Biotechnology and its Applications ISC Class 12 Biology: Notes

What Biotechnology and its Applications is about

Weightage: Biotechnology and its Applications is part of the unit Biotechnology and its Applications, which carries 10 of the 70 marks in the ISC Biology Paper 1 (Theory), shared with 1 other chapter. Questions on it can appear in any section of the paper.Source: CISCE ISC Biology syllabus, examination year 2027, distribution of marks

Key concepts

Micropropagation and somatic hybridisation

Plant tissue culture exploits totipotency: the ability of any plant cell (explant) to regenerate a whole plant on a sterile nutrient medium (carbon source such as sucrose, inorganic salts, vitamins, amino acids and growth regulators such as auxins and cytokinins). Micropropagation: producing thousands of plants in a very short time by tissue culture; each plant is genetically identical to the original (somaclones). Used commercially for tomato, banana, apple and others. Meristem culture: even when a plant is infected with a virus, its meristem (apical and axillary) is free of virus; culturing meristems gives virus-free plants (e.g. banana, sugarcane, potato). Somatic hybridisation: single cells are isolated from plants and their cell walls digested by pectinases and cellulases to give naked protoplasts. Protoplasts of two different varieties or species (e.g. tomato and potato) are fused to form hybrid protoplasts, which grow into somatic hybrids (e.g. pomato, though it lacked all the desired characters). This combines characters of plants that cannot be crossed sexually. Together with genetic engineering, these methods help produce crops tolerant to cold, drought, salt and heat.

Worked example

A banana plantation is infected with a virus. How can a grower obtain healthy plants quickly and in large numbers?

Try it first, then show the solutionSolution

1. Excise the apical or axillary meristem, which is free of virus.
2. Culture it in vitro and micropropagate it to produce thousands of identical virus-free plantlets.

Answer: Meristem culture with micropropagation

Bt crops

Bacillus thuringiensis (Bt) produces proteins that kill certain insects: lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). How the toxin works: Bt forms protein crystals containing an inactive protoxin. When an insect larva eats it, the alkaline pH of the gut solubilises the crystals and converts the protoxin into the active toxin, which binds to the surface of midgut epithelial cells and creates pores, causing cell swelling and lysis, and death of the insect. The bacterium is not killed by its own toxin because the toxin is inactive inside it. Bt genes: the toxin is coded by cry genes; the genes have been isolated and incorporated into crop plants such as cotton and corn. Specificity: proteins coded by cryIAc and cryIIAb control cotton bollworms; cryIAb controls the corn borer. Bt cotton reduces the need for chemical insecticides.

Worked example

Why doesn't the Bt toxin kill the bacterium that makes it, and why does it kill the larva?

Try it first, then show the solutionSolution

1. In the bacterium the toxin exists as an inactive protoxin in crystals.
2. In the larva's alkaline gut the crystals dissolve and the protoxin is activated; the toxin binds midgut cells, makes pores, and the cells swell and burst.

Answer: Inactive protoxin; activated by alkaline gut pH

RNA interference against nematodes

The nematode Meloidogyne incognita infects the roots of tobacco plants, greatly reducing yield. RNA interference (RNAi) is a method of cellular defence in all eukaryotes: it involves silencing a specific mRNA by a complementary double-stranded RNA (dsRNA), which binds to and prevents translation of the mRNA. The source of this dsRNA may be infection by viruses with RNA genomes or mobile genetic elements (transposons) that replicate via an RNA intermediate. Strategy: using Agrobacterium vectors, nematode-specific genes were introduced into the host plant so that both sense and anti-sense RNA strands are produced in the host cells. Being complementary, they form dsRNA, which initiates RNAi and silences the specific mRNA of the nematode. The parasite cannot survive in a transgenic host expressing the interfering RNA, so the plant is protected.

Worked example

Explain how transgenic tobacco plants resist Meloidogyne incognita.

