Biotechnology and its Applications Class 12: Concepts, Diagrams and Board Answers

What Biotechnology and its Applications is about

Weightage: This chapter is part of Unit IX, Biotechnology and its Applications, which carries 12 of the 70 theory marks together with Biotechnology: Principles and Processes.Source: CBSE Biology (044) syllabus 2026-27, course structure, Unit IX Biotechnology and its Applications

In real board papers: asked in 8 of the 8 board papers we hold (2023 to 2026), on average 7.6 marks per paper. See the questions

Key concepts

Plant tissue culture and somatic hybridisation

NCERT section 10.1 Biotechnological Applications in Agriculture (tissue culture)

Why: traditional breeding could not keep pace with demand or improve crops fast enough.

Tissue culture: in the 1950s, scientists found that whole plants could be regenerated from explants (a piece of any plant part, removed and grown in a test tube on a special nutrient medium under sterile conditions).

• Totipotency: the capacity to generate a whole plant from any cell or explant.
• Nutrient medium: a carbon source (sucrose), inorganic salts, vitamins, amino acids and growth regulators such as auxins and cytokinins.

Micropropagation: producing thousands of plants in a short time by tissue culture. All are genetically identical to the original plant: somaclones. Tomato, banana and apple have been produced commercially this way.

Virus-free plants: even in a virus-infected plant, the meristem (apical and axillary) is free of virus. Removing and culturing the meristem in vitro gives virus-free plants; done for banana, sugarcane and potato.

Somatic hybridisation:
1. Isolate single cells and digest their cell walls to get naked protoplasts (bounded by plasma membrane).
2. Fuse protoplasts from two varieties, each with a desirable character, to get hybrid protoplasts.
3. Grow them into new plants: somatic hybrids.

• Example: pomato (tomato + potato), which unfortunately lacked the full combination of desired characters for commercial use.

Worked example

A banana plantation is infected by a virus, and a laboratory must supply 10,000 healthy plantlets of the same variety within a few months. Which part of the plant should be used as the explant, which technique should be used, what are the plantlets called, and what must the culture medium contain? (2 marks)

Try it first, then show the solutionSolution

1. Use the apical or axillary meristem, which stays free of virus even in an infected plant, and grow it in vitro under sterile conditions by micropropagation (tissue culture), which gives thousands of plants in a short time. (1)
2. The plantlets are genetically identical somaclones; the medium needs a carbon source (sucrose), inorganic salts, vitamins, amino acids and growth regulators such as auxins and cytokinins. (1)

Answer: Meristem explant; micropropagation; virus-free somaclones; sucrose, salts, vitamins, amino acids, auxins and cytokinins.

Genetically modified crops

NCERT section 10.1 Biotechnological Applications in Agriculture (GMOs)

Genetically Modified Organisms (GMOs): plants, bacteria, fungi and animals whose genes have been altered by manipulation.

Benefits of GM plants:
1. More tolerant to abiotic stresses (cold, drought, salt, heat).
2. Less reliance on chemical pesticides (pest-resistant crops).
3. Lower post-harvest losses.
4. More efficient mineral use, preventing early exhaustion of soil fertility.
5. Better nutritional value, e.g. golden rice (vitamin A-enriched rice).
6. Tailor-made plants supplying industries with starches, fuels and pharmaceuticals.

Concerns (from the ethics section): genetically modified organisms may give unpredictable results when introduced into ecosystems, so their safety must be assessed (in India by GEAC); patents on GM products and traditional varieties raise issues of fairness.

Comparison of options: agrochemical farming is costly and polluting; organic farming avoids chemicals; GM crops can raise yield and reduce chemical use but need biosafety regulation.

Worked example

List four ways in which genetic modification has helped crop plants, and one reason GM crops need regulation. (2 marks)

Try it first, then show the solutionSolution

1. Tolerance to abiotic stresses; reduced pesticide use; reduced post-harvest losses; better mineral use; improved nutrition such as golden rice (any four). (1)
2. GM organisms can have unpredictable effects when released into ecosystems, so bodies like GEAC check their safety. (1)

Answer: Stress tolerance, pest resistance, fewer post-harvest losses, better nutrition; regulation because of unpredictable ecological effects.

