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Biotechnology and its Applications

NCERT Class 12 · Biology Based on NCERT Class 12 Biology textbook · Free CBSE study kit

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Chapter Notes

Overview
This chapter explores the real-world applications of biotechnology, focusing on agriculture and medicine. It explains how genetically modified organisms (GMOs), tissue culture, and recombinant DNA technology are used to increase food production, produce therapeutic drugs like insulin, and develop gene therapies. The one big idea a student must walk away with is that biotechnology offers powerful tools to solve problems in health and food security, but its use raises serious ethical, legal, and environmental concerns that require regulation.
Key Concepts (18)
Biotechnology
Industrial scale production of biopharmaceuticals and biologicals using genetically modified microbes, fungi, plants and animals.
e.g. Production of human insulin using genetically engineered E. coli bacteria.
Totipotency
The capacity of a plant cell/explant to generate a whole plant from any cell/explant.
e.g. A single cell from a carrot root can be grown in a test tube to produce an entire carrot plant.
Explant
Any part of a plant taken out and grown in a test tube under sterile conditions in special nutrient media.
e.g. A small piece of stem or leaf used to start a tissue culture.
Micro-propagation
The method of producing thousands of plants through tissue culture.
e.g. Commercial production of banana, tomato, and apple plants using tissue culture.
Somaclones
Plants produced by micro-propagation that are genetically identical to the original plant from which they were grown.
e.g. All banana plants produced from a single parent plant through tissue culture are somaclones.
Somatic hybridisation
The process of fusing isolated protoplasts from two different varieties of plants, each having a desirable character, to form a new plant.
e.g. Fusion of tomato protoplast with potato protoplast to form a 'pomato' plant.
Genetically Modified Organisms (GMO)
Plants, bacteria, fungi and animals whose genes have been altered by manipulation.
e.g. Bt cotton, golden rice.
Bt toxin
A toxic insecticidal protein produced by the bacterium Bacillus thuringiensis that kills certain insects.
e.g. Bt cotton contains the cryIAc gene which produces a toxin that kills cotton bollworms.
RNA interference (RNAi)
A method of cellular defense in all eukaryotic organisms that involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA.
e.g. Used to protect tobacco plants from the nematode Meloidegyne incognitia by introducing dsRNA that silences nematode-specific genes.
Gene therapy
A collection of methods that allows correction of a gene defect that has been diagnosed in a child/embryo by inserting genes into a person's cells and tissues to treat a disease.
e.g. Treatment of ADA deficiency by introducing a functional ADA cDNA into the patient's lymphocytes using a retroviral vector.
Pro-hormone
An inactive precursor of a hormone that needs to be processed before it becomes a fully mature and functional hormone.
e.g. Pro-insulin contains an extra stretch called the C peptide which is removed during maturation into insulin.
Transgenic animals
Animals that have had their DNA manipulated to possess and express an extra (foreign) gene.
e.g. Transgenic cow Rosie produced human protein-enriched milk containing human alpha-lactalbumin.
Biopiracy
The use of bio-resources by multinational companies and other organisations without proper authorisation from the countries and people concerned without compensatory payment.
e.g. An American company patenting Basmati rice derived from Indian farmer's varieties.
GEAC (Genetic Engineering Approval Committee)
An organisation set up by the Indian Government to make decisions regarding the validity of GM research and the safety of introducing GM-organisms for public services.
e.g. GEAC evaluates the safety of Bt brinjal before its commercial release in India.
ELISA (Enzyme Linked Immuno-sorbent Assay)
A diagnostic technique based on the principle of antigen-antibody interaction used to detect infection by a pathogen.
e.g. ELISA test for detecting HIV antibodies in suspected AIDS patients.
PCR (Polymerase Chain Reaction)
A technique used to amplify very low concentrations of a bacteria or virus nucleic acid for early diagnosis of disease.
e.g. PCR is used to detect HIV in suspected AIDS patients even before symptoms appear.
Probe
A single stranded DNA or RNA, tagged with a radioactive molecule, allowed to hybridise to its complementary DNA in a clone of cells followed by detection using autoradiography.
e.g. A radioactive probe used to detect a mutated gene in a cancer patient.
Cry proteins
Proteins encoded by cry genes (e.g., cryIAc, cryIIAb) from Bacillus thuringiensis that are toxic to specific insect groups.
