UPSC CSE IAS · UPSC General Studies & Ethics
General Science & Technology
Covers general science across physics, chemistry, biology and recent science and technology developments.
Eight concepts for science and technology: DNA tools and vaccines, blood groups, ISRO missions and L1, the EM spectrum, fission versus fusion, frontier tech for GS-III, and India's nuclear doctrine. Tables and pegs carry the examinable pairings; almost nothing here is a computation.
- UPSC CSE IAS
- Medium level
- 8 concepts
- 6 practice questions
1DNA tools: PCR, CRISPR, sequencing
DNA carries genetic information. Three jobs look similar in a headline and are easy to swap: amplifying a fragment, editing a sequence, and reading a sequence.
PCR amplifies DNA — it makes many copies of a chosen stretch. CRISPR-Cas9 edits DNA — a guide RNA directs Cas9 to cut at a specific site so genes can be added, deleted or modified. Sequencing reads the order of bases; it does not by itself amplify or rewrite them.
Figure. Three DNA jobs Prelims swaps: PCR amplifies a fragment, CRISPR edits a sequence, sequencing reads the order — same molecule, different verbs.
| Tool | Job | Common confusion |
|---|---|---|
| PCR | Amplifies a chosen DNA stretch | Does not sequence or edit |
| CRISPR-Cas9 | Edits DNA at a guided cut site | Not mere amplification |
| Sequencing | Reads the order of bases | Does not rewrite the gene |
A lab needs many copies of one gene fragment before further work, but must not change the sequence itself. Which tool matches that job?
- CRISPR-Cas9, because Cas9 cuts and then copies the gene
- PCR, because it amplifies a chosen stretch without rewriting it
- Whole-genome sequencing, because reading bases creates more DNA
PCR amplifies. CRISPR edits (cuts/modifies). Sequencing reads bases — it does not manufacture copies as its primary job.
2Vaccine platforms
Vaccines work by priming immunity so the body recognises a pathogen before a real infection. Platform type is the load-bearing peg: what is delivered, and what the immune system is trained against.
mRNA vaccines (Pfizer/Moderna against COVID-19) deliver instructions to make the spike protein. India's Covaxin was an inactivated-virus vaccine. Covishield is a viral-vector vaccine. Other textbook classes include live-attenuated and subunit vaccines.
Figure. Vaccine platforms classified by what is delivered: live attenuated, inactivated or subunit, viral vector, and nucleic-acid (mRNA/DNA).
| Platform | What is delivered | Named example |
|---|---|---|
| Inactivated | Killed whole virus | Covaxin |
| Viral vector | Harmless carrier virus with pathogen gene | Covishield |
| mRNA | Instructions to make antigen (e.g. spike) | Pfizer / Moderna |
| Live-attenuated | Weakened live pathogen | Classic textbook class |
| Subunit | Purified antigen pieces | Classic textbook class |
A claim pairs Covaxin with mRNA and Covishield with inactivated virus. What is the correct pairing?
- Covaxin = inactivated; Covishield = viral vector; Pfizer/Moderna = mRNA
- Covaxin = mRNA; Covishield = inactivated; Pfizer/Moderna = viral vector
- Covaxin = viral vector; Covishield = mRNA; Pfizer/Moderna = inactivated
Covaxin is inactivated, Covishield is viral vector, and Pfizer/Moderna are mRNA. The other options swap those platforms.
3ABO and Rh blood groups
The ABO system classifies blood by antigens on red cells. In transfusion logic under standard teaching, group O is the universal donor and group AB is the universal recipient. The Rh factor adds the +/− typing used with ABO.
Figure. ABO transfusion pegs: O as universal donor, AB as universal recipient; A/B name antigens; Rh is the separate plus/minus factor.
| Group | Transfusion peg |
|---|---|
| O | Universal donor (standard ABO teaching) |
| AB | Universal recipient (standard ABO teaching) |
| A / B | Compatible within own antigen rules |
| Rh factor | Determines +/− typing alongside ABO |
In an emergency with no cross-match detail beyond ABO teaching pegs, which statement matches the standard universal-donor / universal-recipient rule?