Bt cotton and cry genes

NCERT section 10.1 (Bt Cotton)

Bacillus thuringiensis (Bt): some strains make proteins that kill certain insects:

• lepidopterans (tobacco budworm, armyworm),
• coleopterans (beetles),
• dipterans (flies, mosquitoes).

Mechanism of the Bt toxin (flow chart):
1. B. thuringiensis forms protein crystals during a particular phase of growth; they contain a toxic insecticidal protein.
2. In the bacterium, the toxin exists as an inactive protoxin, so it does not kill the bacterium.
3. An insect eats the crystals.
4. The alkaline pH of the insect gut solubilises the crystals and activates the toxin.
5. Active toxin binds to the surface of midgut epithelial cells and creates pores.
6. Cells swell and lyse; the insect dies.

Bt crops: specific Bt toxin genes were isolated and put into crops, giving insect resistance without insecticides (in effect a bio-pesticide). Examples: Bt cotton, Bt corn, rice, tomato, potato, soyabean.

cry genes: the toxin is coded by genes named cry. Most Bt toxins are insect-group specific, so the gene is chosen to suit the crop and target pest:

• cryIAc and cryIIAb → control cotton bollworms.
• cryIAb → controls corn borer.

The proteins coded are called Cry proteins.

Worked example

Why does the Bt toxin not kill Bacillus thuringiensis itself but kills the bollworm that eats Bt cotton? (3 marks)

Try it first, then show the solutionSolution

1. In the bacterium the toxin exists as an inactive protoxin in protein crystals, so it does not harm the bacterium. (1)
2. In the bollworm's gut the alkaline pH solubilises the crystals and converts the protoxin into the active toxin. (1)
3. The active toxin binds to midgut epithelial cells and creates pores, causing swelling, lysis and death of the insect. (1)

Answer: Inactive protoxin in the bacterium; activated by alkaline insect gut; makes pores in midgut cells.

Pest-resistant plants by RNA interference

NCERT section 10.1 (Pest Resistant Plants)

The pest: the nematode Meloidogyne incognita infects the roots of tobacco plants and greatly reduces yield.

RNA interference (RNAi): a method of cellular defence in all eukaryotic organisms. A specific mRNA is silenced because a complementary double-stranded RNA (dsRNA) binds to it and prevents its translation. Natural sources of such complementary RNA: infection by RNA viruses or transposons (mobile genetic elements) that replicate via an RNA intermediate.

Strategy (flow chart):
1. Using Agrobacterium vectors, nematode-specific genes were introduced into the tobacco plant.
2. The DNA was introduced so that it produced both sense and anti-sense RNA in the host cells.
3. These two complementary RNAs formed dsRNA.
4. dsRNA initiated RNAi, silencing the specific mRNA of the nematode.
5. The parasite could not survive in the transgenic host; the plant was protected.

NCERT's figure compares roots of a control plant (damaged) with transgenic roots 5 days after deliberate nematode infection (protected).

Worked example

Explain how RNA interference was used to protect tobacco plants from Meloidogyne incognita. (3 marks)

Try it first, then show the solutionSolution

1. Nematode-specific genes were introduced into tobacco using Agrobacterium vectors, arranged to make both sense and anti-sense RNA. (1)
2. The complementary sense and anti-sense RNAs paired into dsRNA, which triggered RNAi. (1)
3. RNAi silenced the specific mRNA of the nematode (no translation), so the parasite could not survive in the transgenic roots. (1)

Answer: Sense + anti-sense RNA → dsRNA → RNAi silences nematode mRNA → parasite dies.

Genetically engineered insulin and recombinant vaccines

NCERT section 10.2 Biotechnological Applications in Medicine (10.2.1 Genetically Engineered Insulin); 7.2.4 (recombinant vaccines)

Recombinant therapeutics: rDNA technology enables mass production of safe and more effective drugs. Being identical to human proteins, they do not cause unwanted immune responses (common with products from non-human sources) and are free from infection risk. About 30 recombinant therapeutics have been approved for human use worldwide; 12 are marketed in India.

The insulin problem: adult-onset diabetes is managed by taking insulin regularly. Earlier insulin came from the pancreas of slaughtered cattle and pigs; some patients developed allergy or other reactions to this foreign protein.

Structure and maturation:

• Insulin has two short polypeptide chains, A and B, linked by disulphide bridges.
• In mammals it is made as a pro-hormone (pro-insulin) with an extra stretch, the C peptide, which is removed during maturation.
• The main challenge was getting insulin assembled into the mature form.