e.g. CryIAc and cryIIAb control cotton bollworms; cryIAb controls corn borer.
Formulas & Equations (3)
Bt toxin (inactive protoxin) → (alkaline pH of insect gut) → active toxin → binds to midgut epithelial cells → creates pores → cell swelling and lysis → death of insect
Reads as: Bt toxin is ingested as an inactive protoxin, converted to active form by alkaline pH in insect gut, binds to midgut cells, creates pores, causes cell swelling and lysis, leading to insect death.
Variables: No variables; this is a sequence of events.
Use when: When explaining the mechanism of Bt toxin action in pest-resistant crops.
⚠ Students often write that the Bt toxin is active in the bacterium itself; actually it exists as an inactive protoxin and is activated only in the insect gut.
Pro-insulin → (removal of C peptide) → mature insulin (A chain + B chain linked by disulphide bridges)
Reads as: Pro-insulin is processed by removing the C peptide to form mature insulin consisting of A and B chains linked by disulphide bridges.
Variables: No variables; this is a biochemical processing step.
Use when: When explaining the production of human insulin using recombinant DNA technology.
⚠ Students often forget that insulin is first synthesised as a pro-hormone with a C peptide, and think the A and B chains are directly produced separately in the body.
RNAi: dsRNA → binds to complementary mRNA → prevents translation (silencing)
Reads as: Double-stranded RNA binds to complementary mRNA and prevents its translation, resulting in gene silencing.
Variables: dsRNA = double-stranded RNA; mRNA = messenger RNA.
Use when: When explaining the mechanism of RNA interference used to create pest-resistant plants.
⚠ Students often confuse RNAi with gene knockout or think it destroys DNA; it only silences mRNA translation.
How It Works
Micro-propagation via Tissue Culture
  1. Step 1: An explant (any part of a plant) is taken out from the parent plant.
  2. Step 2: The explant is grown in a test tube under sterile conditions in a special nutrient medium containing a carbon source (sucrose), inorganic salts, vitamins, amino acids, and growth regulators (auxins, cytokinins).
  3. Step 3: The explant develops into a whole plant due to totipotency.
  4. Step 4: Thousands of genetically identical plants (somaclones) are produced in a short duration.
💡 The nutrient medium must be sterile and contain growth regulators; the plants produced are genetically identical to the original plant.
Production of Virus-Free Plants using Meristem Culture
  1. Step 1: Identify a plant infected with a virus.
  2. Step 2: Remove the meristem (apical or axillary) because it is free of virus.
  3. Step 3: Grow the meristem in vitro (in a test tube) under sterile conditions.
  4. Step 4: A healthy, virus-free plant is regenerated.
💡 The meristem is virus-free even if the rest of the plant is infected; this is the key principle.
Somatic Hybridisation
  1. Step 1: Isolate single cells from two different plant varieties, each having a desirable character.
  2. Step 2: Digest the cell walls to obtain naked protoplasts (surrounded by plasma membranes).
  3. Step 3: Fuse the protoplasts from the two varieties to get a hybrid protoplast.
  4. Step 4: Grow the hybrid protoplast to form a new hybrid plant (somatic hybrid).
💡 The cell wall is removed before fusion; the resulting plant is called a somatic hybrid, not a sexual hybrid.
Bt Toxin Action in Pest-Resistant Plants
  1. Step 1: Bacillus thuringiensis produces protein crystals containing inactive protoxin during a particular growth phase.
  2. Step 2: An insect ingests the inactive toxin.
  3. Step 3: The alkaline pH of the insect gut solubilises the crystals and converts the inactive protoxin into an active form of toxin.
  4. Step 4: The activated toxin binds to the surface of midgut epithelial cells.
  5. Step 5: The toxin creates pores in the midgut cells, causing cell swelling and lysis.
  6. Step 6: The insect dies.
💡 The toxin is inactive in the bacterium; it is activated only in the insect's alkaline gut. The toxin does not kill the bacterium because it is stored as an inactive protoxin.
RNAi-Mediated Pest Resistance in Plants
  1. Step 1: Identify a nematode-specific gene (e.g., from Meloidegyne incognitia).
  2. Step 2: Using Agrobacterium vectors, introduce the nematode-specific gene into the host plant in such a way that it produces both sense and anti-sense RNA.
  3. Step 3: The sense and anti-sense RNAs are complementary and form double-stranded RNA (dsRNA) in the host cells.
  4. Step 4: The dsRNA initiates RNA interference (RNAi), which silences the specific mRNA of the nematode.
  5. Step 5: The nematode cannot survive in the transgenic host expressing the interfering RNA, thus protecting the plant.
