5.8

Question 1

State the precise site of the LIR

Answer 1

Stroma (in the chloroplast)

Question 2

State the alternate name for the LIR

Answer 2

Calvin Cycle

Question 3

The light independent reactions can be divided into three interlinked reactions:
carbon fixation, reduction and phosphorylation
1. Describe what happens in carbon fixation
2. Describe what happens in reduction
3. Describe what happens in phosphorylation

Answer 3

1. RuBp + CO2, with the presence of Rubisco, forms GP
2. GP reacts with ATP (turns to ADP and Pi) and NADPH (turns to NADP) to form GALP
3. 2x GALP leave to form carbohydrates, the rest react again with ATP (turns to ADP and Pi) to form RuBP again

Question 4

Describe the process of the light independent stage (4/5 marks)

Answer 4

Carbon dioxide fixed with RuBP by the enzyme RUBISCO
2 molecules of GP formed
GP reduced into GALP, which requires ATP and 2H+ from NADPH
2 molecules of GALP used to produce hexose sugar/nucleotides/amino acids/lipids
10 molecules of GALP reduced back into RuBP, which requires ATP

Question 5

Describe how the products of the light independent stage can be used to produce cellulose cell walls

Question 6

Explain why the light independent stage relies on the light dependent stage occurring