- AB is the universal donor; O is the universal recipient
- O is the universal donor; AB is the universal recipient
- Rh-positive blood is always the universal donor regardless of ABO
Standard ABO peg: O donates universally; AB receives universally. The first option reverses it; Rh does not replace ABO for that peg.
4ISRO missions and Lagrange L1
ISRO mission items almost always swap target bodies. Chandrayaan-3 (2023) achieved the first soft landing near the lunar south pole. Mangalyaan (Mars Orbiter Mission, 2014) was India's Mars orbiter. Gaganyaan is the upcoming human spaceflight programme. PSLV and GSLV/LVM3 are the main launch vehicles.
Aditya-L1 observes the Sun from the Sun–Earth Lagrange point L1 — about 1.5 million km from Earth toward the Sun — for uninterrupted solar viewing. It is not in lunar orbit.
Figure. Mission–target pairs: Chandrayaan-3 to the Moon, Mangalyaan to Mars, Aditya-L1 to the Sun at Lagrange L1 — swap targets and the stem fails.
| Mission | Target / peg | Year / note |
|---|---|---|
| Chandrayaan-3 | Moon (soft landing near south pole) | 2023 |
| Aditya-L1 | Sun (Sun–Earth L1) | ~1.5 million km toward the Sun |
| Mangalyaan (MOM) | Mars orbiter | 2014 |
| Gaganyaan | Human spaceflight | Upcoming |
| PSLV / GSLV–LVM3 | Launch vehicles | Workhorse / heavy lift |
Consider the following: (1) Chandrayaan-3 achieved a soft landing near the lunar south pole. (2) Aditya-L1 is placed in orbit around the Moon. (3) Mangalyaan was India's mission to Mars. Which statements are correct?
- 1 and 2 only
- 2 and 3 only
- 1 and 3 only
- 1, 2 and 3
(1) and (3) match the source. (2) is false — Aditya-L1 studies the Sun from Sun–Earth L1, not the Moon.
5Electromagnetic spectrum order
The electromagnetic spectrum is an ordered ladder of increasing frequency (and energy): Radio, Microwave, Infrared, Visible, Ultraviolet, X-ray, Gamma. A common mnemonic for low-to-high energy is "Raging Martians Invaded Venus Using X-ray Guns".
Semiconductors and superconductivity sit beside this ladder as technology underpinnings in the same general-science note; the examinable order itself is the spectrum sequence.
Figure. Electromagnetic spectrum in increasing frequency and energy: Radio → Microwave → Infrared → Visible → Ultraviolet → X-ray → Gamma. Equal band widths are schematic order, not proportional wavelength.
| Band | Relative place |
|---|---|
| Radio | Lowest frequency in this list |
| Microwave | Above radio |
| Infrared | Above microwave |
| Visible | Above infrared |
| Ultraviolet | Above visible |
| X-ray | Above ultraviolet |
| Gamma | Highest frequency in this list |
Which ordering of electromagnetic bands is correctly increasing in frequency?
- Gamma < X-ray < Ultraviolet < Visible
- Radio < Microwave < Infrared < Visible < Ultraviolet < X-ray < Gamma
- Infrared < Microwave < Radio < Visible
Increasing frequency order is Radio, Microwave, Infrared, Visible, UV, X-ray, Gamma. The other options reverse or scramble neighbouring bands.
6Nuclear fission and fusion
Nuclear fission splits heavy nuclei such as uranium or plutonium and releases energy — the process that powers reactors. Nuclear fusion combines light nuclei such as hydrogen and is the process that powers the Sun; projects such as ITER aim at controlled fusion, which remains experimental for power generation.