Try it first, then show the solutionSolution

1. Nematode-specific genes were introduced via Agrobacterium so the plant makes sense and antisense RNA, which pair into dsRNA.
2. When the nematode feeds, this dsRNA silences a vital nematode mRNA (RNAi); the protein is not made, and the parasite dies.

Answer: dsRNA silences nematode mRNA (RNAi)

Golden rice and GM crops for stress tolerance

Golden rice is a genetically engineered variety of rice that produces β-carotene (provitamin A) in the grain (endosperm), giving it a golden-yellow colour. It is intended to combat vitamin A deficiency (night blindness, xerophthalmia), common where rice is the staple. Genes for β-carotene biosynthesis (from daffodil and a bacterium) were introduced. Benefits of GM crops: tolerance to abiotic stresses such as cold, drought, salt and heat; reduced reliance on chemical pesticides (pest-resistant crops); reduced post-harvest losses; increased efficiency of mineral usage (prevents early exhaustion of soil fertility); enhanced nutritional value. Concerns: possible allergenicity, gene flow to wild relatives, effects on non-target organisms, and socio-economic issues; hence regulation by GEAC.

Worked example

Why is golden rice so called, and which health problem does it address?

Try it first, then show the solutionSolution

1. Its grains contain β-carotene, which is yellow-orange.
2. β-carotene is converted to vitamin A in the body, combating vitamin A deficiency (night blindness).

Answer: β-carotene colour; vitamin A deficiency

Recombinant insulin and vaccines

Insulin controls blood glucose; adult-onset diabetes is managed with insulin taken at regular intervals. Earlier, insulin was extracted from the pancreas of slaughtered cattle and pigs, which caused allergy or other reactions in some patients. Structure: mature insulin has two short polypeptide chains, chain A (21 amino acids) and chain B (30 amino acids), linked by disulphide bridges. In mammals it is made as a pro-hormone (proinsulin) with an extra stretch, the C-peptide, which must be removed during maturation to give active insulin. Production (Eli Lilly, 1983): two DNA sequences corresponding to chains A and B were prepared and introduced into plasmids of E. coli to produce the chains separately; the chains were extracted and combined by creating disulphide bonds to form human insulin (Humulin). This avoids the problem of removing the C-peptide in bacteria. Recombinant vaccines: genes for antigenic proteins are expressed in bacteria or yeast; e.g. the hepatitis B vaccine is produced from yeast. They are safe (no live pathogen) and produced in large quantities.

Worked example

Why did Eli Lilly make chains A and B of human insulin separately in E. coli instead of making proinsulin and converting it?

Try it first, then show the solutionSolution

1. In the body, proinsulin is processed by removing the C-peptide; E. coli lacks the machinery to do this.
2. So two DNA sequences coding for chains A and B were put into separate plasmids; the chains were extracted and joined by disulphide bonds to give active human insulin.

Answer: Bacteria cannot remove the C-peptide, so the A and B chains are made separately and joined by disulphide bonds

Stem cells, gene therapy and molecular diagnosis

Stem cells: undifferentiated cells that can divide to renew themselves and differentiate into specialised cell types. Embryonic stem cells (from the inner cell mass of the blastocyst) are pluripotent; adult stem cells (bone marrow, umbilical cord blood) are more limited. Applications: regeneration of damaged tissues (spinal injuries, heart muscle), treatment of leukaemia by bone-marrow transplantation, diabetes (insulin-producing cells), Parkinson's disease, testing drugs, and studying development. Gene therapy: correcting a gene defect diagnosed in a child or embryo by delivering a normal gene into the person's cells to compensate for the non-functional one. First case (1990): a 4-year-old girl with adenosine deaminase (ADA) deficiency, which causes severe combined immunodeficiency (SCID) because ADA is needed for the immune system. Method: lymphocytes from the patient's blood are grown in culture; a functional ADA cDNA is introduced into them using a retroviral vector; the cells are returned to the patient. Because these cells are not immortal, the patient needs periodic infusions. A permanent cure may be possible if the ADA gene isolated from marrow cells is introduced into cells at early embryonic stages. (Other treatments: bone marrow transplantation, enzyme replacement therapy.) Molecular diagnosis: conventional methods (serum and urine analysis) cannot detect very early infection. PCR amplifies very small amounts of pathogen nucleic acid, detecting HIV in suspected AIDS patients and mutations in suspected cancer patients. DNA/RNA probes: a single-stranded DNA or RNA tagged with a radioactive marker hybridises to its complementary DNA in a clone; detected by autoradiography (a clone with a mutated gene shows no band). ELISA (principle only; technique details not required): based on antigen-antibody interaction; detects the presence of antigens (proteins, glycoproteins) or antibodies synthesised against the pathogen.

