The Light Independent stage or The Calvin cycle

Question 1

what is the Calvin cycle

Answer 1

• also known as the light independent stage
• does not need light energy but does require the products from the light dependent stage (ATP and NADPH)
• makes organic compounds such as starch, glucose, cellulose

Question 2

what is carbon fixation?

Answer 2

-carbon dioxide combines with a 5C sugar known as ribulose bisphosphate (RuBP)
- the enzyme rubisco (ribulose bisphosphate carboxylase) cataylses this reaction
- this forms a 6C compound which is unstable so splits into 2
- gives 2 molecules of 3C compound called glycerate 3- phosphate
- carbon dioxide has been fixed as it is now a part of the plant cell

Question 3

explain the reduction of GP

Answer 3

• using hydrogen ions from NADPH and energy from ATP GP is reduced to triose phosphate (TP)
• one carbon is removed to produce organic molecules such as glucose, starch, cellulose

Question 4

what is the regeneration of ribulose bisphosphate

Answer 4

5 out of every 6 molecules of TP are recycled by phosphorylation using ATP from the light dependent stage to three molecules of RuBP