Chapter 10: Biotechnology and its Applications Long Questions | biology Class 12 CBSE

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Chapter 10: Biotechnology and its Applications Long Questions | biology Class 12 CBSE | ByteNotes.in

Long Answer

Medium difficulty • Structured explanation

Medium

Question 1

Long Form

Describe the mechanism by which Bt toxin protects crop plants from insect pests, and explain why Bt toxin is considered a safer alternative to chemical pesticides.

Bt toxin is produced by Bacillus thuringiensis as inactive protoxin crystals during a specific growth phase; the cry genes (e.g., cryIAc, cryIIAb, cryIAb) encode these insect-group-specific proteins.
When an insect ingests the inactive toxin, the alkaline pH of its midgut solubilises the crystals and converts the protoxin into active toxin form.
The active toxin binds to midgut epithelial cell surfaces, creates pores causing cell swelling and lysis, and ultimately kills the insect.
Bt toxin genes are incorporated into crop plants such as Bt cotton and Bt corn using recombinant DNA technology, making the crop itself resistant without applying external pesticides.
Unlike chemical pesticides, Bt toxin is insect-group specific and biodegradable, reducing environmental contamination, non-target organism harm, and the need for expensive chemical inputs — especially beneficial for farmers in developing countries.

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Hard

Question 2

Long Form

Compare the strategies of Bt toxin gene expression and RNA interference (RNAi) as approaches to developing pest-resistant transgenic plants, highlighting the mechanisms and target organisms for each.

Bt toxin strategy uses cry genes from Bacillus thuringiensis inserted into crop plants; the expressed insecticidal Cry protein is activated in the alkaline insect gut and kills insects such as lepidopterans, coleopterans, and dipterans.
RNAi strategy targets nematodes — a dsRNA complementary to nematode-specific mRNA is produced in the host plant using sense and anti-sense constructs delivered via Agrobacterium vectors.
In Bt toxin strategy, the toxin directly disrupts midgut epithelial cells of the pest insect, whereas in RNAi, the silencing of the nematode's essential mRNA prevents its survival in the host plant.
Bt toxin approach is effective against insects that ingest the plant material, while RNAi specifically protects against nematodes such as Meloidogyne incognita that infest plant roots.
Both strategies reduce dependence on chemical pesticides and are crop-specific, but RNAi offers a more targeted gene-silencing mechanism with potential for high specificity against a single parasite species.

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Long Answer

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Medium

Question 3

Long Form

Explain the steps involved in producing human insulin using recombinant DNA technology and describe why this was a significant improvement over earlier insulin sources.

Earlier insulin was extracted from the pancreas of slaughtered cattle and pigs, which caused allergic and immunological reactions in some patients due to minor differences in protein structure.
In 1983, Eli Lilly prepared two DNA sequences corresponding to the A and B polypeptide chains of human insulin and introduced them into separate E. coli plasmids for expression.
The two chains were produced separately in bacterial cultures, extracted, and then combined by creating disulfide bonds between specific cysteine residues to form mature human insulin.
The key challenge was that natural insulin in mammals arises from pro-insulin by enzymatic removal of the C peptide — a processing step that doesn't occur in bacteria — which Eli Lilly circumvented by producing the chains separately.
Recombinant human insulin is structurally identical to natural human insulin, does not trigger immune responses, carries no infection risk from animal sources, and can be produced at industrial scale reliably and cost-effectively.

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Hard

Question 4

Long Form

Explain the procedure followed in gene therapy for ADA deficiency and analyse its limitations compared to a permanent cure.

ADA deficiency is caused by deletion of the adenosine deaminase gene, impairing immune function; the first clinical gene therapy was given in 1990 to a 4-year-old girl with this condition.
Lymphocytes from the patient's blood are cultured outside the body, and a functional ADA cDNA is introduced into them using a retroviral vector that integrates the gene into the lymphocyte genome.
The genetically engineered lymphocytes are returned to the patient, where they produce the ADA enzyme and restore immune function.
The major limitation is that lymphocytes are not immortal; they die over time, requiring the patient to receive periodic infusions of freshly engineered lymphocytes throughout their life.
A permanent cure would require introducing the ADA gene into early embryonic marrow cells, which continuously generate lymphocytes — this would eliminate the need for repeated treatment and provide lifelong immune function.

