Module 5: Factors affecting photosynthesis

Question 1

Explain what is meant by a limiting factor

Answer 1

when one of the factors required for a plant to photosynthesise is in short supply , therefore it reduces the rate of photosynthesis

Question 2

What are the 3 factors that affect the rate of photosynthesis?

Answer 2

light intensity
carbon dioxide concentration
temperature

Question 3

State how temperature affects the rate of photosynthesis , giving an example of a process that it affects

Answer 3

temperature affects the rate of enzyme controlled reactions , in this case examples include carbon fixation during light independent photosynthesis

Question 4

How does increased temperature increase the rate of photosynthesis?

make 3 points

State what would occur if temperature was increased too much

Answer 4

A temperature increase will increase the kinetic energy of the enzymes and substrates , in this case rubisco , RuBP and carbon dioxide
This will increase the frequency of collisions and result in more enzyme substrate complexes
This will then result in the formation of more TP molecules

Enzymes would start to denature , which would decrease the rate of photosynthesis

Question 5

How does decreased temperature affect the rate of photosynthesis?

Answer 5

Enzymes and substrates will not have enough kinetic energy , resulting in fewer successful collisions and less enzyme substrate complexes
This will then reduce the rate of formation of TP molecules

Question 6

Describe how light intensity affects the rate of photosynthesis

3 points

Answer 6

reducing light intensity reduces the rate of the light dependent stage which will reduce the quantity of ATP and reduced NADP produced

the concentration of GP will increase and the concentration of TP will decrease as theres less NADPH to convert GP to TP
the concentration of TP will therefore decrease

there will be less TP to regenerate RuBP so concentration of RuBP will also decrease

Question 7

How does reduced carbon dioxide concentration affect the rate of photosynthesis?

Answer 7

this will reduce the concentration of GP and TP as there is less carbon dioxide to be fixed

the concentration of RuBP will increase as its still being produced from TP but not being used to fix carbon dioxide