Previous-year question practice database
Answer
Exam answer
NICOTINAMIDE ADENINE DINUCLEOTIDE PHOSPHATE.
Explanation
Write every word out; abbreviations earn nothing.
WHAT IT DOES: NADP is the hydrogen ACCEPTOR of the light reaction. When water is split during photolysis, the hydrogen released is picked up by NADP to form NADPH₂, which then carries that hydrogen into the dark reaction to reduce carbon dioxide into glucose.
Think of it as a carrier rather than a chemical to be memorised — it ferries hydrogen from the light reaction to the dark reaction, which is why the two reactions are linked at all.
Spelling is where marks go here. Note NICOTINAMIDE (not "nicotinamine") and DINUCLEOTIDE (not "dinucleotide phosphate" run together wrongly).
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