Chapter 21 — Breeding and Biotechnology: Multiple Choice Questions
1. The technique used to produce many copies of a gene is called ______.
Answer
(a) Genetic engineering (b) Polymerase Chain Reaction (PCR) (c) Gel electrophoresis (d) Cloning
✅ Answer: (b) Polymerase Chain Reaction (PCR)
ExplanationPCR (Polymerase Chain Reaction) amplifies (copies) specific DNA sequences millions of times in a few hours. Invented by Kary Mullis (Nobel Prize 1993). Used in: forensics (DNA fingerprinting), medical diagnosis (COVID tests), archaeology (ancient DNA), paternity testing.
2. Bt cotton is genetically modified to be resistant to ______.
Answer
(a) Drought (b) Certain insect pests (bollworm) (c) Fungal diseases (d) Cold temperature
✅ Answer: (b) Certain insect pests (bollworm)
ExplanationBt cotton contains a gene from Bacillus thuringiensis (Bt) that codes for a protein (Cry toxin) toxic to bollworm larvae (Helicoverpa armigera). When pests eat the cotton leaves, they die. This reduces pesticide use. Introduced in India in 2002; now ~95% of Indian cotton is Bt cotton.
3. The insulin used in treating diabetes is now produced using ______.
Answer
(a) Pigs (b) Recombinant DNA technology (bacteria) (c) Sheep (d) Horses
✅ Answer: (b) Recombinant DNA technology (bacteria)
ExplanationHuman insulin is now produced by inserting the human insulin gene into E. coli bacteria. The bacteria then produce human insulin protein in large quantities. This recombinant insulin (Humulin) replaced animal insulin (from pigs/cows), which caused allergic reactions in some patients.
4. The first animal to be successfully cloned was ______.
Answer
(a) A mouse (b) Dolly the sheep (c) A cow (d) A frog
✅ Answer: (b) Dolly the sheep
ExplanationDolly the sheep (1996) was the first mammal to be cloned from an adult somatic cell by Ian Wilmut and colleagues at the Roslin Institute, Scotland. She was a genetic copy of a 6-year-old Finn Dorset ewe. Dolly lived until 2003. Her birth demonstrated that somatic cells could be reprogrammed.
5. The use of microorganisms to clean up environmental pollution is called ______.
Answer
(a) Biofertilisation (b) Bioremediation (c) Biocontrol (d) Biopesticides
✅ Answer: (b) Bioremediation
ExplanationBioremediation: Using living organisms (mainly bacteria and fungi) to break down or detoxify environmental pollutants. Examples:
- Oil-eating bacteria (Pseudomonas) to clean oil spills
- Mercury-resistant bacteria to clean mercury pollution
- Phytoremediation: plants that absorb heavy metals from soil
6. DNA fingerprinting was developed by ______.
Answer
(a) Kary Mullis (b) Alec Jeffreys (c) Gregor Mendel (d) James Watson
✅ Answer: (b) Alec Jeffreys
ExplanationDNA fingerprinting (DNA profiling) was developed by Alec Jeffreys (1984). It analyses specific regions of DNA that vary between individuals. Used in: criminal investigations, paternity testing, identification of disaster victims, immigration disputes. Each person's DNA pattern is unique (except identical twins).
7. The tool used to cut DNA at specific sequences is ______.
Answer
(a) DNA ligase (b) DNA polymerase (c) Restriction endonuclease (d) RNA polymerase
✅ Answer: (c) Restriction endonuclease
ExplanationRestriction endonucleases (restriction enzymes) are "molecular scissors" — they cut DNA at specific nucleotide sequences called restriction sites. Discovered in bacteria (protection against viruses). Essential tools in genetic engineering. Example: EcoRI cuts at GAATTC. DNA ligase joins cut DNA pieces.
8. Tissue culture involves ______.
Answer
(a) Growing microbes in cultures (b) Growing plant cells/tissues in sterile nutrient media (c) Culturing human cells for transplants (d) Fermentation of food
✅ Answer: (b) Growing plant cells/tissues in sterile nutrient media
ExplanationPlant tissue culture (micropropagation) grows plant cells, tissues, or organs in sterile nutrient media (artificial environment). Can produce thousands of genetically identical plants from a small sample. Used to: propagate rare plants, produce virus-free plants, develop genetically modified plants, and conservation of endangered species.
9. Golden rice is genetically modified to contain high amounts of ______.
Answer
(a) Iron (b) Protein (c) Beta-carotene (provitamin A) (d) Vitamin C
✅ Answer: (c) Beta-carotene (provitamin A)
ExplanationGolden rice was engineered by inserting daffodil and bacterial genes to produce beta-carotene (which the body converts to Vitamin A). It was developed to address vitamin A deficiency (VAD), which causes blindness and death in millions of children in developing countries. Golden rice is controversial — debates about GM food safety and distribution.
10. Hybridisation in plant breeding involves ______.
Answer
(a) Crossing two different species or varieties (b) Cloning plants (c) Genetic modification (d) Vegetative propagation
✅ Answer: (a) Crossing two different species or varieties
ExplanationHybridisation is crossing two plants of different genotypes (varieties, species) to combine desirable traits from both parents. Offspring (hybrids) often show hybrid vigour (heterosis) — superior to either parent. Used in: developing high-yield rice (IR8), wheat (Borlaug's Green Revolution varieties), maize hybrids.
Quick Revision
| Technology | Application |
|---|
| PCR | DNA amplification, COVID testing, forensics |
| Genetic engineering | Insulin production, GM crops |
| Bt cotton | Pest resistance (bollworm) |
| DNA fingerprinting | Forensics, paternity testing |
| Cloning | Dolly the sheep (1996) |
| Bioremediation | Clean up pollution |
| Tissue culture | Plant propagation |
| Restriction enzymes | Cut DNA at specific sites |
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