5.2.5 - Light-independent reactions

Question 1

Describe The LIR (Calvin Cycle)
(3 Points)

Answer 1

~ Doesn’t use light energy directly.

~ Takes place in the stroma of the chloroplasts.

~ The ATP and Reduced NADP from the LDR, supply the energy and hydrogen to make glucose from CO2.

Question 2

What Does The LIR (Calvin Cycle) Make?
(3 Points)

Answer 2

~ CO2 is combined with RuBP (5C), to make 2 molecules of GP (3C).

~ GP is reduced to GALP (3C), in a reaction involving Reduced NADP and ATP.

~ RuBP is regenerated from GALP, in reactions that use ATP.

Question 3

Describe The Process Of LIR (Calvin Cycle)
(7 Points)

Answer 3

1) CO2 combines with RuBP (5C), catalysed by the enzyme RUBISCO.

2) Resulting in an unstable (6C) splitting into 2, into 2 molecules of GP (3C).

3) The CO2 has been fixed, meaning it has been removed from the external environment and become part of a molecule inside the plant.

4) The hydrolysis of ATP provides energy to turn GP (3C), into GALP (3C).

5) This reaction also requires H+ ions from Reduced NADP, Reduced NADP is then recycled into NADP.

6) Some of the GALP is converted into useful organic compounds (Glucose), and some continues in the cycle to regenerate RuBP.

7) Five / Sixths of the GALP molecules are used to regenerate RuBP, using the rest of the ATP produced by the LDR

Question 4

What Other Organic Substances Can Be Made From The Products Of The LIR (Calvin Cycle)?
(4 Points)

Answer 4

~ Carbohydrates.

~ Lipids.

~ Amino acids.

~ Nucleic acids.