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Long Answer

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Question 5

Long Form

Discuss the various uses of transgenic animals in scientific research and industry, using specific examples from the chapter.

Transgenic animals are used to study normal physiology and development — for example, introducing genes that alter insulin-like growth factor formation helps understand the factor's biological role in growth regulation.
They serve as disease models for human conditions such as cancer, cystic fibrosis, rheumatoid arthritis, and Alzheimer's, enabling investigation of new treatments in a controlled biological system.
Transgenic animals produce valuable biological products — the transgenic cow Rosie (1997) produced human alpha-lactalbumin-enriched milk (2.4 g/L), which is nutritionally superior to natural cow milk for human babies.
Transgenic mice are used for vaccine safety testing, such as for the polio vaccine, potentially replacing primate testing with a more ethical and cost-effective alternative.
For chemical safety (toxicology) testing, transgenic animals are engineered to be more sensitive to toxic substances, enabling faster and more reliable detection of harmful effects of drugs and chemicals.

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Hard

Question 6

Long Form

Evaluate the ethical issues arising from the genetic manipulation of organisms and the problem of biopiracy, with reference to specific Indian examples.

Genetic modification can have unpredictable ecological consequences when GMOs are introduced into ecosystems, necessitating regulatory oversight by bodies like India's GEAC (Genetic Engineering Approval Committee).
Biopiracy refers to the unauthorised commercial exploitation of bio-resources and traditional knowledge without compensatory payment — a concern especially for biodiversity-rich developing nations.
A prominent example is the 1997 US patent on Basmati rice, derived from Indian farmers' varieties and claimed as a new invention after crossing with semi-dwarf varieties, threatening Indian farmers' rights.
Similarly, attempts have been made to patent traditional Indian herbal medicines such as turmeric and neem, which have been used in India for centuries.
India has responded through the second amendment of the Indian Patents Bill, which includes provisions for emergency use, research protections, and patent terms to safeguard traditional knowledge and bio-resources from foreign exploitation.

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Question 7

Long Form

Describe the contributions of tissue culture techniques to plant biotechnology and explain the concept of totipotency as the biological basis of these techniques.

Totipotency — the capacity of any plant cell or explant to regenerate into a complete organism — is the fundamental biological basis of all plant tissue culture techniques.
Micropropagation uses totipotency to produce thousands of genetically identical somaclones from explants cultured in nutrient media (sucrose, inorganic salts, vitamins, amino acids, auxins, cytokinins) in short durations.
Meristem culture exploits the fact that apical and axillary meristems are virus-free even in infected plants, enabling production of disease-free planting material for crops like banana, sugarcane, and potato.
Isolated protoplasts from two different plant varieties can be fused via somatic hybridisation to create somatic hybrids combining desirable traits; pomato (tomato + potato fusion) is a well-known, though commercially unsuccessful, example.
These techniques have been commercially applied to important food plants like tomato, banana, and apple, and offer vast potential for plant improvement, conservation of rare species, and production of uniform disease-free crops.

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Long Answer

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Hard

Question 8

Long Form

Analyse the molecular diagnostic tools — PCR, DNA probes, and ELISA — in terms of their principles and specific applications in disease detection.

PCR (Polymerase Chain Reaction) amplifies specific nucleic acid sequences exponentially, enabling detection of very low concentrations of pathogen DNA/RNA before disease symptoms appear; it is routinely used to detect HIV in AIDS patients and mutations in cancer patients.
DNA probes are single-stranded DNA or RNA molecules tagged with a radioactive label that hybridise to their specific complementary sequences in a cell clone; non-complementarity with a mutated gene means that clone does not appear on autoradiographic film, identifying it as abnormal.
ELISA is based on antigen-antibody interaction; infection is detected by identifying pathogen antigens (proteins, glycoproteins) or host antibodies raised against the pathogen, and enzyme-linked antibodies produce a detectable colour signal.
Each technique targets different stages: PCR and probes work at the nucleic acid level for genetic or pathogen detection, while ELISA works at the protein level for immune system-based detection.
Together these tools overcome the limitations of conventional serum and urine analysis, providing early, sensitive, and specific diagnosis that is critical for managing diseases before they progress to advanced stages.