Eli Lilly (1983):
1. Prepared two DNA sequences corresponding to the A and B chains of human insulin.
2. Introduced them into plasmids of E. coli to produce the chains.
3. Chains A and B were produced separately, extracted, and combined by creating disulphide bonds to form human insulin.

Why not by mouth? Insulin is a protein, so it would be digested by proteases in the gut (it is injected).

Recombinant vaccines (link to Chapter 7): rDNA technology produces antigenic polypeptides of a pathogen in bacteria or yeast, allowing large-scale production and greater availability, e.g. hepatitis B vaccine produced from yeast.

Stem cell technology (syllabus term): NCERT notes (Chapter 2) that the inner cell mass of the blastocyst contains stem cells with the potency to give rise to all tissues and organs; this ability is what stem cell technology aims to use.

Worked example

How did Eli Lilly overcome the problem of assembling mature human insulin in bacteria? Why is recombinant insulin preferred to animal insulin? (3 marks)

Try it first, then show the solutionSolution

1. Insulin is made naturally as pro-insulin with a C peptide that must be removed; bacteria cannot do this processing. (1)
2. Eli Lilly made separate DNA sequences for chains A and B, expressed them in E. coli plasmids, extracted the chains and joined them by disulphide bonds. (1)
3. Recombinant human insulin is identical to the human hormone, so it does not cause the allergy or immune reactions seen with insulin from cattle and pigs. (1)

Answer: Separate A and B chains made in E. coli and joined by disulphide bonds; no allergic reactions, unlike animal insulin.

Gene therapy

NCERT section 10.2.2 Gene Therapy

Gene therapy: a collection of methods to correct a gene defect diagnosed in a child or embryo. Genes are inserted into a person's cells and tissues to treat a disease; a normal gene is delivered to take over the function of, and compensate for, the non-functional gene. Viruses that insert their genes into hosts are used as vectors.

First clinical gene therapy (1990): a 4-year-old girl with adenosine deaminase (ADA) deficiency.

• ADA is crucial for the immune system; the disorder is caused by deletion of the ADA gene.
• Older treatments: bone marrow transplantation (in some children) or enzyme replacement therapy (injecting functional ADA). Neither is completely curative.

Steps of ADA gene therapy:
1. Lymphocytes from the patient's blood are grown in culture outside the body.
2. A functional ADA cDNA is introduced into them using a retroviral vector.
3. The engineered lymphocytes are returned to the patient.
4. These cells are not immortal, so the patient needs periodic infusions.

Permanent cure: if the ADA gene isolated from marrow cells were put into cells at early embryonic stages, the cure could be permanent.

Worked example

Why does a patient treated by ADA gene therapy need repeated infusions, and how could a permanent cure be achieved? (2 marks)

Try it first, then show the solutionSolution

1. The corrected lymphocytes carrying functional ADA cDNA are not immortal; as they die, new engineered lymphocytes must be infused periodically. (1)
2. Introducing the ADA gene (isolated from marrow cells) into cells at an early embryonic stage would give a permanent cure. (1)

Answer: Engineered lymphocytes die, so infusions repeat; inserting the gene at early embryonic stages could cure permanently.

Molecular diagnosis

NCERT section 10.2.3 Molecular Diagnosis

Conventional diagnosis (serum and urine analysis) cannot detect disease early. By the time symptoms appear, the pathogen's concentration is already very high.

Techniques for early diagnosis:
1. PCR: amplifies the nucleic acid of a pathogen present at very low concentration, before symptoms appear. Used routinely to detect HIV in suspected AIDS patients, to detect mutations in genes in suspected cancer patients, and for many other genetic disorders.
2. Probe hybridisation with autoradiography: a single-stranded DNA or RNA tagged with a radioactive molecule (probe) hybridises to its complementary DNA in a clone of cells, detected by autoradiography. A clone with a mutated gene does not appear on the photographic film, because the probe is not complementary to the mutated gene.
3. ELISA (Enzyme Linked Immunosorbent Assay): based on antigen–antibody interaction. Infection is detected by the presence of antigens (proteins, glycoproteins) of the pathogen, or of antibodies made against it.

Why PCR detects tiny amounts: each cycle doubles the target DNA, so even a few copies become millions to billions, enough to detect.

