Factors Affecting the Rate of Photosynthesis

Question 1

what are the factors that can change the rate of photosynthesis?

Answer 1

• the availability of the substrates for the reaction - carbon dioxide and water
• the energy available to allow the reaction to occur - light intensity
• the kinetic energy available to move substrates and enzyme molecules - increasing temperature increases kinetic energy

Question 2

what is the limiting factor?

Answer 2

the factor which is in shortest supply

Question 3

what happens when we add more carbon dioxide?

Answer 3

• the reaction can happen faster, as there are more molecules to collide with enzymes
• however, we reach a point when adding more carbon dioxide has no effect - there is a lack of energy

Question 4

what happens when we increase the light?

Answer 4

• this increases the energy for photosynthesis to occur
• this doesn’t last forever, as at high light intensities a different factor is limiting

Question 5

what happens when we increase the temperature?

Answer 5

• this gives the enzymes and substrates more kinetic energy to collide more often
• however, at high temperatures the rate of photosynthesis decreases as the enzymes start to denature