Question
NEET 2022 (paraphrased): Regarding photosynthesis, which of the following statements is correct? (a) light reactions refers to Calvin cycle in stroma; fix CO₂ into sugars (b) dark reactions is characterised by occur in thylakoid; produce ATP, NADPH, O₂ (c) RuBisCO — most abundant enzyme on Earth; fixes CO₂ (d) Z-scheme has no role in photosynthesis
Solution — Step by Step
This option swaps the definitions. light reactions is actually occur in thylakoid; produce ATP, NADPH, O₂, not what (a) claims. So (a) is out.
Similarly, dark reactions means Calvin cycle in stroma; fix CO₂ into sugars. Option (b) is mismatched. Out.
This one reads correctly: RuBisCO — most abundant enzyme on Earth; fixes CO₂. Match with NCERT wording confirms it.
Z-scheme — electron path PS II → PS I → NADP⁺ — plays a real role in photosynthesis, so option (d) is factually wrong.
Correct answer: (c) RuBisCO — most abundant enzyme on Earth; fixes CO₂.
Why This Works
NEET PYQs on photosynthesis rely on definition swapping. The examiner takes two correct facts and pairs them with the wrong terms. If you know each fact cold, the MCQ dissolves in 20 seconds.
Alternative Method
For definition-swap MCQs, don’t read all four options first. Read option (a), decide true/false, then (b), and so on. This prevents confusion between similar-looking options.
NEET reuses the same fact set every 2–3 years with different distractors. Master the four NCERT facts on photosynthesis listed here and you’ll handle almost any MCQ on this chapter.
Common Mistake
Students second-guess themselves when they see a familiar option listed as “wrong” in the stem. Trust the elimination — if you know the definition, stick with it.
Keep a one-page sheet of definitions for every NEET chapter. Revise only that sheet in the last 48 hours before the exam.