💡 The dsRNA is produced by the host plant, not the nematode; it targets the nematode's mRNA, not the plant's own mRNA.
Production of Genetically Engineered Human Insulin
  1. Step 1: Two DNA sequences corresponding to the A and B chains of human insulin are prepared.
  2. Step 2: These sequences are introduced into separate plasmids of E. coli.
  3. Step 3: The E. coli bacteria produce the A and B chains of insulin separately.
  4. Step 4: The A and B chains are extracted from the bacteria.
  5. Step 5: The chains are combined by creating disulfide bonds to form functional human insulin.
💡 The A and B chains are produced separately and then combined in vitro; the C peptide is not present in the final product because it is removed during maturation of pro-insulin.
Gene Therapy for ADA Deficiency
  1. Step 1: Lymphocytes are isolated from the blood of a patient with ADA deficiency.
  2. Step 2: The lymphocytes are grown in culture outside the body.
  3. Step 3: A functional ADA cDNA is introduced into the lymphocytes using a retroviral vector.
  4. Step 4: The genetically engineered lymphocytes are returned to the patient.
  5. Step 5: The patient requires periodic infusion of such cells because the lymphocytes are not immortal.
💡 This is not a permanent cure because the cells are not immortal; a permanent cure would require introducing the gene into cells at early embryonic stages.
Molecular Diagnosis using PCR
  1. Step 1: A sample (e.g., blood) is taken from a patient suspected of having a disease.
  2. Step 2: The nucleic acid (DNA or RNA) of the pathogen is amplified using PCR.
  3. Step 3: The amplified product is analysed to detect the presence of the pathogen, even at very low concentrations before symptoms appear.
💡 PCR amplifies the pathogen's nucleic acid, not the pathogen itself; it allows detection before symptoms appear.
Molecular Diagnosis using ELISA
  1. Step 1: A sample from the patient is taken.
  2. Step 2: The sample is tested for the presence of antigens (proteins, glycoproteins) of the pathogen or antibodies synthesised against the pathogen.
  3. Step 3: The detection is based on the principle of antigen-antibody interaction.
💡 ELISA detects either antigens or antibodies; it is based on antigen-antibody interaction, not nucleic acid amplification.
Exam Traps — Don't Make These Mistakes
⚠ Confusing totipotency with micro-propagation
✗ Totipotency is the method of producing thousands of plants through tissue culture.
→ Totipotency is the capacity of a cell to generate a whole plant, not the method itself. Micro-propagation is the method that uses totipotency.
✓ Totipotency is the capacity of a plant cell/explant to generate a whole plant. Micro-propagation is the method of producing thousands of plants through tissue culture using totipotency.
⚠ Bt toxin kills the bacterium that produces it
✗ Bt toxin kills the Bacillus thuringiensis bacteria that produce it.
→ The Bt toxin exists as an inactive protoxin inside the bacterium. It is only activated in the alkaline gut of insects, so it does not harm the bacterium.
✓ Bt toxin is produced as an inactive protoxin by Bacillus thuringiensis and does not kill the bacterium. It is activated only in the alkaline pH of the insect gut.
⚠ RNAi silences the plant's own genes
✗ RNA interference silences the genes of the host plant to protect it from nematodes.
→ RNAi silences the specific mRNA of the nematode, not the host plant's genes. The host plant produces dsRNA that targets the nematode's mRNA.
✓ RNA interference silences the specific mRNA of the nematode parasite, preventing its survival in the transgenic host plant.
⚠ Insulin is produced directly as mature insulin in bacteria
✗ Human insulin is produced directly in bacteria by inserting the gene for mature insulin.
→ Human insulin is first synthesised as pro-insulin with a C peptide. In the Eli Lilly method, the A and B chains are produced separately in bacteria and then combined in vitro to form mature insulin.
✓ In the production of human insulin using rDNA technology, the A and B chains are produced separately in E. coli, extracted, and then combined by creating disulfide bonds to form mature insulin.
⚠ Gene therapy for ADA deficiency is a permanent cure
✗ Gene therapy for ADA deficiency provides a permanent cure for the disease.
→ The first gene therapy for ADA deficiency involved introducing a functional ADA gene into lymphocytes, which are not immortal. The patient requires periodic infusion of such genetically engineered lymphocytes. A permanent cure would require introducing the gene into cells at early embryonic stages.
✓ The first gene therapy for ADA deficiency was not a permanent cure because the lymphocytes are not immortal; the patient requires periodic infusion of genetically engineered lymphocytes.
⚠ Confusing somatic hybridisation with sexual hybridisation
✗ Somatic hybridisation is the fusion of male and female gametes from two different plant varieties.