Worked example

A patient may have been exposed to HIV two weeks ago and has no symptoms. Which test can detect the virus at this stage and why? What principle does ELISA use? (2 marks)

Try it first, then show the solutionSolution

1. PCR: it amplifies the very small amount of viral nucleic acid present before symptoms, making it detectable; it is routinely used to detect HIV. (1)
2. ELISA uses antigen–antibody interaction, detecting pathogen antigens or the antibodies made against them. (1)

Answer: PCR amplifies traces of viral nucleic acid; ELISA uses antigen–antibody interaction.

Transgenic animals

NCERT section 10.3 Transgenic Animals

Transgenic animals: animals whose DNA has been manipulated to possess and express an extra (foreign) gene. Transgenic rats, rabbits, pigs, sheep, cows and fish exist, but over 95% of all transgenic animals are mice.

Five uses:
1. Normal physiology and development: study how genes are regulated and affect body functions and development, e.g. insulin-like growth factor: introducing genes from other species that alter its formation reveals its biological role.
2. Study of disease: models for human diseases to test new treatments; transgenic models exist for cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer's.
3. Biological products: medicines with biological products are expensive; transgenic animals can make them, e.g. human α-1-antitrypsin to treat emphysema; attempts for PKU and cystic fibrosis. In 1997, Rosie, the first transgenic cow, produced milk enriched with human protein (2.4 g per litre) containing human alpha-lactalbumin, nutritionally more balanced for human babies than ordinary cow milk.
4. Vaccine safety: transgenic mice test the safety of vaccines (e.g. polio vaccine) before human use; if reliable, they could replace monkeys for testing vaccine batches.
5. Chemical safety (toxicity) testing: animals carrying genes that make them more sensitive to toxic substances are exposed and studied, giving results in less time.

Worked example

What was special about Rosie? How much human protein would 5 litres of her milk contain? (2 marks)

Try it first, then show the solutionSolution

1. Rosie (1997) was the first transgenic cow; her milk contained human alpha-lactalbumin, making it nutritionally more balanced for human babies. (1)
2. At 2.4 g per litre, 5 litres contain 5 × 2.4 = 12 g of human protein. Check: 2.4 + 2.4 + 2.4 + 2.4 + 2.4 = 12. (1)

Answer: First transgenic cow, milk with human alpha-lactalbumin; 12 g in 5 litres.

Ethical issues, biosafety, patents and biopiracy

NCERT section 10.4 Ethical Issues

Need for ethics and biosafety: manipulation of organisms cannot continue without regulation; ethical standards are needed to judge activities that may help or harm living organisms. Genetic modification can have unpredictable results when organisms are introduced into the ecosystem.

GEAC (Genetic Engineering Approval Committee): set up by the Government of India; it judges whether GM research is valid and whether releasing GM organisms for public use is safe.

Patents: using living organisms for food and medicine has created problems with patents. There is public anger that some companies get patents on products and technologies using genetic materials, plants and other bio-resources long identified, developed and used by farmers and indigenous people.

Basmati case:

• India has an estimated 200,000 rice varieties; 27 documented Basmati varieties are grown here, mentioned in ancient texts, folklore and poetry.
• In 1997, an American company got patent rights on Basmati rice from the US Patent and Trademark Office, letting it sell a 'new' Basmati in the US and abroad.
• This variety was actually derived from Indian farmers' varieties (Indian Basmati crossed with semi-dwarf varieties) and claimed as an invention. The patent extended to functional equivalents, so others selling Basmati could be restricted.
• Attempts have also been made to patent uses of Indian traditional herbal medicines, e.g. turmeric and neem.

Biopiracy: when multinational companies or other organisations exploit a country's bio-resources without permission from that country and its people and without paying compensation.

• Industrialised nations: financially rich, but poor in biodiversity and traditional knowledge.
• Developing nations: rich in biodiversity and traditional knowledge, which saves time, effort and money in commercialisation.
• Because of injustice and inadequate benefit sharing, some nations are making laws against unauthorised exploitation. The Indian Parliament cleared the second amendment of the Indian Patents Bill, which takes such issues into account (including emergency provisions and R&D initiatives).

