NCERT Solutions for Class 12 Biology Chapter 10 Biotechnology and Its Applications
NCERT Solutions for Class 12 Biology Chapter 10 Biotechnology and Its Applications covers Bt Cotton, Pest Resistant Plants (RNAi), Genetically Engineered Insulin, Gene Therapy, Transgenic Animals, Biopiracy, and Ethical Issues (GEAC).
Overview of Topics & Subtopics (Click to Jump)
1. Biotechnological Applications in Agriculture
Short Note:
• Bt Cotton: Soil bacterium Bacillus thuringiensis produces insecticidal Crystal (Cry) proteins. In the alkaline pH of the insect gut, inactive protoxin dissolves and solubilizes, becoming active to bind midgut epithelial cells, causing pores, cell lysis, and death of insect pests (e.g., bollworms).
- cryIAc & cryIIAb genes control cotton bollworms; cryIAb gene controls corn borer.
• RNA Interference (RNAi): Cellular defense mechanism in all eukaryotes. Silences specific mRNA using complementary dsRNA. Used to protect tobacco roots from nematode parasite Meloidegyne incognita using Agrobacterium vectors.
2. Biotechnological Applications in Medicine
Short Note:
• Genetically Engineered Insulin: Human insulin consists of Chain A and Chain B linked by disulphide bonds. Proinsulin has an additional C-peptide. In 1983, Eli Lilly synthesized DNA sequences for chains A and B, introduced them into E. coli plasmids, produced chains separately, and combined them by disulphide bonds.
• Gene Therapy: Collection of methods to correct a genetic defect. First clinical gene therapy was given in 1990 to a 4-year-old girl with Adenosine Deaminase (ADA) deficiency using retroviral vector to introduce functional ADA cDNA into lymphocytes.
• Molecular Diagnosis: Recombinant DNA technology, PCR, and ELISA (Enzyme Linked Immunosorbent Assay) allow early detection of pathogens/diseases before symptoms appear.
3. Transgenic Animals, Biopiracy & Ethical Issues
Short Note:
• Transgenic Animals: Animals whose genome has been manipulated to possess and express a foreign gene. (Over 95% of all existing transgenic animals are mice).
- Applications: Normal physiology study, vaccine safety testing, chemical safety/toxicity testing, and producing biological products (e.g., transgenic cow Rosie (1997) produced human alpha-lactalbumin enriched milk at 2.4 g/L).
• GEAC (Genetic Engineering Approval Committee): Indian government organization that makes decisions regarding the validity of GM research and safety of introducing GM organisms for public services.
• Biopiracy: Use of bio-resources by multinational companies or other organizations without proper authorization or compensation to the countries and people concerned (e.g., patents on Basmati rice, Neem, and Turmeric).
Intext & Conceptual Questions
1. The toxin is produced by Bacillus thuringiensis in an inactive protoxin form (crystalline protein) inside the bacterium, which does not harm the bacterial host cell.
2. When an insect ingests the protoxin, it reaches the insect's midgut where the alkaline pH solubilizes the protein crystals.
3. Proteolytic cleavage converts inactive protoxin into its active toxin form.
4. The active toxin binds to midgut epithelial cells, creating pores that cause cell swelling, lysis, and death of the insect.
| Feature | Proinsulin | Mature Human Insulin |
|---|---|---|
| Structure | Contains Chain A, Chain B, and an extra C-peptide sequence. | Contains only Chain A and Chain B linked together by disulfide bonds. |
| Biological Activity | Incompletely active / Inactive precursor. | Fully functional and active hormone. |
| C-peptide Presence | Present. | Absent (removed during maturation process). |
Textbook Chapter End Exercise Questions
RNA Interference (RNAi): A mechanism of gene silencing in eukaryotic cells where double-stranded RNA (dsRNA) prevents translation of a specific mRNA.
Mechanism in Nematode Protection:
1. Nematode-specific genes are introduced into host plant cells using Agrobacterium vectors.
2. The introduced DNA produces both sense and anti-sense RNA in host cells, forming a complementary double-stranded RNA (dsRNA).
3. The dsRNA initiates RNAi, binding and silencing the specific mRNA of the parasite Meloidogyne incognita.
4. Consequently, the parasite cannot survive in the transgenic host expressing specific interfering RNA.
Gene Therapy: A collection of therapeutic techniques used to repair or compensate for a defective or mutant gene causing a genetic disorder.
Treatment of ADA Deficiency:
1. Lymphocytes from the blood of the patient are grown in a culture outside the body.
2. A functional ADA cDNA is introduced into these lymphocytes using a retroviral vector.
3. The modified lymphocytes are re-infused back into the patient.
4. Since these cells are not immortal, periodic infusion of genetically engineered lymphocytes is required unless embryonic stem cell gene therapy is performed for a permanent cure.
Biopiracy: The unauthorized exploitation or patenting of biological resources and traditional knowledge of developing nations by multinational companies without proper authorization, consent, or compensation.
Example: In 1997, a US company got patent rights on Basmati rice through the US Patent and Trademark Office. This allowed the company to sell a 'new' variety of Basmati, derived from Indian farmers' varieties crossed with semi-dwarf varieties, restricting traditional Indian rice exports.
Read More & Chapter Resources
These short notes are designed for quick revision. Read the main points once, then use the related material below to practise the same chapter. Revising a concept and checking it with questions can make your preparation more focused.