→ Somatic hybridisation involves the fusion of somatic cells (protoplasts) from two different varieties, not gametes. It is an asexual process.
✓ Somatic hybridisation is the fusion of isolated protoplasts (naked cells without cell walls) from two different plant varieties to form a hybrid plant, without involving sexual reproduction.
Compare & Contrast
Method of plant production
Micro-propagation
Somatic hybridisation
Micro-propagation produces thousands of genetically identical plants (somaclones) from a single explant using tissue culture, while somatic hybridisation fuses protoplasts from two different varieties to create a hybrid plant combining characteristics of both.
Mechanism of pest resistance in plants
Bt toxin resistance
RNAi-mediated pest resistance
Bt toxin resistance involves the expression of a bacterial toxin gene (cry) in the plant, producing a protein that kills insects upon ingestion. RNAi-mediated resistance involves the plant producing dsRNA that silences specific mRNA of the pest (e.g., nematode), preventing its survival.
Treatment approach for genetic disorders
Gene therapy
Enzyme replacement therapy
Gene therapy involves inserting a functional gene into the patient's cells to compensate for a defective gene, while enzyme replacement therapy involves injecting the functional enzyme (e.g., ADA) directly into the patient without altering the genetic defect.
Diagnostic technique
PCR
ELISA
PCR amplifies and detects the nucleic acid (DNA/RNA) of a pathogen, allowing detection at very low concentrations. ELISA detects antigens or antibodies based on antigen-antibody interaction, not nucleic acid.
Exam Focus
Marks pattern: 2 MCQs (1 mark each), 1 Very Short Answer (1 mark), 1 Short Answer (2-3 marks), 1 Long Answer (5 marks) — typically totalling 10-12 marks in the board exam.
Most asked: Bt cotton and the mechanism of Bt toxin action · Production of genetically engineered human insulin · Gene therapy for ADA deficiency · RNA interference and pest-resistant plants · Transgenic animals and their applications · Ethical issues and biopiracy (Basmati rice, neem, turmeric patents)
Don't skip: Explain the mechanism of Bt toxin action and its application in Bt cotton (5 marks).; Describe the production of human insulin using recombinant DNA technology (5 marks).; What is gene therapy? Explain with the example of ADA deficiency (5 marks).; What are transgenic animals? List any four reasons for their production (3-5 marks).
One-Line Revision (read aloud before the exam)
  1. Biotechnology involves industrial scale production of biopharmaceuticals and biologicals using genetically modified organisms.
  2. Totipotency is the capacity of a plant cell to generate a whole plant.
  3. Micro-propagation produces thousands of genetically identical plants (somaclones) through tissue culture.
  4. Meristem culture is used to obtain virus-free plants because meristems are free of virus even in infected plants.
  5. Somatic hybridisation fuses protoplasts from two different plant varieties to form a hybrid plant.
  6. Genetically Modified Organisms (GMOs) have altered genes and are used for pest resistance, stress tolerance, and enhanced nutrition.
  7. Bt toxin is produced by Bacillus thuringiensis as an inactive protoxin, activated in the alkaline gut of insects.
  8. Cry genes (e.g., cryIAc, cryIIAb) code for Bt toxins that are insect-group specific.
  9. RNA interference (RNAi) silences specific mRNA by binding complementary dsRNA, preventing translation.
  10. RNAi is used to create nematode-resistant plants by introducing dsRNA that targets nematode-specific genes.
  11. Genetically engineered human insulin is produced by separately expressing A and B chains in E. coli and combining them.
  12. Insulin is synthesised as pro-hormone with a C peptide that is removed during maturation.
  13. Gene therapy involves inserting a functional gene into cells to treat a genetic disorder.
  14. The first gene therapy was given in 1990 to a 4-year-old girl with ADA deficiency using retroviral vectors.
  15. PCR amplifies pathogen nucleic acid for early diagnosis before symptoms appear.
  16. ELISA detects antigens or antibodies based on antigen-antibody interaction.
  17. Transgenic animals have an extra foreign gene and are used to study diseases, produce biological products, and test vaccine safety.
  18. Transgenic cow Rosie produced human alpha-lactalbumin enriched milk.
  19. Biopiracy is the unauthorised use of bio-resources without compensatory payment.
  20. GEAC (Genetic Engineering Approval Committee) regulates GM research and safety in India.
  21. An American company patented Basmati rice derived from Indian farmer's varieties, leading to controversy.
  22. The Indian Patents Bill has been amended to prevent biopiracy and protect traditional knowledge.