Worked example

Define biopiracy and explain the Basmati patent case as an example. (3 marks)

Try it first, then show the solutionSolution

1. Biopiracy: use of bio-resources by multinational companies and organisations without proper authorisation from, and compensatory payment to, the countries and people concerned. (1)
2. In 1997, an American company got a US patent on Basmati rice; the 'new' variety had been derived by crossing Indian farmers' Basmati with semi-dwarf varieties and was claimed as an invention. (1)
3. The patent covered functional equivalents and could restrict others selling Basmati, though India grows 27 documented Basmati varieties developed over centuries. (1)

Answer: Unauthorised, uncompensated use of bio-resources; the Basmati patent claimed a variety derived from Indian farmers' varieties.

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

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

Biotechnology and its Applications: key facts

cry genes and targets

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

Bt toxins are insect-group specific.

Bt toxin activation

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

Targets lepidopterans, coleopterans and dipterans.

RNAi

$\text{sense RNA}+\text{anti-sense RNA}\to \text{dsRNA}\to \text{mRNA silenced}$

Protects tobacco from Meloidogyne incognita.

Insulin

$\text{pro-insulin}=A+B+C\text{peptide};\text{insulin}=A+B(\text{disulphide bridges})$

Eli Lilly (1983): A and B chains made separately in E. coli.

Key numbers

$\text{transgenic mice}>95\%;\text{Rosie: }2.4\text{g/L};\sim 30\text{recombinant therapeutics (12 in India)}$

Gene therapy first used in 1990 (ADA deficiency).

Tissue culture medium

$\text{sucrose}+\text{inorganic salts}+\text{vitamins}+\text{amino acids}+\text{auxins, cytokinins}$

Micropropagation gives somaclones.

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.

• Bt kills 'LCD' insects

  Lepidopterans (budworm, armyworm), Coleopterans (beetles), Dipterans (flies, mosquitoes).

  Use it when: Target insect groups of Bt toxins.

• cry for cotton: 'IAc and IIAb for Bolls; IAb for Corn'

  cryIAc and cryIIAb → cotton bollworms; cryIAb → corn borer.

  Use it when: Matching cry genes with pests.

• Bt mechanism: 'Eat, Activate, Attach, Bore, Burst'

  Eat crystals → alkaline gut Activates → Attaches to midgut cells → Bores pores → cells Burst.

  Use it when: Writing the Bt toxin mechanism.

• RNAi: 'Sense + Anti-sense = Silence'

  Sense and anti-sense RNA pair into dsRNA, which silences the target mRNA.

  Use it when: RNA interference.

• Transgenic uses: 'Please Do Buy Very Cheap'

  Physiology, Disease models, Biological products, Vaccine safety, Chemical safety.

  Use it when: Five uses of transgenic animals.

• ADA 1990: 'Four-year-old, Lymphocytes, Retrovirus, Repeat'

  First gene therapy in 1990 on a 4-year-old; patient's lymphocytes + ADA cDNA via retroviral vector; periodic infusions.

  Use it when: Gene therapy questions.

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 4-mark question split into 1 + 2 + 1 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: Saying the Bt toxin is active inside the bacterium

  Wrong working

  Bacillus thuringiensis is resistant to its own toxin.

  Right working

  The toxin exists as an inactive protoxin in the bacterium; it becomes active only in the alkaline gut of the insect.

  ✓Do this: Write 'inactive protoxin' and 'alkaline pH of insect gut'.

  Usually costs: 1 mark.

• ✗Mistake: Writing that RNAi destroys the nematode's DNA

  ✓Do this: RNAi silences a specific mRNA (prevents its translation) through complementary dsRNA; DNA is not destroyed.

  Usually costs: 1 mark.

• ✗Mistake: Saying E. coli made pro-insulin which was then processed

  ✓Do this: Eli Lilly made chains A and B separately in E. coli and joined them by disulphide bonds; the C peptide step was avoided.

  Usually costs: 1 mark.

• ✗Mistake: Calling ADA gene therapy a permanent cure

  ✓Do this: Engineered lymphocytes are not immortal, so periodic infusions are needed; only introduction at early embryonic stages could be permanent.

  Usually costs: 1 mark.

• ✗Mistake: Confusing somatic hybridisation with sexual hybridisation

  ✓Do this: Somatic hybridisation fuses naked protoplasts of two plants (e.g. pomato); no gametes are involved.

  Usually costs: ½ to 1 mark.

