- UPSC Prelims asks several science and technology questions every year, and most are about applied science — biotechnology, nuclear energy and new technologies in the news — rather than textbook theory.
- The trick is to understand each technology well enough to judge statements: what CRISPR does, why India's nuclear programme needs fast breeder reactors, what a moderator is for.
- This page connects the basics to India's missions; for current details, see our notes on the IndiaAI Mission, National Quantum Mission and Semiconductor Mission.
Tools of Biotechnology
| Tool | Role |
|---|---|
| Restriction enzymes | Cut DNA at specific sequences — "molecular scissors" |
| DNA ligase | Joins DNA fragments — "molecular glue" |
| Plasmids | Small circular bacterial DNA used as vectors to carry genes |
| PCR (polymerase chain reaction) | Makes millions of copies of a DNA segment; invented by Kary Mullis |
| Gel electrophoresis | Separates DNA fragments by size |
The first recombinant DNA was made by Stanley Cohen and Herbert Boyer in the early 1970s. Human insulin made in bacteria (approved in 1982) was the first recombinant medicine.
Applications
- GM crops: Bt cotton (2002), carrying a gene from Bacillus thuringiensis that kills bollworms, is the only GM crop approved for commercial cultivation in India. Bt brinjal was put under a moratorium in 2010. GM mustard (DMH-11) received environmental-release approval in 2022, but the matter is before the Supreme Court. Approvals come from the Genetic Engineering Appraisal Committee (GEAC) under the Environment Ministry.
- Genome editing: CRISPR-Cas9 works like a programmable pair of scissors that edits a precise spot in DNA. Emmanuelle Charpentier and Jennifer Doudna won the 2020 Nobel Prize in Chemistry for it. In 2025, ICAR released India's first genome-edited rice varieties.
- DNA fingerprinting: developed by Alec Jeffreys (1984). In India, Lalji Singh of the CDFD, Hyderabad is called its father.
- Cloning: Dolly the sheep (1996) was the first mammal cloned from an adult cell.
- Stem cells can turn into many cell types; embryonic stem cells are the most versatile. They are used in research and in treatments such as bone-marrow transplants.
- Genome India Project: sequenced 10,000 genomes from across India to map the country's genetic diversity.
Molecular scissorsRestriction enzymes
Only GM crop (India)Bt cotton
GM approvalsGEAC
CRISPR Nobel2020
Three-stage planHomi Bhabha
PFBRKalpakkam, 500 MW
Fission and Fusion
| Nuclear fission | Nuclear fusion | |
|---|---|---|
| Process | A heavy nucleus (U-235, Pu-239) splits | Light nuclei (hydrogen isotopes) combine |
| Where | All nuclear power plants and atom bombs | The Sun and stars; hydrogen bombs |
| Status for power | Commercial | Experimental — ITER in France, of which India is a member |
Parts of a Nuclear Reactor
- Fuel — uranium or plutonium.
- Moderator — slows down neutrons so they can cause further fission: heavy water, graphite or ordinary water.
- Control rods — absorb neutrons to control the reaction: cadmium or boron.
- Coolant — carries away heat: water, heavy water or liquid sodium (in fast breeders).
India's Three-Stage Nuclear Programme
Designed by Homi J. Bhabha to use India's large thorium reserves (in monazite sands), since its uranium reserves are small.
| Stage | Reactor | Fuel |
|---|---|---|
| 1 | Pressurised Heavy Water Reactors (PHWRs) | Natural uranium; produces plutonium |
| 2 | Fast Breeder Reactors — the 500 MW PFBR at Kalpakkam (core loading began in 2024) | Plutonium; "breeds" more fuel than it uses and converts thorium into U-233 |
| 3 | Thorium-based reactors such as the Advanced Heavy Water Reactor | Thorium and U-233 |
- The Atomic Energy Commission was set up in 1948; BARC at Trombay began in 1954 and was renamed after Bhabha in 1967.
- Tarapur (1969) was India's first nuclear power plant; Kudankulam (Tamil Nadu, built with Russia) is the largest.