MCQs — 10 Questions with Answers

Q1. Which nutrient component is NOT essential for plant tissue culture media?

  • A. Sucrose as carbon source
  • B. Inorganic salts and vitamins
  • C. Growth regulators like auxins and cytokinins
  • D. Atmospheric nitrogen gas ✓

Answer: D — Tissue culture media require inorganic salts (providing nitrogen as nitrates/ammonium salts), not atmospheric nitrogen gas.

Q2. What is the primary reason Bt toxin does not kill Bacillus thuringiensis while it kills target insects?

  • A. Bacillus has a cell wall that blocks the toxin
  • B. The toxin exists as inactive protoxins in the bacterium and requires alkaline pH of insect midgut to activate ✓
  • C. Bacillus produces an antitoxin protein
  • D. The toxin only works on lepidopteran insects, not on bacteria

Answer: B — Bt toxin is synthesized as inactive protoxins in the bacterium's slightly acidic cytoplasm; only the insect's alkaline midgut pH converts protoxins to active toxins that bind midgut cells.

Q3. Which of the following is a somatic hybrid created through protoplast fusion?

  • A. Golden Rice with Vitamin A enrichment
  • B. Bt cotton resistant to bollworms
  • C. Pomato combining tomato and potato characteristics ✓
  • D. Virus-free banana from meristem culture

Answer: C — Pomato is produced by fusing protoplasts of tomato and potato plants, creating a true somatic hybrid; other options are GM crops or micropropagated plants.

Q4. The cry gene cryIAc in Bt crops encodes a protein that specifically targets which pest?

  • A. Corn borer
  • B. Cotton bollworms ✓
  • C. Fruit flies
  • D. Root-knot nematodes

Answer: B — cryIAc and cryIIAb genes code for proteins that control cotton bollworms; cryIAb targets corn borer; toxins are group-specific.

Q5. A plant is infected with a virus, but you want to obtain healthy plants. Which tissue would you culture to ensure virus-free regeneration?

  • A. Mature leaf cells
  • B. Root cortex cells
  • C. Apical and axillary meristems ✓
  • D. Vascular cambium

Answer: C — Meristems remain virus-free even when the rest of the plant is infected, so culturing meristems and regenerating whole plants yields disease-free plants.

Q6. Which mechanism describes how RNA interference (RNAi) prevents pest damage in genetically modified plants?

  • A. Complementary dsRNA binds to pest mRNA and silences it, preventing protein synthesis in the pest ✓
  • B. The plant produces antibodies that kill the pest
  • C. The plant produces Cry toxins that create pores in pest midgut cells
  • D. dsRNA directly damages pest DNA, causing mutations

Answer: A — RNAi uses complementary dsRNA to bind and silence specific mRNA targets, preventing translation of genes essential for pest survival.

Q7. ASSERTION: Somaclones are genetically identical to their parent plant. REASON: Tissue culture uses asexual reproduction from a single explant.

  • A. Both assertion and reason are correct, and reason explains assertion ✓
  • B. Both assertion and reason are correct, but reason does not explain assertion
  • C. Assertion is correct but reason is incorrect
  • D. Assertion is incorrect but reason is correct

Answer: A — Somaclones are indeed genetically identical because tissue culture propagates from a single cell asexually without meiosis or sexual fusion.

Q8. A farmer wants to grow pest-resistant crops while reducing pesticide use. Compare Bt toxin crops and RNAi-based crops: which statement is most accurate?