• ✗Mistake: Defining biopiracy without the 'no authorisation, no compensation' part

  ✓Do this: Biopiracy is use of bio-resources without proper authorisation and without compensatory payment to the countries and people concerned.

  Usually costs: 1 mark.

NCERT exercise guide: Biotechnology and its Applications

What each exercise in the NCERT chapter tests, how to approach it, and a question of the same kind solved step by step. Questions here are written in our own words.

Biotechnology and its Applications: previous year questions

• Asked in 8 of the 8 board papers we hold (2023 to 2026), on average 7.6 marks per paper; 29 questions in all, counting OR alternatives. In 4 of 4 sample papers.

Counted from the real papers on our previous year papers page, not estimated. Average marks are over every board paper we hold, with an OR pair counted once. Chapter tags are ours.

Solved board questions from Biotechnology and its Applications

Real questions from recent papers. Try each one first, then open our step-by-step solution with marks per step.

Every Biotechnology and its Applications question, by year

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

   The first clinical gene therapy was given for:
   (a) cystic fibrosis (b) ADA deficiency (c) haemophilia (d) thalassaemia

   Hint

   1990, a 4-year-old girl.

   Answer

   (b) ADA deficiency

2. Q2 · 1 mark · Assertion-reasonBoard level

   Assertion (A): Recombinant human insulin does not cause allergic reactions.
   Reason (R): It is identical to the insulin made in the human body.
   (a) Both A and R are true and R is the correct explanation of A.
   (b) Both A and R are true but R is not the correct explanation of A.
   (c) A is true but R is false.
   (d) A is false but R is true.

   Hint

   Foreign protein versus human protein.

   Answer

   (a)

3. Q3 · 1 mark · MCQHarder board level

   Rosie, the first transgenic cow, produced milk containing:
   (a) human α-1-antitrypsin (b) human alpha-lactalbumin (c) human insulin (d) human growth hormone

   Hint

   Better for human babies.

   Answer

   (b) human alpha-lactalbumin

4. Q4 · 2 marks · Very short answerBoard level

   What are the components of the medium used for growing an explant in vitro? (2 marks)

   Hint

   Carbon source plus four more.

   Answer

   A carbon source such as sucrose, inorganic salts (1), vitamins, amino acids and growth regulators such as auxins and cytokinins (1).

5. Q5 · 2 marks · Very short answerHarder board level

   What are Cry proteins? Name the organism that produces them and how humans have used them. (2 marks)

   Hint

   cry genes.

   Answer

   Cry proteins are insecticidal proteins coded by cry genes of Bacillus thuringiensis, which kill specific insect groups (1). cry genes have been put into crops such as cotton and corn to make them insect-resistant (Bt crops), reducing insecticide use (1).

6. Q6 · 2 marks · Very short answerBoard level

   List three techniques used for early diagnosis and state why conventional methods fail at this stage. (2 marks)

   Hint

   Symptoms appear late.

   Answer

   Recombinant DNA technology (probes), PCR and ELISA (1). Conventional serum and urine analysis detect infection only after symptoms appear, when the pathogen concentration is already high (1).

7. Q7 · 3 marks · Short answerHarder board level

   Explain how the Bt toxin acts on an insect and why different cry genes are used for different crops. (3 marks)

   Hint

   Group-specific toxins.

   Answer

   The insect eats the inactive protoxin crystals; the alkaline gut pH solubilises and activates them (1). The active toxin binds midgut epithelial cells, makes pores and causes swelling, lysis and death (1). Most Bt toxins are insect-group specific, so the gene is chosen for the crop's pest: cryIAc and cryIIAb for cotton bollworms, cryIAb for corn borer (1).

8. Q8 · 3 marks · Short answerHarder board level

   Describe the steps of gene therapy for ADA deficiency. (3 marks)

   Hint

   Lymphocytes, retrovirus, return.

   Answer

   Lymphocytes from the patient's blood are grown in culture outside the body (1). A functional ADA cDNA is introduced into them using a retroviral vector (1). The engineered lymphocytes are returned to the patient; as they are not immortal, infusions are repeated periodically (1).

9. Q9 · 5 marks · Long answerHarder board level

   (a) Define biopiracy. Why are developing countries vulnerable to it? (2)
   (b) Describe the Basmati patent case and the steps India has taken. (3) (5 marks)

   Hint

   Rich in biodiversity, poor in money.