Worked example

Why does gene therapy with lymphocytes for ADA deficiency need repeating, and how could a permanent cure be achieved?

Try it first, then show the solutionSolution

1. Genetically corrected lymphocytes are mature cells with a limited lifespan; as they die, ADA levels fall, so periodic infusions are needed.
2. Introducing the functional ADA gene into bone-marrow (stem) cells at an early embryonic stage would give a permanent supply of corrected cells.

Answer: Lymphocytes are not immortal; target stem cells early

Transgenic animals

Transgenic animals have their DNA manipulated to possess and express an extra (foreign) gene. Over 95% of existing transgenic animals are mice; rats, rabbits, pigs, sheep, cows and fish have also been made. Uses: (1) Normal physiology and development: studying how genes are regulated and how they affect body functions (e.g. insulin-like growth factor). (2) Study of disease: models for human diseases such as cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer's, to investigate new treatments. (3) Biological products: medicines can be expensive to make; transgenic animals produce useful biological products by introducing the relevant DNA. α-1-antitrypsin, a human protein used to treat emphysema; products for phenylketonuria (PKU) and cystic fibrosis are being tried. In 1997 the first transgenic cow, Rosie, produced human protein-enriched milk (2.4 g per litre) containing human α-lactalbumin, nutritionally more balanced for human babies than natural cow milk. (4) Vaccine safety testing: transgenic mice are used to test the safety of vaccines before human use (e.g. polio vaccine), replacing monkeys. (5) Chemical safety testing (toxicity testing): animals carrying genes that make them more sensitive to toxic substances give results faster.

Worked example

Suppose Rosie gives 12 litres of milk a day with 2.4 g of human α-lactalbumin per litre. How much of the protein is produced daily, and why is this milk valuable?

Try it first, then show the solutionSolution

1. 12 × 2.4 = 28.8 g per day.
2. Human α-lactalbumin makes the milk nutritionally more balanced for human babies than ordinary cow milk.

Answer: 28.8 g per day; more suitable for infants

Biosafety, GEAC, biopatents, biopiracy and ethics

Manipulating organisms may have unpredictable results when they enter ecosystems. The Indian Government set up the GEAC (Genetic Engineering Appraisal Committee), which makes decisions on the validity of GM research and the safety of introducing GM organisms for public services. Ethical issues: genetic modification of animals may cause them suffering; introducing a gene may disturb the 'integrity' of species; gene flow to wild species; effects on biodiversity; ownership of life forms. Biopatent: a patent granted for biological entities and products derived from them (strains of organisms, cell lines, genetically modified plants and animals, DNA sequences, proteins, and processes). Biopiracy: the use of bio-resources by multinational companies and organisations without proper authorisation from the countries and people concerned, and without compensatory payment. Examples: Basmati rice (India has about 27 documented varieties grown for centuries; in 1997 an American company got patent rights on Basmati rice through the US Patent and Trademark Office, allowing it to sell a 'new' variety in the USA and abroad, derived from Indian farmers' varieties crossed with semi-dwarf varieties); turmeric (a US patent on its wound-healing use was challenged by India's CSIR with ancient texts and revoked); neem (patents on its pesticidal uses challenged). Industrialised nations are rich in finance and technology but poor in biodiversity, while developing nations are rich in biodiversity and traditional knowledge. India has amended its patent laws (Indian Patents Bill) to address these issues and prevent unauthorised exploitation.