  • A. Bt crops work only on lepidopterans; RNAi works universally on all pests
  • B. Bt toxin works by binding midgut epithelial cells and creating pores; RNAi silences pest mRNA by complementary base pairing ✓
  • C. Both Bt and RNAi crops produce identical pest resistance outcomes
  • D. RNAi is more effective than Bt because it works on nematodes and insects equally

Answer: B — These two biotechnologies use entirely different mechanisms: Bt works through protein toxin binding and cell lysis; RNAi works through mRNA silencing.

Q9. A protoplast fusion experiment combines protoplasts from tomato (high yield, poor taste) and a wild Solanum species (excellent taste, low yield). Calculate the expected outcome in terms of trait inheritance.

  • A. The somatic hybrid will show incomplete dominance for both traits
  • B. The somatic hybrid will contain complete sets of chromosomes from both parents and express both desired traits ✓
  • C. The somatic hybrid will show segregation in the next generation due to meiosis
  • D. The somatic hybrid will be haploid and unable to produce viable fruit

Answer: B — Somatic hybrids retain full chromosome sets from both parents, so they can simultaneously express high yield from tomato and good taste from wild species.

Q10. HOTS: Explain why conventional breeding alone cannot match the speed of food production needed for growing populations, and how Bt crops and tissue culture address this limitation in different ways.

  • A. Conventional breeding produces hybrids; Bt crops and tissue culture directly alter genes without sexual reproduction
  • B. Conventional breeding takes many generations and cannot introduce pest resistance or mass-produce identical plants; tissue culture propagates thousands of identical plants in months while Bt crops eliminate pesticide dependency through genetic modification ✓
  • C. Tissue culture is faster; Bt crops are more nutritious; conventional breeding is cheaper
  • D. Conventional breeding works only in tropical climates; Bt crops and tissue culture work everywhere

Answer: B — Tissue culture achieves rapid asexual propagation of elite varieties; Bt crops provide immediate pest resistance without chemicals; both bypass multi-generational sexual breeding timescales.

Flashcards

What is totipotency in plant tissue culture?

The capacity of a single plant cell or explant to develop into a complete whole plant under sterile conditions with proper nutrient media.

Define micro-propagation.

The technique of producing thousands of genetically identical plants (somaclones) from a single explant in a short time period using tissue culture.

Why does Bt toxin not kill Bacillus thuringiensis itself?

The Bt toxin exists as inactive protoxins in the bacterium; it only becomes active in the alkaline pH of an insect's midgut, not in the bacterial cytoplasm.

What is somatic hybridisation and give one example.

The fusion of protoplasts from two different plant varieties to create a hybrid plant combining both traits; example is pomato (tomato + potato hybrid).

How is a virus-free plant obtained from an infected plant?

The apical and axillary meristems of an infected plant remain virus-free, so these meristems are isolated and cultured in vitro to regenerate disease-free plants.

Name the specific Bt toxin genes and the insect pests they target.

cryIAc and cryIIAb target cotton bollworms; cryIAb targets corn borer; choice depends on crop and target pest.

What are the five main benefits of genetic modification in crops?

Tolerance to abiotic stresses, reduced reliance on pesticides, reduced post-harvest losses, increased mineral efficiency, and enhanced nutritional value.

What is RNA interference (RNAi) and how does it work?

RNAi is a cellular defense mechanism where complementary dsRNA binds to and silences specific mRNA, preventing its translation.

What nutrient components are essential for plant tissue culture media?

Carbon source (sucrose), inorganic salts, vitamins, amino acids, and growth regulators (auxins and cytokinins).

How does Cry protein kill insects after entering the midgut?

Activated Cry protein binds to midgut epithelial cell surfaces, creates pores that cause cell swelling and lysis, ultimately killing the insect.

Important Board Questions

Define totipotency and state one application of tissue culture in agriculture. [2 marks]

Totipotency = capacity of single cell to regenerate whole plant. Application: micro-propagation (somaclones) or virus-free plant recovery from meristem culture.

Explain the mechanism by which Bt toxin kills target insects. Include the role of the cry gene, protoxin activation, and the final cellular effect. [5 marks]

cry gene codes for Cry proteins (protoxins) → inactive in Bacillus neutral/acidic cytoplasm → active in insect alkaline midgut pH → binds midgut epithelial cells → creates pores → cell swelling and lysis → insect death. Show each step linked.

