LIR/Calvin Cycle

Question 1

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

Answer 1

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

Question 2

What protein do H+ ions diffuse through?

Answer 2

ATP synthase

Question 3

What enzyme catalyses the LIR?

Answer 3

Rubisco

Question 4

Why is the LIR temperature sensitive?

Answer 4

because it requires enzymes

Question 5

What is used in the Calvin cycle?

Answer 5

reduced NADP, ATP, CO2

Question 6

What is the role of ATP in the Calvin cycle?

Answer 6

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

Question 7

What is required in order to form triose phosphate molecules?

Answer 7

ATP and a H from reduced NADP

Question 8

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

Answer 8

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

Question 9

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

Answer 9

6

Question 10

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

Answer 10

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 11

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

Answer 11

1

Question 12

What is GP reduced to form?

Answer 12

triose phosphate

Question 13

What does the reaction between RuBP and CO2 form?

Answer 13

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

Question 14

What reaction does rubisco catalyse?

Answer 14

the reaction between CO2 and RuBP

Question 15

How many carbons are in RuBP/ribulose biphosphate?

Answer 15

5

Question 16

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

Answer 16

donates H to reduce molecule GP

Question 17

Describe the LIR

Answer 17

• CO2 reacts with RuBP
• Forms 2 GP, using Rubisco
• GP reduced to triose phosphate, using reduced NADP and energy from ATP
• 2 molecules of TP (per 12) go to make hexose
• 10 molecules pf TP (per 12) form 6 molecules RuBP
• all RuBP regenerated

Question 18

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

Answer 18

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

Question 19

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

Answer 19

• no CO2 reacts with RuBP
• so no GP

Question 20

Where is RuBisCo found in a cell?

Answer 20

• stroma of chloroplasts

Question 21

What is the role of NADPH in LIR?

Answer 21

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