The Light-Independent Stage

Question 1

What are 3 examples of complex organic molecules produced during the calvin cycle?

Answer 1

• Starch (storage)
• Sucrose (translocation)
• Cellulose (cell wall)

Question 2

What are the 3 main steps in the Calvin Cycle?

Answer 2

CO2 is fixated by combining it with Ribulose Bisphosphate (5C compound), catalysed by rubisco, yielding 2 molecules of glycerate 3-phosphate (GP, a 3C compound)
.
GP is reduced to TP (triose phosphate) involving NADP and ATP
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Ribulose Bisphosphate regenerated from TP using ATP

Question 3

What is carbon fixation

Answer 3

• CO2 combines with 5C sugar Ribulose Bisphosphate
• Catalysed by Rubisco enzyme
• Produces 6C compound which is unstable
• Splits into 2 glycerate 3-phosphate (GP) molecules
• CO2 has been ‘fixed’

Question 4

How does the reduction of GP work?

Answer 4

• Energy from ATP, and hydrogen from NADPH (both from light dependent stage)
• Are used to reduce GP tp TP (3C compound as well)

Question 5

How does the regeneration of ribulose bisphosphate work?

Answer 5

• 1/6th of TP used to produce useful organic molecules for the plant
• 5/6 used to regenerate Ribulose Bisphosphate
• Requires ATP