RuBP,GP and TP levels

Question 1

Explain effect of GP and RuBP in light vs dark

Answer 1

• In light GP and RuBP are at steady level
• In light, RuBP converts to GP, converts back again
• In darkness, GP accumulates and levels of RuBP falls
• Reduced GP needed to convert to TP requires ATP and NADPH from LDR
• Can’t form TP
• Can’t regenerate RuBP
• GP accumulates , RuBP levels fal

Question 2

Explain why

RuBP increases when concentration of carbon dioxide decrease?

Answer 2

There is less of carbon dioxide ro convert RuBP into GP

RuBP accumulates

Question 3

Explain why GP and TP decrease when carbon dioxide increase?

Answer 3

GP is not made from RuBP but is being converted into TP and so being used up

GP runs out so less TP made

But TP is still being converted to carbohydrate so TP is used up

Question 4

Effect of changing light intensity

Why RuBP and TP decrease when light intensity decreases?

Answer 4

GP is not being made into TP because of the lack of TP due to ATP and NADPH

TP converted into carbohydrate and RuBP which uses up TP

TP is being used up less RuBP can be made but RuBP is still being converted to GP

RuBP gets used up

Question 5

Effect of changing light intensity

Why does decreasing light intensity increases GP

Answer 5

• There is enough light to make ATP to convert GP into TP in high light intensity
• But in low intensity the plant cannot covert as much GP to TP as there is not enough ATP and NADPH
• Hence GP accumulates

Question 6

What happens to TP when light intensity decreases?

Answer 6

• Decreasing light intensity means less ATP and reduced NADP
• Less TP made since ATP and NADPH neeeded to make TP from GP

Question 7

What happens to GP when light intensity decreases?

Answer 7

• More GP
• RuBP can be converted to GP without ATP
• Reduced NADP GP will not be used to make TP

Question 8

What happens to RuBP when light intensity decreases?

Answer 8

• Less ATP and reduced NADP
• Less RuBP
• RuBP used to make GP
• RuBP not regenerated as GP to make TP
• Which is needed to make more RuBP

Question 9

What happens when carbon dioxide increases with TP?

Answer 9

TP increases

More CO2 is fixed so more GP is made so more TP

Question 10

What happens when carbon dioxide concentration increases with GP?

Answer 10

• As carbon dioxide increases
• GP increases
• More CO2
• More GP made

Question 11

What happens when carbon dioxide concentration increases with RuBP?

Answer 11

• RuBP decreases
• More CO2 fixed
• More GP is made
• More RuBP used up

Question 12

What happens as temperature increases with TP?

Answer 12

TP increases

At high temp , TP decrease because Rubsico denature

Less CO2 fixed

Less GP made

Less TP made

Question 13

What happens as temperature increases with GP?

Answer 13

More GP

At high temp - decrease

Enzyme rubscio denature so less carbon dioxide fixed

Less GP made

Less TP made

Question 14

What happens when temperature increases with RuBP?

Answer 14

RuBP decrease because rate of enzyme action increases more RuBP used up

When Rubscio denature when high temp , less RuBP used up as CO2 not fixed