Worked example

Define biopiracy and give two examples involving India.

Try it first, then show the solutionSolution

1. Use of bio-resources or traditional knowledge by organisations without authorisation from, or compensation to, the country and people concerned.
2. Basmati rice (US patent, 1997) and turmeric (US patent on wound-healing use, revoked after challenge).

Answer: Unauthorised, uncompensated exploitation; Basmati, turmeric

Biotechnology and its Applications in real life

Each concept, met in an everyday situation. Read the situation, answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Topics in this chapter

• Gene Therapy and Genetically Engineered Insulin
• Bt Cotton and Pest-Resistant Plants
• Transgenic Animals

Biotechnology and its Applications: key facts

Insulin chains

$\text{chain A (21 aa)}+\text{chain B (30 aa)}\stackrel{\text{disulphide bonds}}{\to }\text{insulin}$

C-peptide of proinsulin removed in mammals.

Bt toxin activation

$\text{protoxin}\stackrel{\text{alkaline gut pH}}{\to }\text{active toxin}\to \text{pores in midgut cells}\to \text{lysis}$

Coded by cry genes.

Cry genes and targets

$cryIAc,cryIIAb\to \text{cotton bollworm};cryIAb\to \text{corn borer}$

Specific to insect groups.

RNAi

$\text{sense RNA}+\text{antisense RNA}\to \text{dsRNA}\to \text{silencing of target mRNA}$

Against Meloidogyne incognita in tobacco.

Gene therapy for ADA-SCID

$\text{lymphocytes}+\text{ADA cDNA (retroviral vector)}\to \text{returned to patient}$

Periodic infusions needed.

Rosie's milk

$2.4g{L}^{-1}\text{human }\alpha \text{-lactalbumin}$

First transgenic cow, 1997.

Biotechnology and its Applications: diagrams to practise

Practise each one on paper: draw it from the checklist, then tick off every label.

How the board asks Biotechnology and its Applications

The question patterns to expect, and the method that works for each.

Tricks to remember Biotechnology and its Applications

Short memory aids. Say each one aloud once, then use it on a question the same day.

• Cotton Bollworm: 1Ac and 2Ab

  cryIAc and cryIIAb for cotton; cryIAb for corn.

  Use it when: Bt gene targets.

• Meloidogyne Meets Mute

  RNAi mutes the nematode's mRNA.

  Use it when: RNAi example.

• 21 + 30, held by S-S

  Insulin: A has 21, B has 30 amino acids, linked by disulphides.

  Use it when: Insulin structure.

• ADA = A Day Again

  ADA gene therapy needs repeated infusions.

  Use it when: Gene therapy.

• Basmati, Turmeric, Neem

  BTN: India's biopiracy trio.

  Use it when: Biopiracy examples.

Biotechnology and its Applications: board-level solved questions

Ordered from board level to HOTS. Cover the solution, write your own, then compare step by step.

Case-study practice (Section D style)

Read the situation, then answer every part. In the board paper this is a 5-mark question split into 1 + 1 + 1 + 2 marks.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Where students lose marks in Biotechnology and its Applications

The slips examiners see most often, and what to write instead.

• ✗Mistake: Imprecise pest names

  CISCE examiners' comments, 2024: for the target of cryIAc, candidates wrote 'cotton worm' or 'cotton borer', or only 'bollworm' or 'corn bollworm'.

  Wrong working

  Corn bollworm.

  Right working

  Cotton bollworm.

  ✓Do this: Learn the gene-pest pairs: cryIAc/cryIIAb → cotton bollworm; cryIAb → corn borer.

  Usually costs: 1 mark.

