NEET Biology · Plant Physiology Block
NEET Plant Physiology PYQ — 4-Chapter Block (2005–2025)
Plant Physiology is a 4-chapter block — Transport in Plants, Mineral Nutrition, Respiration in Plants, Plant Growth & Development — combined ~10% NEET Biology weightage on trend, often 3–4 questions per paper. Photosynthesis (the 5th plant chapter) is covered separately.
Plant Physiology PYQs spanning AIPMT 2005 to NEET 2025, covering water transport, mineral requirements, respiration metabolism and plant hormones. Every solution cites NCERT Class 11 references.
Plant Physiology (Transport, Mineral Nutrition, Respiration, Plant Growth) at a Glance
Key Sub-Topics & What's Tested
Transport in Plants
Water potential concept, imbibition, osmosis, plasmolysis, root absorption, transpiration (types), ascent of sap, phloem transport (mass flow hypothesis).
Mineral Nutrition
Essential elements (macro and micro), deficiency symptoms, nitrogen cycle, biological nitrogen fixation (symbiotic and free-living), hydroponics.
Respiration in Plants
Glycolysis, Krebs cycle, electron transport system, oxidative phosphorylation, fermentation, RQ (respiratory quotient) for various substrates.
Plant Growth & Development
Growth phases (formation, elongation, maturation), plant hormones (auxins, gibberellins, cytokinins, ABA, ethylene), photoperiodism, vernalisation.
Plant Hormones — Auxins
IAA, NAA, 2,4-D; apical dominance, phototropism, gravitropism, growth promotion, parthenocarpy, weedicide action of 2,4-D.
Plant Hormones — Gibberellins & Cytokinins
GA₃ in seed germination, bolting in cabbage, delay of senescence. Cytokinins: cell division, retardation of leaf senescence, root/shoot ratios.
Photoperiodism & Vernalisation
Short-day vs long-day vs day-neutral plants, role of phytochrome (Pr, Pfr), critical photoperiod, vernalisation in biennials.
Glycolysis & Respiration Pathway
10 steps of glycolysis, Krebs cycle, net ATP yield per glucose (~38 or 36), difference between aerobic and anaerobic respiration in plants.
Question Type Distribution
| Question Type | Share (approx) | Example Pattern |
|---|---|---|
| Water/Mineral Transport Mechanism | 20% | Identify process causing stomatal opening — role of guard cells and K⁺. |
| Essential Element / Deficiency | 15% | Which deficiency causes chlorosis in leaves? (Mg, Fe, N deficiency) |
| Respiration Pathway Steps | 20% | Which stage of respiration occurs in mitochondrial matrix? (Krebs cycle) |
| Plant Hormone Identification | 20% | Which hormone is responsible for apical dominance? (Auxin) |
| Photoperiodism / Phytochrome | 10% | Which form of phytochrome induces flowering in long-day plants? (Pfr) |
| Respiratory Quotient (RQ) | 15% | RQ of fat substrate is closest to: (around 0.7) |
How to Solve Plant Physiology (Transport, Mineral Nutrition, Respiration, Plant Growth) PYQs
- 1Master the water potential equation. Ψ_w = Ψ_s + Ψ_p (solute + pressure). Pure water: Ψ_w = 0. Adding solute decreases Ψ_s (negative). Key to understanding transport.
- 2Plant hormones: one signature action each. Auxin: apical dominance. Gibberellin: seed germination. Cytokinin: cell division. ABA: stress response. Ethylene: fruit ripening.
- 3Respiration: know ATP yields per stage. Glycolysis: 2 ATP net. Krebs: 2 ATP + 6 NADH + 2 FADH₂. ETS: ~32 ATP from NADH/FADH₂. Total: ~36-38 ATP per glucose.
- 4For photoperiodism, know day-length definitions. Short-day plant = flowers when day length < critical. Long-day = flowers when day length > critical. Day-neutral = unaffected. Phytochrome Pfr promotes LD flowering.
- 5Essential elements split: macro vs micro. Macro (9): C, H, O, N, P, K, Ca, Mg, S. Micro (8): Fe, Mn, Cu, Zn, Cl, B, Mo, Ni. Memorise both lists.
Common Mistakes That Cost Marks
- Confusing cohesion-tension theory with mass flow. Cohesion-tension = ascent of sap (xylem). Mass flow = phloem transport (sucrose). Different mechanisms, different tissues.
- Wrong net ATP in glycolysis. Glycolysis yields 4 ATP gross but consumes 2, so NET 2 ATP. Ignoring the consumption gives double the answer.
- Calling auxin a growth inhibitor. Auxin is a growth PROMOTER (at normal concentrations). At very high concentrations it inhibits — 2,4-D weedicide action. Context matters.
- Confusing phototropism and photoperiodism. Phototropism = directional growth toward light. Photoperiodism = flowering response to day length. Different phenomena.
- Forgetting that respiration happens in ALL living cells. Not just in mitochondria-rich cells. Plant roots, stems, flowers, fruits all respire. Root respiration matters for aeration.
Related NEET Practice
Frequently asked questions
How many Plant Physiology PYQs should I solve?
Target 80–100 PYQs across the 4-chapter block. Given ~10% combined weightage, consistent practice delivers strong mock returns.
Is NCERT Class 11 enough for Plant Physiology?
Yes — NCERT chapters 11 (Transport), 12 (Mineral Nutrition), 14 (Respiration), 15 (Plant Growth) cover the block completely. Read each 3+ times.
What's the most-tested Plant Physiology pattern?
Plant hormone function matching — 5–6 PYQs per 10-year window. Know the 5 hormone classes (auxins, gibberellins, cytokinins, ABA, ethylene) and their signature actions.
Do I need to memorise glycolysis steps?
Yes — 10 enzyme-catalysed steps of glycolysis, Krebs cycle intermediates, ETS components. NCERT diagrams are tested directly. Draw from memory is ideal.
Is Photosynthesis part of Plant Physiology?
Technically yes, but it's a huge chapter on its own. We cover it separately at /neet/biology/photosynthesis/pyq due to ~4% standalone weightage.
How important is vernalisation for NEET?
Important — comes up in 2–3 PYQs per 10-year window. Know: triggered by cold exposure, flowering acceleration in biennials (wheat, cabbage), role of gibberellins.
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