NEET Previous Year Question Focus Areas

Most Tested Topic 1 — PS I vs PS II Distinction Nearly every NEET paper includes a question on this distinction. Key facts:

• PS II = P680 = 680 nm = splits water = evolves $O_{2}$ = Hill reaction = acts first
• PS I = P700 = 700 nm = reduces NA$DP^{+}$ → NADPH = acts second
• Both are forms of Chl a
• Trap: "PS I acts first because it is numbered first" — WRONG

Most Tested Topic 2 — Cyclic vs. Non-cyclic Products Standard question: "Products of cyclic photophosphorylation?" Answer = ATP only. Distractors always include NADPH and $O_{2}$ as options. Must know: cyclic = PS I only = no PS II = no photolysis = no $O_{2}$, no NADPH. Location: cyclic = stroma lamellae; non-cyclic = grana.

Most Tested Topic 3 — C3/C4/CAM First Products C3: First stable product = 3-PGA (3C); acceptor = RuBP (5C); enzyme = RuBisCO. C4: First stable product = OAA (4C); acceptor = PEP (3C); enzyme = PEP carboxylase in mesophyll. CAM: Same as C4 biochemically but temporal separation; malic acid stored at night.

Most Tested Topic 4 — Calvin Cycle Stoichiometry ATP for 1 glucose = 18 (not 12). NADPH = 12. NEET uses "12 ATP + 12 NADPH" as a very common wrong option.

Most Tested Topic 5 — C4 Anatomy Kranz anatomy = only in C4 plants (not C3, not CAM). Bundle sheath = Calvin cycle. Mesophyll = initial fixation. Examples of C4: maize, sugarcane, sorghum.

Emerging Topic for 2026 — Multi-Step Application Recent NEET trends show increasing use of: limiting factor graph interpretation, assertion-reason on photophosphorylation, and application questions connecting photorespiration to crop yield. Prepare for scenario-based questions.