and crops in a one-page table
Practice diagrams for Bt toxin activation and ADA gene therapy at least five times before exam
Use PEE structure for 5-mark answers: Point, Explanation (3-4 steps), Example or Diagram
Prepare Benefits vs Concerns tables for GMOs, transgenic animals, and gene therapy for balanced ethical answers
Solve last five years' board papers and check against official CBSE marking schemes
Allocate 8-10 minutes per 5-mark answer, 4-5 minutes per 3-mark, 1 minute per MCQ

Frequently asked questions

How many marks does Chapter 10 Biotechnology and its Applications carry in CBSE Class 12 Biology board exam?+

Chapter 10 typically contributes 7-8 marks out of 70 in the CBSE Class 12 Biology Theory paper. This includes one 5-mark long-answer or case-based question, one or two 3-mark questions, and 1-2 MCQs of 1 mark each.

Which topics from Chapter 10 appear most frequently in board exams?+

Bt cotton (mechanism of Bt toxin, cry genes), gene therapy for ADA deficiency (ex vivo procedure with diagram), and transgenic animals (Rosie, disease models) are the three highest-probability topics. Golden Rice and RNA interference in tobacco also rotate every two years.

What is the difference between Cry1Ac and Cry2Ab genes?+

Both Cry1Ac and Cry2Ab are Bt toxin genes that target lepidopteran pests like cotton bollworm. Cry1Ac is more commonly cited in NCERT for Bt cotton, while Cry2Ab is used for resistance management and controlling evolved pest resistance. Both function through the same alkaline-gut activation mechanism.

Do I need to draw diagrams for Chapter 10 questions?+

Yes, diagram-based questions are standard. The CBSE marking scheme awards 1-2 marks for labelled diagrams in 5-mark answers. Practice drawing the Bt toxin activation pathway (inactive protoxin to active toxin, pore formation) and the ex vivo gene therapy flow chart for ADA deficiency.

How should I prepare ethical questions on GMOs and biopiracy?+

Prepare balanced arguments. For GMOs, list benefits (reduced pesticide use, higher yield, fortification) and concerns (allergenicity, gene flow, biopiracy, farmer dependency). For biopiracy, mention Basmati rice and turmeric patent disputes as examples, and discuss benefit-sharing under biodiversity laws.

What is the correct procedure for ADA gene therapy to score full marks?+

Write: (i) Blood withdrawal from patient, (ii) Lymphocyte isolation, (iii) Introduction of functional ADA cDNA via retroviral vector, (iv) Culturing transformed lymphocytes, (v) Re-infusion into patient, (vi) Periodic infusions needed as lymphocytes have limited lifespan. Include a labelled flow diagram.

How is RNA interference different from Bt toxin mechanism?+

RNAi (used in pest-resistant tobacco) silences specific nematode mRNA by forming dsRNA from sense and antisense strands, blocking parasite gene expression. Bt toxin (used in Bt cotton) is a protein that creates pores in insect gut cells, causing cell lysis. Both are genetic strategies but target pests at different molecular levels.

Can I use examples not mentioned in NCERT for Chapter 10 answers?+

Stick to NCERT examples for board exams: Bt cotton, Golden Rice, Rosie the cow, Meloidogyne incognita in tobacco, ADA-SCID gene therapy. Examiners expect these specific cases. Using non-NCERT examples (like Bt brinjal or CRISPR therapies) may not earn marks unless the question explicitly asks for current applications.

What is the role of Agrobacterium tumefaciens in producing GM crops?+

Agrobacterium tumefaciens is a natural genetic engineer. Its Ti (tumour-inducing) plasmid is used as a vector to transfer desired genes (like cry genes) into plant cells. The plasmid integrates foreign DNA into the plant genome, producing transgenic crops like Bt cotton and pest-resistant tobacco.

How can CBSETUTOR.ai help me prepare for Chapter 10 questions?+

CBSETUTOR.ai provides 24×7 AI-driven doubt solving with photo upload, so you can snap a picture of any Bt toxin diagram or gene therapy flow chart and get step-by-step explanations instantly. It offers personalised practice tests on GM crops, transgenic animals, and gene therapy, tracking your weak areas. At ₹999/month for all subjects across classes 6-12, with a 3-day free trial, it is an affordable on-demand tutor for late-night study sessions before your board exam.

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