11.3 light-independent reactions

Question 1

what cycle describes the light-independent reaction?

Answer 1

the calvin cycle

Question 2

what does the light-independent reaction depend on?

Answer 2

• reduced NADP
• ATP (also comes from respiration)

Question 3

how does the calvin cycle work? (4)

Answer 3

1) CO2 reacts with RuBP (catalysed by rubisco) forms 2* GP
2) reduced NADP reduces GP -> triose phospate (TP) using energy from ATP
3) 1TP used to generate organic molecules: glucose, amino acids
4) 5TP used to regenerate RuBP

Question 4

what is the compensation point of photosynthesis?

Answer 4

level of light intensity at which rate of O2 produced = rate of O2 utilisation

Question 5

where is the site of light-independent reaction?

Answer 5

stroma

Question 6

what are the adaptations of light-independent reactions?

Answer 6

• enzymes needed are in stromal fluid
• membrane-bound: chemical environment is seperated from cytoplasm
• grana is surrounded by stroma - products of light-dependent reactions diffuse readily
• dna & ribosomes in stroma can readily manufacture proteins needed for reactions