Bt crops and tissue culture are two major biotechnological solutions to food production challenges. Compare their principles, mechanisms, and advantages. How do they together address limitations of conventional agriculture? [6 marks]

Bt crops = genetic modification via cry genes (pest resistance, reduced pesticide use). Tissue culture = asexual propagation via totipotency (rapid multiplication of elite varieties, virus-free recovery, somaclones). Together: Bt solves pest problem genetically; tissue culture solves multiplication speed. Both reduce agrochemical dependence and increase yield without conventional breeding timescales.

Assertion-Reason Questions for Biotechnology and its Applications

Q1. Assertion (A):

Micro-propagation through tissue culture can produce thousands of genetically identical plants in a very short duration.

Reason (R):

Somaclones generated from tissue culture inherit all genetic material from the parent explant, maintaining complete genetic identity.

Answer: A — Both A and R are true, and R is the correct explanation of A — Both the assertion and reason are true. Micro-propagation is indeed rapid and produces somaclones. The reason correctly explains WHY this occurs—genetic identity is maintained because all cells derive from a single explant without genetic recombination. This makes the reason the correct explanation for the assertion.

Q2. Assertion (A):

Meristem culture is used to recover virus-free plants from diseased sources.

Reason (R):

The meristem is rich in dividing cells and can regenerate the entire plant architecture more quickly than other tissues.

Answer: C — A is true but R is false — The assertion is true—meristem culture is specifically used for viral removal. However, the reason is false. The actual reason is that the meristem is naturally free of virus infection (viruses do not reach meristematic tissues), not that it divides faster. This tests whether students understand the biological basis for meristem culture's effectiveness.

Q3. Assertion (A):

Bt toxin is lethal to all insect species equally.

Reason (R):

Different Bt toxins show group-specific activity; cryIAc and cryIIAb target lepidopterans while cryIAb targets Coleoptera.

Answer: D — A is false but R is true — The assertion is false—Bt toxins are NOT lethal to all insects equally; they show insect-group specificity. The reason statement is somewhat confused (cryIAb targets corn borer, not all Coleoptera uniformly as stated). Both parts contain inaccuracies, making this answer 'D'—both are false or misleading.

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Case-Based Questions (CBQ) for Biotechnology and its Applications

Case Study:

A sugarcane farmer in Maharashtra noticed significant virus infections reducing his crop yield by 40%. The sugarcane meristem was identified as virus-free despite the rest of the plant being infected. Scientists removed a 2-3 mm meristematic tissue sample and cultured it in a nutrient medium containing sucrose, inorganic salts, vitamins, and growth regulators (auxins and cytokinins) under sterile conditions. Within 6-8 weeks, healthy virus-free plantlets were regenerated. The farmer is now using this technology to recover his diseased crop and establish a virus-free seed garden.

Q1. Why was meristematic tissue chosen specifically for culture rather than leaf or root tissue from the same diseased plant?

  • A. Meristematic cells divide faster and produce plants quickly
  • B. The meristem is naturally virus-free because viral infections do not reach meristematic tissues, allowing clean plant regeneration ✓
  • C. Meristematic tissue has higher nutrient content than other tissues
  • D. Meristematic cells are larger and easier to manipulate in culture

Answer: B

Q2. Which component(s) of the nutrient medium are essential for supporting the complete development of cultured meristematic tissue into a whole plant?

  • A. Sucrose and inorganic salts only
  • B. Vitamins and amino acids only
  • C. Growth regulators (auxins and cytokinins) only
  • D. Sucrose, inorganic salts, vitamins, amino acids, and growth regulators—all components work together ✓

Answer: D

Q3. The regenerated plantlets from this meristem culture will be genetically identical to the original sugarcane plant. These identical plantlets are called:

  • A. Somaclones ✓
  • B. Somatic hybrids
  • C. GMOs (genetically modified organisms)
  • D. Transgenic plants

Answer: A

Q4. If the farmer now wants to propagate these virus-free plants on a large commercial scale rapidly, which biotechnological approach would be most suitable?

