LIR/ Calvin Cycle

Question 2

When in the stroma, what do the H+ ions and electrons do?

Answer 2

react with the co-enzyme NADP to form reduced NADP (NADPH)

Question 3

What protein do H+ ions diffuse through?

Answer 3

ATP synthase

Question 4

What enzyme catalyses the LIR?

Answer 4

Rubisco

Question 5

Why is the LIR temperature sensitive?

Answer 5

because it requires enzymes

Question 6

What is used in the Calvin cycle?

Answer 6

reduced NADP, ATP, CO2

Question 7

What is the role of ATP in the Calvin cycle?

Answer 7

hydrolysed to release energy and phosphate ions needed in the formation of TP from GP

Question 8

What is required in order to form triose phosphate molecules?

Answer 8

ATP and a H from reduced NADP

Question 9

Give 2 examples of what the glucose can be used to make?

Answer 9

glycerol used to make lipids
combine with nitrates to form amino acids
stored as starch
used in cell walls as cellulose

Question 10

How many times does the Calvin cycle need to happen before a hexose sugar (e.g glucose can be made)?

Answer 10

6

Question 11

Why is ATP needed for the second time in the Calvin cycle?

Answer 11

to regenerate the RuBP by joining a TP molecule to the molecule that donated it’s carbon atom for use in making organic molecules

Question 12

How many Carbon atoms leave the 2 x TP molecules to be used in organic molecules?

Answer 12

1

Question 13

What is GP reduced to form?

Answer 13

triose phosphate

Question 14

What does the reaction between RuBP and CO2 form?

Answer 14

2 x glycerate 3-phosphate (GP) (3 carbon compound)

Question 15

What reaction does rubisco catalyse?

Answer 15

the reaction between CO2 and RuBP

Question 16

How many carbons are in RuBP/ribulose biphosphate?

Answer 16

5

Question 17

What is the role of the reduced NADP in the Calvin cycle?

Answer 17

donates H to reduce molecule GP

Question 18

Describe the LIR

Answer 18

• CO2 reacts with RuBP which is catalysed by rubisco
• Forms a 6 C unstable molecule which is broken down
• This forms 2 GP
• GP reduced to triose phosphate, using reduced NADP and energy from ATP
• 2 molecules of TP (per 12) go to make hexose
• 10 molecules of TP (per 12) form 6 molecules RuBP
• all RuBP regenerated

Question 19

Why won’t the LIR occur if the LDR doesn’t occur?

Answer 19

• no ATP
• no NADPH
  needed for LIR (converting GP to TP)

Question 20

Why will the rate of LIR decrease if rate of Rubisco decreases?

Answer 20

• no CO2 reacts with RuBP
• so no GP

Question 21

Where is Rubisco found in a cell?

Answer 21

• stroma of chloroplasts

Question 22

What is the role of NADPH in LIR?

Answer 22

provides H for reduction of GP to TP
(reduces GP)