Transport in Plants & Mineral Nutrition — NEET Exam Strategy — Summary

Highest-yield topic in this session: Nitrogen cycle bacteria. Questions appear every 1–2 years. Memorise the exact sequence: Nitrosomonas → $NO_{2}^{-}$ → Nitrobacter → $NO_{3}^{-}$ . Denitrifiers are Pseudomonas and Thiobacillus — not Nitrobacter.
Second highest-yield: Casparian strip. Expect direct questions: "Casparian strip is found in ___" (Answer: endodermis). "Made of ___" (Answer: suberin). "Its function ___" (Answer: forces apoplast water into symplast for selective ion uptake).
Guttation vs transpiration trap: This distinction appears in MCQs at least once every two years. Guttation = root pressure = liquid = hydathodes = night. Transpiration = cohesion-tension = vapour = stomata = day.
Deficiency symptom approach: When given a symptom, determine the element using two steps: (1) Is it chlorosis (lack of green) or necrosis (cell death)? Chlorosis: N, K, Mg, Fe, Mn, Zn, Mo, S. Necrosis: Ca, Mg, Cu, K. (2) Old or young leaf? Old = mobile element deficiency; Young = immobile element deficiency.
Nitrogenase requirements: If a question asks about conditions for nitrogen fixation, remember the four requirements: Mo-Fe protein cofactor, 16 ATP energy, 8 electrons, and strictly anaerobic environment. Leghemoglobin provides the anaerobic environment in nodules.
Water potential calculation: If a question gives Ψs = −10 bar and Ψp = +4 bar, then Ψw = −6 bar. Water moves from the region with higher (less negative) Ψw to the region with lower (more negative) Ψw.
Do not waste time on: Exact concentrations of micronutrients (micromolar vs millimolar), specific enzyme names for each element's function (except Mo for nitrogenase/nitrate reductase, Mn for PS II photolysis, Cu for plastocyanin).
Fast recall triggers: "Pink pigment in nodules" → leghemoglobin. "Heterocysts" → Anabaena/Nostoc. "Whiptail" → Mo deficiency. "Internal cork" → B deficiency.