Figure. Fission splits heavy nuclei (reactors); fusion joins light nuclei (stars, research devices) — opposite processes, easy to swap in a stem.
| Process | What happens | Key point |
|---|---|---|
| Fission | Heavy nucleus splits | Powers reactors (U / Pu) |
| Fusion | Light nuclei combine | Powers the Sun; ITER experimental |
Which statement correctly pairs the nuclear process with its role?
- Fusion splits uranium in commercial reactors; fission powers the Sun
- Fission splits heavy nuclei in reactors; fusion combines light nuclei (as in the Sun) and remains experimental in projects such as ITER
- Both fission and fusion are commercial baseload sources worldwide via ITER today
Fission splits heavy nuclei in reactors; fusion combines light nuclei and is the Sun's process, with ITER still experimental. The first option swaps them; the third overclaims commercial fusion.
7Emerging technologies for GS-III
Frontier science and technology items in GS-III are less about deriving a formula and more about knowing what the technology is for and that governance and ethics travel with it.
Artificial intelligence and machine learning, quantum computing (including India's National Quantum Mission), 5G, blockchain, and nanotechnology are the named frontier areas in this topic's source note.
Figure. GS-III emerging-tech items cluster into AI/ML, quantum, biotech and space/telecom — know the job of each family, not a formula derivation.
| Area | GS-III note |
|---|---|
| AI / machine learning | Automation and decision systems; ethics and governance |
| Quantum computing | National Quantum Mission among Indian pegs |
| 5G | Next-generation mobile connectivity |
| Blockchain | Distributed ledger applications; governance angles |
| Nanotechnology | Engineering at the nanoscale; dual-use and safety angles |
Which Indian mission peg belongs with quantum computing in the frontier-technology list?
- National Quantum Mission
- Gaganyaan alone, because human spaceflight is quantum-based
- Covaxin platform trials, because mRNA is a quantum vaccine
The National Quantum Mission is the quantum-computing peg. Gaganyaan is human spaceflight; Covaxin is an inactivated vaccine — neither is the quantum peg.
8Nuclear doctrine and the triad
India follows a No First Use nuclear doctrine with credible minimum deterrence. Second-strike capability is organised as a nuclear triad: land-based Agni missiles, air delivery, and a sea leg via INS Arihant. DRDO develops indigenous defence systems.
Figure. India's No First Use / credible minimum deterrence rests on a triad: land-based missiles, air delivery and sea-based SSBN second strike.
Why the triad supports NFU
- PledgeNo First Use commits India not to initiate nuclear use; deterrence must still discourage an adversary's first strike.
- SurviveCredible minimum deterrence needs forces that can survive a first strike — hence multiple legs, not a single vulnerable silo.
- RespondLand (Agni), air, and sea (INS Arihant) together underwrite second-strike capability after a first strike.
| Element | Peg |
|---|---|
| Doctrine | No First Use; credible minimum deterrence |
| Land leg | Agni missiles |
| Air leg | Air-delivered nuclear capability |
| Sea leg | INS Arihant (SSBN) |
| R&D peg | DRDO indigenous systems |
Which statement correctly reflects India's nuclear posture?
- First-use doctrine with maximum arsenal expansion as the sole peg
- No First Use with credible minimum deterrence, backed by a triad including land Agni missiles, air delivery, and sea-based INS Arihant
- No nuclear triad; deterrence rests only on imported missiles with no DRDO role
No First Use and credible minimum deterrence, with a triad (Agni / air / Arihant), and DRDO as the indigenous-systems peg. The other options invent first-use or erase the triad.
Notes
- Biotechnology and health: DNA carries genetic information; PCR amplifies DNA; CRISPR-Cas9 enables gene editing. Vaccines work by priming immunity - mRNA vaccines (used against COVID-19) deliver instructions to make the spike protein; India's Covaxin was an inactivated-virus vaccine.
- Space technology: ISRO milestones include Chandrayaan-3 (2023, first soft landing near the lunar south pole), Aditya-L1 (solar observation at Lagrange point L1), Mangalyaan (2014 Mars orbiter) and the upcoming Gaganyaan human spaceflight. PSLV and GSLV/LVM3 are the main launch vehicles.
