4.3 - Light-Independent reaction

Question 1

What products are carried over from the LDR?

Answer 1

ATP and Reduced NADP.

Question 2

Does this stage actually require light?

Answer 2

No.

Question 3

Where does this reaction take place?

Answer 3

In the stroma of the chloroplasts.

Question 4

How does CO2 enter the cycle?

Answer 4

Diffuses into the leaf through stomata. Dissolves in water around walls of mesophyll cells. Diffuses through plasma membrane, cytoplasm, chloroplast membranes - into stroma of chloroplast.

Question 5

What does the CO2 combine with? Also, what does this reaction form?

Answer 5

Combines with RuBP (5-carbon) - vía an enzyme.

It forms 2 molecules of GP (3-carbon).

Question 6

How is Glycerate-3-Phosphate reduced, and what to?

Answer 6

It’s reduced by ATP and Reduced NADP from the LDR (forming ADP + Pi and NADP respectively). This forms Triose Phosphate.

Question 7

What happens to the Reduced NADP after it’s been oxidised?

Answer 7

It returns to the LDR, to accept more Hydrogen.

Question 8

What happens to TP?

Answer 8

Some is converted to useful organic substances (e.g. glucose). Most regenerate RuBP using ATP from LDR.

Question 9

Why is the fluid of the stroma beneficial?

Answer 9

It contains the enzymes required for LIR. It also surrounds the grana, so products of the LDR can easily diffuse into stroma.

Question 10

What does the chloroplast contain that benefits the LIR?

Answer 10

DNA and Ribosomes so some proteins needed for the LIR can be quickly manufactured.