- Nuclear tests: Pokhran-I ("Smiling Buddha", 1974) and Pokhran-II ("Operation Shakti", 1998).
- The Budget for 2025–26 set a goal of 100 GW of nuclear power by 2047 and launched a Nuclear Energy Mission for small modular reactors (SMRs).
Emerging Technologies
| Technology | Basic idea | India's initiative |
|---|---|---|
| Artificial intelligence | Machines that learn from data to perform tasks such as recognising language and images | IndiaAI Mission (2024) |
| Quantum computing | Uses qubits, which can be in superposition and entangled, to solve some problems far faster than ordinary computers | National Quantum Mission (2023) |
| Semiconductors | Chips made mainly from silicon; the base of all electronics | India Semiconductor Mission (2021) |
| 5G | High speed, low delay, many connected devices | Launched October 1, 2022 |
| Blockchain | A shared, tamper-resistant digital ledger | Used in land records and supply chains |
| Green hydrogen | Hydrogen made by splitting water with renewable electricity | National Green Hydrogen Mission — 5 million tonnes a year by 2030 |
| Nanotechnology | Materials engineered at 1–100 nanometres; graphene is a one-atom-thick layer of carbon | Nano Mission (2007) |
- Statement questions on GM crops: which crop is approved, who approves (GEAC), what Bt means.
- Reactor logic: what the moderator, control rods and coolant do; why the second stage needs fast breeders.
- Emerging tech basics: qubits, CRISPR, graphene — usually framed as "Which of the following statements is correct?"
Q1. Which is the only genetically modified crop approved for commercial cultivation in India?
✅ Answer: (d) Bt cotton
💡 Explanation: Bt cotton was approved in 2002; Bt brinjal is under a moratorium and GM mustard is before the Supreme Court.
Q2. In a nuclear reactor, the moderator is used to:
✅ Answer: (b) Slow down neutrons
💡 Explanation: Moderators such as heavy water slow neutrons so they can sustain fission; control rods absorb neutrons.
Q3. Restriction enzymes are known as:
✅ Answer: (a) Molecular scissors
💡 Explanation: They cut DNA at specific sites; DNA ligase is the molecular glue.
Q4. The second stage of India's three-stage nuclear programme is based on:
✅ Answer: (c) Fast breeder reactors
💡 Explanation: Fast breeder reactors such as the PFBR at Kalpakkam use plutonium and breed new fuel.
Q5. The 2020 Nobel Prize in Chemistry was awarded for developing:
✅ Answer: (b) CRISPR-Cas9 genome editing
💡 Explanation: Emmanuelle Charpentier and Jennifer Doudna were honoured for CRISPR-Cas9.
🔁 Revise in 60 Seconds
- Restriction enzymes = scissors; ligase = glue; plasmid = vector; PCR = copying.
- Bt cotton only commercial GM crop (2002); GEAC approves; CRISPR Nobel 2020; Dolly 1996; Lalji Singh — DNA fingerprinting (India).
- Moderator slows neutrons (heavy water/graphite); control rods absorb (cadmium/boron).
- Three stages: PHWR → FBR (PFBR Kalpakkam) → thorium. Tarapur 1969 first; Kudankulam largest; 100 GW by 2047.
📌 Prelims Traps to Avoid
- ✘ Control rods absorb neutrons; the moderator only slows them.
- ✘ GM mustard has environmental clearance, but it is not in commercial cultivation.
- ✘ Fusion powers the Sun; all current nuclear power plants use fission.
What is India's three-stage nuclear programme?
A plan by Homi Bhabha to use India's thorium reserves. Stage one uses natural uranium in pressurised heavy water reactors, producing plutonium. Stage two uses that plutonium in fast breeder reactors such as the PFBR at Kalpakkam, which also convert thorium into uranium-233. Stage three uses thorium and U-233 in thorium-based reactors.
What is CRISPR-Cas9?
A genome-editing tool that uses a guide RNA to lead the Cas9 enzyme to a precise spot in DNA, where it makes a cut so a gene can be removed, repaired or changed. Its developers won the 2020 Nobel Prize in Chemistry.