   Answer

   (a) Biopiracy is the exploitation of bio-resources by multinational companies or other organisations without permission from, or compensation to, the countries and people they belong to (1). Industrialised nations are financially rich but poor in biodiversity and traditional knowledge, whereas developing countries are rich in both, which others can exploit to save time and money (1). (b) India has about 200,000 rice varieties and 27 documented Basmati varieties grown for centuries (1). In 1997 an American company got a US patent on a 'new' Basmati obtained by crossing Indian Basmati with semi-dwarf varieties and claimed as an invention, with rights extending to functional equivalents (1). Attempts have also been made to patent turmeric and neem uses; the Indian Parliament cleared the second amendment of the Indian Patents Bill to address such issues (1).

10. Q10 · 3 marks · Short answerHOTS / competency

    Suppose a crop scientist wants a banana plantation free of a viral disease that has infected all local plants. Suggest a biotechnological method and explain why it works. Will the new plants be genetically varied? (3 marks)

    Hint

    Meristems escape the virus.

    Answer

    Culture the apical or axillary meristem of an infected plant in vitro (1). The meristem remains free of virus, so plants regenerated from it are virus-free; micropropagation then gives thousands of plants quickly (1). They will be somaclones, genetically identical to the source plant, so there is no genetic variation (1).

11. Q11 · 2 marks · Very short answerHOTS / competency

    A patient's blood shows antibodies against a pathogen in an ELISA test, but PCR detects no pathogen nucleic acid. Suggest an explanation. (2 marks)

    Hint

    Past versus present infection.

    Answer

    ELISA can detect antibodies made against the pathogen, which can remain after an infection has been cleared (1). PCR detects the pathogen's nucleic acid itself, so a negative PCR suggests the pathogen is no longer present (a past infection or prior immunisation) (1).

12. Q12 · 2 marks · Very short answerHarder board level

    Why is RNAi described as a natural method of cellular defence? Give its two natural sources of dsRNA. (2 marks)

    Hint

    Viruses and transposons.

    Answer

    RNAi occurs in all eukaryotic organisms and silences specific mRNAs using complementary dsRNA, defending cells against foreign genetic material (1). dsRNA naturally comes from infection by RNA viruses or from transposons that replicate via an RNA intermediate (1).

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 capacity to generate a whole plant from any cell or explant.

2. 2.What are somaclones?Show answer

   Plants produced by micropropagation, genetically identical to the original plant.

3. 3.What is pomato?Show answer

   A somatic hybrid formed by fusing protoplasts of tomato and potato.

4. 4.What is golden rice?Show answer

   Vitamin A-enriched GM rice.

5. 5.Which nematode infects tobacco roots?Show answer

   Meloidogyne incognita.

6. 6.What are natural sources of dsRNA for RNAi?Show answer

   Infection by RNA viruses or transposons that replicate via an RNA intermediate.

7. 7.What is the C peptide?Show answer

   The extra stretch in pro-insulin, removed during maturation into insulin.

8. 8.When and in whom was the first clinical gene therapy given?Show answer

   In 1990, to a 4-year-old girl with ADA deficiency.

9. 9.What does ELISA stand for and what is its principle?Show answer

   Enzyme Linked Immunosorbent Assay; antigen–antibody interaction.

10. 10.Which human protein is made by transgenic animals to treat emphysema?Show answer

    α-1-antitrypsin.

11. 11.What is GEAC?Show answer

    Genetic Engineering Approval Committee, which decides on the validity of GM research and the safety of introducing GM organisms.

12. 12.How many documented Basmati varieties are grown in India?Show answer

    27.

Quick revision checklist

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

• ☐Can you explain totipotency, micropropagation and how virus-free plants are made?
• ☐Can you list five benefits of GM crops?
• ☐Can you explain how Bt toxin kills insects but not the bacterium, and name cry genes for cotton and corn?
• ☐Can you describe how RNAi protects tobacco from Meloidogyne incognita?
• ☐Can you explain how Eli Lilly made human insulin?
• ☐Can you describe ADA gene therapy and why it needs repeated infusions?
• ☐Can you compare PCR, probe hybridisation and ELISA for diagnosis?
• ☐Can you list five uses of transgenic animals and define biopiracy with the Basmati example?

Biotechnology and its Applications: frequently asked questions