[11.3] the light-independent reaction

Question 1

where does the LIDR take place?

Answer 1

in the stroma

Question 2

what products from the LDR are taken to the LIDR?

Answer 2

• ATP
• reduced NADP

Question 3

how does carbon dioxide enter the LIDR?

Answer 3

• CO₂ from atomosphere diffuses into leaf through stomata
• dissolves in water around walls of mesophyll cells
• diffuses throgh cell membrane, cytoplasm, and chloroplast membranes into the stroma of the chloroplast

Question 4

describe the calvin cycle

Answer 4

• CO₂ reacts with RuBP (5C)
• catalysed by enzyme rubisco
• forms unstable 6C molecule
• 6C molecule splits into 2 x G3P
• NADPH reduces G3P to TP using energy from ATP
• NADP is re-formed and goes back to LDR
• 2/12 TPs makes 1 molecule of glucose
• 10/12 TPs form RuMP
• RuMP -> RuBP (ATP from LDR -> ADP + Pi)

Question 5

how many cycles need to take place for 1 glucose to be produced?

Answer 5

6

Question 6

since there are 6 cycles, how many of each molecule are there in a calvin cycle?

Answer 6

• 6 RuBP (30C)
• 6 CO₂ (6C)
• 6 unstable carbon molecule
• 12 G3P
• 12 TP (2 for glucose, 10 for regeneration)
• 6 RuMP

Question 7

how is the chloroplast adapted to carry out the LIDR?

Answer 7

• fluid in stroma contains all the enzymes needed to carry out LIDR
• stromal fluid is membrane-bound in chloroplasat so chemical environment with high conc of enzymes and substrates can be maintained
• stromal fluid surrounds grana so products of LDR in grana can readily diffuse into stroma
• contains DNA and ribosomes so can quickly and easily manufacture some of the proteins involved in the LIDR