- Physics fundamentals for prelims: Newton's laws, work-energy, electromagnetic spectrum (radio to gamma), semiconductors and superconductivity underpin technology; nuclear fission powers reactors while fusion (as in ITER) remains experimental.
- Emerging technologies: Artificial Intelligence and machine learning, quantum computing (National Quantum Mission), 5G, blockchain, and nanotechnology are frontier areas with governance and ethical dimensions relevant to GS-III.
- Defence and nuclear: India follows a 'No First Use' nuclear doctrine with credible minimum deterrence; the nuclear triad (land Agni missiles, air, and sea via INS Arihant) provides second-strike capability. DRDO develops indigenous systems.
Formulas
- Electromagnetic spectrum order (increasing frequency): Radio < Microwave < Infrared < Visible < Ultraviolet < X-ray < Gamma.
- Lagrange points: L1 (Sun-Earth) is where Aditya-L1 is placed for uninterrupted solar observation, about 1.5 million km from Earth toward the Sun.
- Vaccine types: live-attenuated, inactivated (Covaxin), subunit, viral-vector (Covishield) and mRNA (Pfizer/Moderna).
- Nuclear reactions: fission splits heavy nuclei (uranium/plutonium) releasing energy; fusion combines light nuclei (hydrogen) as in the Sun.
- Blood groups (ABO system): O is the universal donor and AB the universal recipient; Rh factor determines +/- typing.
Exam traps & shortcuts
- Vaccine-platform pairing for current affairs MCQs: Covaxin = inactivated, Covishield = viral vector, Pfizer/Moderna = mRNA.
- EM spectrum mnemonic (low to high energy): 'Raging Martians Invaded Venus Using X-ray Guns' = Radio, Microwave, Infrared, Visible, UV, X-ray, Gamma.
- ISRO mission recall: Chandrayaan-3 = Moon south pole (2023), Aditya-L1 = Sun (L1), Gaganyaan = human spaceflight.
- For science MCQs, eliminate options that violate conservation laws or misplace a technology's function (e.g., PCR does not sequence, it amplifies).
Reference tables
Reconstruct each line from its concept; use this only to check the wording.
| Item | Peg |
|---|---|
| PCR vs CRISPR | PCR amplifies; CRISPR edits; sequencing reads |
| Vaccine platforms | Covaxin = inactivated; Covishield = viral vector; Pfizer/Moderna = mRNA |
| ABO | O universal donor; AB universal recipient; Rh = +/− |
| Chandrayaan-3 | 2023 Moon south-pole soft landing |
| Aditya-L1 | Sun from Sun–Earth L1 (~1.5 million km sunward) |
| Mangalyaan | 2014 Mars orbiter |
| EM spectrum | Radio → Microwave → IR → Visible → UV → X-ray → Gamma |
| Fission / fusion | Fission splits heavy (reactors); fusion combines light (Sun / ITER) |
| Nuclear doctrine | NFU + credible minimum deterrence; triad Agni / air / Arihant |
Recap
Read only this the night before.
- DNA jobs
- PCR amplifies; CRISPR-Cas9 edits; sequencing reads.
- Vaccines
- Covaxin = inactivated; Covishield = viral vector; Pfizer/Moderna = mRNA.
- Blood
- O universal donor; AB universal recipient; Rh adds +/−.
- ISRO
- Chandrayaan-3 = Moon south pole (2023); Aditya-L1 = Sun at L1; Mangalyaan = Mars (2014); Gaganyaan = human spaceflight.
- L1
- Sun–Earth L1 ~1.5 million km from Earth toward the Sun.
- EM spectrum
- Radio < Microwave < IR < Visible < UV < X-ray < Gamma (mnemonic: Raging Martians…).
- Fission / fusion
- Fission splits heavy nuclei (reactors); fusion combines light nuclei (Sun; ITER experimental).
- Doctrine
- No First Use; credible minimum deterrence; triad = Agni + air + INS Arihant.
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