Biotechnology & genetics

Answer: (c) 1 and 3 only

Bioremediation speeds up the natural breakdown of pollutants by microbes, and microbes can be genetically engineered for the job. But microbes break down organic compounds; metals such as cadmium and lead are elements that cannot be degraded, only changed in form or immobilised, so statement 2 overclaims.

• ✓ 1. It uses microorganisms that feed on or co-metabolise contaminants, boosting the same biodegradation that happens in nature by supplying nutrients, oxygen or other electron acceptors.
• ✗ 2. Bioremediation is described as degrading organic contaminants. Heavy metals cannot be broken down by microbes, so 'readily and completely treated' is wrong; at best microbes change their chemical form.
• ✓ 3. Biotechnology uses genetically modified microbes for bioremediation; in 1971 Ananda Mohan Chakrabarty developed a bacterium that could break down oil spills.

Remember · Bioremediation = microbes degrading organic pollutants (oil, solvents, pesticides); engineered microbes help. Heavy metals cannot be degraded, only transformed or immobilised.

📘 Read it in NCERT: Class 12 Biology, Ch 10 (practise this chapter) · Class 8 Curiosity, Ch 2 (practise this chapter)

Question and answer: UPSC's official GS Paper I (2017, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (d) 1, 2 and 3

All three uses are correct. Reading a crop's full DNA reveals markers for traits such as drought tolerance and disease resistance, cuts the years needed to breed a new variety, and shows how crops and their disease-causing organisms interact.

• ✓ 1. When 90 chickpea genomes were sequenced, the work gave millions of genetic markers that can be used to breed varieties with better drought tolerance and disease resistance.
• ✓ 2. Breeding a new chickpea variety normally takes 4–8 years; the scientists behind the chickpea genome said the sequence could cut this to half.
• ✓ 3. Sequencing crop and pathogen genomes lets researchers study plant–pathogen interactions and plant resistance at gene level.

Remember · Genome sequencing in crops: finds trait markers (drought, disease resistance), speeds up breeding (chickpea: 4–8 years cut to about half) and reveals host–pathogen interactions.

Question and answer: UPSC's official GS Paper I (2017, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (c) Reproductive cloning of animals

Somatic Cell Nuclear Transfer (SCNT) is the technique used for reproductive cloning of animals. The nucleus of an ordinary body (somatic) cell is placed into an egg cell whose own nucleus has been removed, and the egg develops into an animal genetically identical to the donor.

• ✓ (c) Dolly the sheep (1997), the most famous cloned animal, was made this way. In India, NDRI Karnal has used a hand-guided version of the method to clone buffalo calves.
• ✗ (a) Biolarvicides are biological agents used to kill mosquito larvae. They have no link with moving cell nuclei.
• ✗ (b) Biodegradable plastics are made from natural or microbial polymers through chemistry and fermentation, not by nuclear transfer.
• ✗ (d) SCNT copies the donor's genome, including any inherited fault; it does not make an organism disease-free.

Remember · SCNT = nucleus of a body cell put into an enucleated egg. It is the method of reproductive cloning, as with Dolly the sheep.

Question and answer: UPSC's official GS Paper I (2017, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error