UPHESC Assistant Professor Agricultural Botany PYQs

Concept: India's NPK use is skewed towards N; the recommended ratio is 4 : 2 : 1.

1. In recent years the all-India ratio has hovered around 6–7 : 2.4–3 : 1 (e.g. about 6.7 : 2.4 : 1).
2. Ratios of 9 : 3 : 1 or 9 : 5 : 1 are not reported all-India figures (Punjab-type extremes are higher still in N).
3. The wide ratio reflects subsidised urea and costlier P and K.

Short trick: Ideal 4 : 2 : 1, actual ≈ 6.7 : 2.4 : 1.

Concept: Phloem-mobile nutrients (N, P, K, Mg) are remobilised from old to young leaves, so their deficiency shows first on older leaves.

1. Immobile: Ca, B (deficiency on young leaves/growing points).
2. S, Fe, Zn, Cu, Mn – low/intermediate mobility, symptoms on young leaves.

Short trick: Old leaves yellow first → mobile (N, P, K, Mg).

Concept: Microbes need about 24 : 1 C : N in their food; residues near or below this decompose quickly with net N release, while wide C : N residues decompose slowly and immobilise N.

1. Statement 1 is wrong: residues of 24–30 : 1 are close to the microbial optimum and decompose readily (net mineralisation begins below ~25–30 : 1).
2. Statement 2 is wrong: residues with 80 : 1 (e.g. straw) decompose slowly; microbes lock up soil N (immobilisation), causing temporary N deficiency.
3. Hence neither statement is correct.

Short trick: Narrow C : N = fast + release; wide C : N = slow + lock-up.

Concept: N. V. Kanitkar's ICAR monograph 'Dry Farming in India' (1944) first published the concept and practices of dry farming for Indian conditions.

1. Research began at Bombay-Deccan centres (Sholapur, Bijapur) in the 1930s.
2. Kanitkar is regarded as a pioneer of Indian dry-land agriculture.

Short trick: Kanitkar – 'Dry Farming in India' – 1944.

Concept: Water is a polar molecule (partial − on O, partial + on H) with high dielectric constant, so it hydrates ions and polar molecules – the 'universal solvent'.

1. Cohesion/adhesion and tensile strength explain ascent of sap.
2. High specific heat (thermal property) buffers temperature.

Short trick: Polar dissolves polar: 'like dissolves like'.

Concept: PCR amplifies a specific DNA segment in vitro, so it is a detection/diagnostic tool.

1. 1 ✔ – pathogen-specific primers detect viruses, bacteria, fungi, phytoplasma.
2. 3 ✔ – allele-specific PCR/sequencing diagnoses mutations.
3. 2 ✘ – monoclonal antibodies come from hybridoma technology (Köhler & Milstein).
4. 4 ✘ – rDNA is introduced by transformation (Agrobacterium, gene gun), not PCR.

Short trick: PCR copies and detects – it neither makes antibodies nor transforms cells.

Concept: Oligomycin blocks the F_o proton channel of ATP synthase – it is an inhibitor of phosphorylation, not an uncoupler.

1. Uncouplers dissipate the proton gradient: DNP, FCCP, CCCP.
2. Valinomycin, a K⁺ ionophore, collapses the membrane potential and acts as an uncoupler-type agent.
3. With oligomycin both ATP synthesis and electron flow stop; with uncouplers electron flow continues.

Short trick: Oligomycin – 'O' for F_O blocker.

Concept: Catalytic efficiency (specificity constant) = $k_{cat}/K_m$, units M⁻¹ s⁻¹.

1. $K_m$ – substrate concentration at half $V_{max}$ (affinity).
2. $k_{cat}$ – turnover number.
3. Upper limit of $k_{cat}/K_m$ ≈ 10⁸–10⁹ M⁻¹s⁻¹ (diffusion-limited, 'perfect' enzymes like catalase).

Short trick: Efficiency = speed ÷ Km: fast and high-affinity.

Concept: In Agrobacterium-mediated transformation the gene must be cloned first, then carried by the bacterium into plant cells.

1. Step 2: gene inserted into the (binary/Ti) plasmid with restriction enzyme and ligase.
2. Step 3: this plasmid is put into A. tumefaciens, which now carries the gene of interest.
3. Step 1: the bacterium is co-cultivated with plant cells/explants in culture (introduction).
4. Step 4: transformed cells are selected and regenerated into plants.
5. Correct order 2 → 3 → 1 → 4 is not among the codes; (B) puts 3 before 2 (the bacterium cannot carry the gene before it is cloned) and (C) puts 1 before 3. So no option is correct as printed.