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Long Answer

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Hard

Question 9

Long Form

Discuss the advantages of GM crops compared to conventional crops and critically assess the concerns associated with their large-scale adoption.

GM crops offer tolerance to abiotic stresses (cold, drought, salt, heat), allowing cultivation in previously unsuitable regions and improving food security in climate-stressed environments.
Pest-resistant GM crops (e.g., Bt cotton, Bt corn) reduce reliance on expensive chemical pesticides, cutting costs for farmers in developing countries and reducing environmental contamination.
GM crops can reduce post-harvest losses, increase efficiency of mineral use (preventing premature soil exhaustion), and enhance nutritional value (e.g., Vitamin A-enriched golden rice to combat nutritional deficiencies).
Concerns include potential unpredictable ecological consequences when GM organisms are introduced into ecosystems, possible gene flow to wild relatives, and the ethical/legal issues around corporate patents and loss of biodiversity.
The regulatory role of bodies like GEAC in India is critical to ensure that GM crops are rigorously tested before commercial release, balancing the agricultural benefits against ecological and social risks.

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Long Answer

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Hard

Question 10

Long Form

Trace the development of alternatives to conventional agro-chemical-based agriculture, from tissue culture to genetically engineered crops, and assess their contributions to solving food security challenges.

The Green Revolution tripled food supply using better crop varieties, management practices, and agrochemicals (fertilisers, pesticides), but the benefits plateaued and agrochemicals remained too expensive for many developing-world farmers.
Tissue culture emerged as an alternative — micropropagation produces large numbers of uniform, disease-free plants rapidly, and somatic hybridisation enables combining desirable traits from two different species beyond the limits of conventional breeding.
Genetically Modified Organisms (GMOs) represent the next step, directly inserting beneficial genes for stress tolerance, pest resistance, enhanced nutrition (golden rice), and reduced post-harvest losses into crop genomes.
RNAi technology specifically addresses nematode and viral diseases that conventional breeding cannot easily tackle, offering targeted protection without broad-spectrum chemical interventions.
Each technological wave has contributed progressively — tissue culture for rapid, uniform propagation; GMOs for trait-specific engineering — but all approaches require careful evaluation for safety, equity, and ecological sustainability.

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Chapter 10: Biotechnology and its Applications | Long Questions

Describe the mechanism by which Bt toxin protects crop plants from insect pests, and explain why Bt toxin is considered a safer alternative to chemical pesticides.

Compare the strategies of Bt toxin gene expression and RNA interference (RNAi) as approaches to developing pest-resistant transgenic plants, highlighting the mechanisms and target organisms for each.

Explain the steps involved in producing human insulin using recombinant DNA technology and describe why this was a significant improvement over earlier insulin sources.

Explain the procedure followed in gene therapy for ADA deficiency and analyse its limitations compared to a permanent cure.

Discuss the various uses of transgenic animals in scientific research and industry, using specific examples from the chapter.

Evaluate the ethical issues arising from the genetic manipulation of organisms and the problem of biopiracy, with reference to specific Indian examples.

Describe the contributions of tissue culture techniques to plant biotechnology and explain the concept of totipotency as the biological basis of these techniques.

Analyse the molecular diagnostic tools — PCR, DNA probes, and ELISA — in terms of their principles and specific applications in disease detection.

Discuss the advantages of GM crops compared to conventional crops and critically assess the concerns associated with their large-scale adoption.

Trace the development of alternatives to conventional agro-chemical-based agriculture, from tissue culture to genetically engineered crops, and assess their contributions to solving food security challenges.

Unlock all Long Questions