• ✗Mistake: Wrong disease for gene therapy

  CISCE examiners' comments, 2024: candidates named haemophilia, sickle-cell anaemia or AIDS instead of SCID for the first somatic gene therapy to correct an immunodeficiency.

  Wrong working

  AIDS.

  Right working

  SCID caused by ADA deficiency.

  ✓Do this: AIDS is acquired (viral), not a genetic defect treated by gene therapy.

  Usually costs: 1 mark.

• ✗Mistake: Incomplete insulin and streptokinase answers

  CISCE examiners' comments, 2024: candidates did not mention removal of the C-peptide, wrote PCR instead of recombinant DNA technology, wrote sulphur, sulphide or hydrogen bonds instead of disulphide bonds, and for streptokinase said 'to prevent heart attack' without calling it a clot buster.

  Wrong working

  Insulin chains joined by hydrogen bonds; made by PCR.

  Right working

  Joined by disulphide bonds; made by recombinant DNA technology; streptokinase dissolves clots.

  ✓Do this: Use the exact chemical term and technique.

  Usually costs: 1 mark each.

• ✗Mistake: Confusing biopatent with biopiracy

  A frequent confusion: a biopatent is a legal right; biopiracy is exploitation without consent or compensation.

  Wrong working

  Biopiracy is patenting a biological product.

  Right working

  Biopiracy is unauthorised, uncompensated use of bio-resources; a patent may be part of it.

  ✓Do this: Remember the words 'without authorisation and compensation'.

  Usually costs: 1 mark.

Practice questions on Biotechnology and its Applications

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQBoard level

   Golden rice is rich in:
   (a) iron
   (b) β-carotene
   (c) vitamin C
   (d) lysine

   Hint

   Provitamin A.

   Answer

   (b)

2. Q2 · 1 mark · MCQBoard level

   The nematode controlled by RNAi in tobacco is:
   (a) Ascaris
   (b) Wuchereria
   (c) Meloidogyne incognita
   (d) Taenia

   Hint

   Root-knot nematode.

   Answer

   (c)

3. Q3 · 1 mark · Very short answerBoard level

   Name the first transgenic cow and the human protein in its milk.

   Hint

   1997.

   Answer

   Rosie; α-lactalbumin.

4. Q4 · 2 marks · Short answerHarder board level

   α-1-antitrypsin made by transgenic animals is used to treat emphysema. Why is producing it in the milk of transgenic animals better than extracting it from donated human blood?

   Hint

   Quantity, cost, safety.

   Answer

   Large amounts can be collected from milk continuously and cheaply, without depending on blood donors, and there is no risk of transmitting blood-borne infections such as HIV or hepatitis.

5. Q5 · 2 marks · Short answerHarder board level

   Why was insulin from cattle and pigs replaced by recombinant human insulin?

   Hint

   Allergy and supply.

   Answer

   Animal insulin caused allergic and other reactions in some patients (it differs slightly from human insulin) and supply depended on slaughter; recombinant human insulin is identical to human insulin and can be produced in large amounts.

6. Q6 · 2 marks · Short answerBoard level

   What are stem cells? Give two applications.

   Hint

   Self-renewal.

   Answer

   Undifferentiated cells able to divide indefinitely and differentiate into specialised cells. Applications: bone-marrow transplantation for leukaemia; regeneration of damaged tissues (spinal cord, heart); possibly insulin-producing cells for diabetes.

7. Q7 · 2 marks · Short answerHarder board level

   A company wants to release a genetically modified mustard variety for farmers in India. Which body must approve it, and give two concerns that body would examine.

   Hint

   Validity of research; safety for people and environment.

   Answer

   GEAC (Genetic Engineering Appraisal Committee), which judges the validity of GM research and the safety of releasing GM organisms. Concerns: possible allergenicity or toxicity to consumers; gene flow to wild relatives or effects on non-target organisms and biodiversity.

8. Q8 · 2 marks · Short answerBoard level

   Give four advantages of GM crops.

