Error Analysis — Common NEET Mistakes in Photosynthesis — Notes | NoteTube

#	Wrong Belief (Error)	Correct Fact	Why Students Make This Error
1	PS I acts first (because it is numbered first)	PS II acts FIRST; PS I acts second. Numbering = discovery order	"I" comes before "II" in Roman numerals
2	Cyclic photophosphorylation produces ATP + NADPH	Cyclic produces ATP ONLY	Students assume all light reactions make NADPH
3	C3 plants have 3 carbons in the $CO_{2}$ acceptor (RuBP)	RuBP has 5 carbons; "C3" refers to the 3C PRODUCT (3-PGA)	Confusing acceptor carbon count with pathway name
4	Photosynthesis equation: 6 $CO_{2}$ + $6H_{2}O$ → glucose + $6O_{2}$	Correct: $12H_{2}O$ on reactant side	Simplified equation seen in early textbooks
5	$O_{2}$ comes from $CO_{2}$ during photosynthesis	$O_{2}$ comes from WATER (Van Niel; confirmed by ^{18}O labelling)	Intuitive ( $CO_{2}$ contains O) but wrong
6	C4 plants use RuBisCO in mesophyll cells	PEP carboxylase in mesophyll; RuBisCO in bundle sheath	Forgetting the two-cell system
7	Photorespiration produces ATP (like aerobic respiration)	Photorespiration produces NO ATP; it is wasteful	Name similarity to respiration
8	Calvin cycle requires 12 ATP + 12 NADPH	Calvin cycle requires 18 ATP + 12 NADPH	Confusing 2 ATP/turn with 3 ATP/turn
9	Stroma lamellae = grana	Stroma lamellae = unstacked inter-granal membranes; Grana = stacked discs	Terms sound similar
10	CAM plants are a type of C4 plants	CAM is a SEPARATE category — temporal separation; C4 = spatial	Both use PEP carboxylase; different separation strategies

PS numbering trap: Discovery ≠ Function. "PS II Discovered 2nd, Acts 1st"
Cyclic = one system = one product: "1 system (PS I) → 1 product (ATP)"
Calvin cycle cost: "18 comes from 12+6 (12 ATP for reduction + 6 ATP for regeneration)"