Short trick: Clone → Carry → Co-cultivate → Regenerate (2-3-1-4).

Concept: Plant-specific RNA Pol IV and Pol V make non-coding RNAs for siRNA production and RNA-directed DNA methylation (RdDM), not snRNA.

1. Pol I – 28S/18S/5.8S rRNA.
2. Pol II – mRNA, most snRNAs, miRNA precursors.
3. Pol III – tRNA, 5S rRNA, U6 snRNA.
4. So pairing Pol IV/V with snRNA is wrong.

Short trick: Pol IV & V = plant silencing (siRNA, RdDM).

Concept: Restriction endonucleases ('molecular scissors') cut DNA at specific palindromic sites, making gene cloning possible.

1. e.g. EcoRI cuts G^AATTC giving sticky ends; DNA ligase then joins fragments.
2. DNase degrades DNA non-specifically; amylase and lipase digest starch and fats.

Short trick: Scissors = restriction enzyme; glue = ligase.

Concept: A plasmid (Lederberg, 1952) is a self-replicating extrachromosomal DNA (replicon) stably inherited without integration into the chromosome.

1. An episome (e.g. F factor) can exist free or integrate into the host chromosome.
2. A vector is any carrier DNA (plasmid, phage, cosmid) used for cloning.

Short trick: Plasmid = always outside; episome = in or out.

Concept: Energy flow is unidirectional: solar (light) energy → chemical energy in food (photosynthesis) → lost as heat through respiration at each trophic level.

1. Second law of thermodynamics: transformations degrade energy to heat.
2. Lindeman's 10% law – only ~10% passes to the next level.

Short trick: Sun → Sugar → Heat.

Concept: An ecotone is the transition zone (tension zone) between two communities, e.g. forest–grassland; it often has greater species richness (edge effect).

1. Ecocline – gradual gradient of communities along an environmental gradient.
2. Ecads – environmentally induced variants (phenotypic forms) of a species.
3. Ephemerals – short-lived plants completing life cycle in a brief favourable season.

Short trick: Eco-TONE = TENsion zone between two communities.

Concept: The Global Carbon Budget is produced by the Global Carbon Project – an international scientific consortium under Future Earth/WCRP – not the World Bank.

1. CCPI – Germanwatch with NewClimate Institute and CAN.
2. State of the Global Climate – WMO.
3. Emissions Gap Report – UNEP.

Short trick: World Bank publishes 'State and Trends of Carbon Pricing', not the Global Carbon Budget.

Concept: EIA notifications (1994, 2006) are issued under the Environment (Protection) Act, 1986.

1. Statement 1 correct.
2. Statement 2 wrong: Category A projects need clearance from the Central Government (MoEFCC, on EAC advice); Category B projects from the State-level SEIAA.

Short trick: A = All-India (Centre), B = state.

Concept: On 26 April 1986 reactor No. 4 of the Chernobyl nuclear power plant (then USSR, now Ukraine) exploded – the worst nuclear accident (INES level 7).

1. Fukushima (2011) is the other level-7 accident.
2. Bhopal (1984) – MIC gas leak.

Short trick: Chernobyl 1986 = nuclear; Bhopal 1984 = gas.

Concept: Smog = smoke + fog, a form of air pollution.

1. Classical (London, reducing) smog – SO₂, soot, fog in cold humid weather.
2. Photochemical (Los Angeles, oxidising) smog – NO_x + hydrocarbons + sunlight → O₃, PAN.

Short trick: Smoke + Fog = Smog.

Concept: LIDAR (Light Detection and Ranging), e.g. differential-absorption LIDAR (DIAL), sends laser pulses and analyses back-scattered light to map gas concentrations remotely over large areas.

1. Spectrophotometry, GC and mass spectrometry analyse samples collected at a point – they cannot map a whole town from one spot.

Short trick: LIDAR = laser radar – scans from one place.

Concept: Saffron (kesar) consists of dried stigmas with the upper part of the style of Crocus sativus (Iridaceae).

1. Colour – crocin; flavour – safranal; bitterness – picrocrocin.
2. Fennel – fruits; turmeric – rhizome; Rubia (manjistha) – root dye.

Short trick: Kesar = Crocus stigma (Pampore, Kashmir).