   Hint

   Stress, pests, losses, nutrition.

   Answer

   Tolerance to abiotic stresses (cold, drought, salt, heat); less reliance on chemical pesticides; fewer post-harvest losses; efficient mineral use; enhanced nutritional value (golden rice).

9. Q9 · 2 marks · Short answerHarder board level

   Why are DNA probes radioactive, and how is a mutated gene detected?

   Hint

   Autoradiography.

   Answer

   Radioactivity lets the probe be detected on X-ray film. The probe hybridises with the complementary normal sequence; a clone with a mutated gene does not bind the probe, so no band appears in autoradiography.

10. Q10 · 2 marks · Short answerHarder board level

    Explain the Basmati rice case of biopiracy.

    Hint

    1997 patent.

    Answer

    In 1997 an American company obtained a US patent on Basmati rice lines derived from Indian farmers' varieties crossed with semi-dwarf varieties, allowing it to sell 'new' Basmati abroad without authorisation or benefit to India, which has about 27 traditional Basmati varieties.

11. Q11 · 5 marks · Long answerHarder board level

    (a) Describe the procedure of gene therapy for ADA deficiency. [3]
    (b) Why is ADA deficiency called SCID? [1]
    (c) Name one alternative treatment. [1]

    Hint

    Lymphocytes, retrovirus.

    Answer

    (a) Lymphocytes are taken from the patient's blood and grown in culture; functional ADA cDNA is introduced using a retroviral vector; the corrected lymphocytes are returned to the patient, periodically because they are not immortal. (b) ADA is essential for the immune system; its absence severely impairs both B and T cell function. (c) Bone marrow transplantation or enzyme replacement therapy (ADA injections).

12. Q12 · 2 marks · Short answerHOTS / competency

    A Bt-toxin-producing plant is eaten by a caterpillar and by a cow. Explain why only the caterpillar is harmed.

    Hint

    Gut pH and receptors.

    Answer

    The protoxin is activated only in the alkaline gut of susceptible insect larvae and binds specific receptors on their midgut cells. The mammalian stomach is acidic, the protoxin is digested like other proteins, and mammals lack the receptors, so the cow is unharmed.

13. Q13 · 2 marks · Short answerHOTS / competency

    Suggest why RNAi is described as a natural cellular defence, and why it is highly specific.

    Hint

    Viruses with RNA genomes.

    Answer

    Eukaryotic cells use RNAi to silence dsRNA from RNA viruses and transposons, protecting themselves. Silencing needs base-pairing between the dsRNA and the target mRNA, so only mRNAs with a matching sequence are blocked.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.What is totipotency?Show answer

   The ability of a plant cell to regenerate a whole plant.

2. 2.Name a somatic hybrid.Show answer

   Pomato (potato + tomato).

3. 3.Genes coding Bt toxin?Show answer

   cry genes.

4. 4.Which company produced recombinant human insulin in 1983?Show answer

   Eli Lilly.

5. 5.Number of amino acids in chains A and B of insulin?Show answer

   21 and 30.

6. 6.Expand GEAC.Show answer

   Genetic Engineering Appraisal Committee.

7. 7.Basis of ELISA?Show answer

   Antigen-antibody interaction.

8. 8.Use of transgenic mice in vaccine testing?Show answer

   Testing the safety of vaccines such as polio before human use.

Quick revision checklist

The night before the exam: can you do each of these without looking?

• ☐Can you explain totipotency, somaclones and virus-free plants?
• ☐Can you describe protoplast fusion?
• ☐Can you explain Bt toxin action and name cry genes with targets?
• ☐Can you explain RNAi against Meloidogyne incognita?
• ☐Can you describe insulin production and proinsulin processing?
• ☐Can you outline gene therapy for ADA deficiency?
• ☐Can you list five uses of transgenic animals with examples?
• ☐Can you define biopiracy and give two Indian examples?

Biotechnology and its Applications: frequently asked questions