  • A. Conventional seed breeding with the healthy plants
  • B. Micro-propagation through continued tissue culture of the virus-free somaclones ✓
  • C. Inserting Bt genes into the recovered plants for pest resistance
  • D. Somatic hybridisation with another sugarcane variety

Answer: B

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Previous Year Questions (PYQ) for Biotechnology and its Applications

Real CBSE board exam questions from past papers — free to attempt.

CBSE 2026 · Set 57(B) Biology · 3 marks

Expand the term 'ELISA'. On which principle is the 'ELISA' test based? Explain the process.

CBSE 2026 · Set 57/5/3 · 1 mark

C-peptide of human insulin is:

  • a part of mature insulin molecule
  • responsible for formation of disulphide bridges
  • removed during maturation of pro-insulin to insulin
  • responsible for its biological activity

CBSE 2026 · Set 57/1/1 · 1 mark

Assertion (A): The milk produced by transgenic cow 'Rosie' was nutritionally more balanced product for human babies than natural cow milk. Reason (R): It was human protein enriched milk containing human alpha lactaglobulin.

  • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation for Assertion (A).
  • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation for Assertion (A).
  • Assertion (A) is true, but Reason (R) is false.
  • Assertion (A) is false, but Reason (R) is true.

CBSE 2026 · Set 57/1/1 · 3 marks

A farmer grew two varieties of corn crop in field A and B. He grew normal corn crops in field A and GM corn crops in field B. He observed that corn borers attacked only in field A. To control it, spores of Bt were sprayed on field A. (a) Name the gene in the spores responsible for control of pest. (0.5 marks) (b) What effect will the spores of Bt have on insect pest? (1.5 marks) (c) How has corn plants of field B developed resistance against this pest? Explain. (1 mark)

CBSE 2026 · Set 57/1/2 · 3 marks

A farmer grew two varieties of corn crop in field A and B. He grew normal corn crops in field A and GM corn crops in field B. He observed that corn borers attacked only in field A. To control it, spores of Bt were sprayed on field A. (a) Name the gene in the spores responsible for control of pest. (½ mark) (b) What effect will the spores of Bt have on insect pest? (1½ marks) (c) How has corn plants of field B developed resistance against this pest? Explain. (1 mark)

CBSE 2026 · Set 57/1/3 · 1 mark

Pomato was produced by fusing protoplasts of

  • Tomato and Potato
  • Pomegranate and Tomato
  • Pomegranate and Potato
  • Pomegranate, Potato and Tomato

CBSE 2026 · Set 57/1/3 · 3 marks

Suggest and describe a technique through which a healthy sugarcane plant can be obtained from virus infected sugarcane plant.

CBSE 2026 · Set 57/2/1 · 1 mark

Genetically modified tobacco plants were produced using Agrobacterium vectors. Which property of Agrobacterium helps in carrying nematode specific genes into the host plant ?

  • Infectious for monocot plant ; has Ti plasmid
  • Infectious for dicot plant ; has Ti plasmid
  • Infectious for plants and animals ; has Ti plasmids
  • Infectious for monocot and dicot plants ; has cry gene

CBSE 2026 · Set 57/2/2 · 1 mark

Genetically modified tobacco plants were produced using Agrobacterium vectors. Which property of Agrobacterium helps in carrying nematode specific genes into the host plant?

  • Infectious for monocot plant ; has Ti plasmid
  • Infectious for dicot plant ; has Ti plasmid
  • Infectious for plants and animals ; has Ti plasmids
  • Infectious for monocot and dicot plants ; has cry gene

CBSE 2026 · Set 57/2/2 · 3 marks

There are limitations of traditional breeding techniques that led to promotion of micro-propagation. Mention two advantages of micropropagation. Give two examples where it is commercially adopted.

CBSE 2026 · Set 57/2/3 · 2 marks

A patent with Type I diabetes is unable to produce sufficient insulin. (a) How has recombinant DNA technology helped in addressing this problem? (b) Mention its advantage over animal derived insulin.

CBSE 2026 · Set 57(B) Biology · 1 mark

Assertion (A): Organisations like GEAC are necessary to monitor GM researches and to test the safety of introducing Genetically Modified organisms for public services. Reason (R): GM researches can have unpredictable results which can even be disastrous, when Genetically Modified organisms are introduced into the ecosystem.

  • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
  • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
  • Assertion (A) is true, but Reason (R) is false.
  • Assertion (A) is false, but Reason (R) is true.

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