Factors which limit the rate of photosynthesis

Question 1

How does Temp effect rate of photosynthesis

Answer 1

Rate of photosynthesis increases as temp increases up to an optimum , after optimum it decreases.

Question 2

When does Temp become limiting

Answer 2

LIR is an enzyme controlled process. Increasing the temp up to optimum:
-more kinetic energy
-so more E-S complexes
However above optimum
-H bonds in tertiary structure break—>active site changes shape/ enzyme denatured
-So fewer E-S complexes

Question 3

How does light effect rate of photoysnthesis

Answer 3

Rate of photosynthesis increases as light intensity increases (then it plateaus)

Question 4

WHen does light become limiting

Answer 4

If light intensity was dramatically reduced:
levels of ATP and reduced NADP would fall because LDR limited as less photoionisation and less photolysis.
So less LIR as it would be slowed because :
-GP cant reduce TP (need ATP and reduced NADP)
-TP cant regen RuBP (requires ATP)

Question 5

How does CO2 effect rate of photosynthesis

Answer 5

RAte of photosynthesis increases as CO2 increases (then it plateaus)

Question 6

What happens when CO2 levels fall (limiting)

Answer 6

Limits LIR
so less CO2 combines with RuBP to form GP
Less GP reduced to TP
Less TP converted to useful organic substances e.g. glucose
Also cannot regenerate RuBP

Question 7

Common agriculture practices to overcome the effect of limiting factors

Answer 7

Light Intensity= artificial lights to maximise light intensity

Heating a greenhouse to increase the temp

Burning fuel (paraffin) to release more CO2

If limiting factor are minimal rate of photosynthesis will increase so:
Faster Production of glucose allowing faster respiration
More ATP to provide energy for growth
Higher yield so more profit