5.2.1 (g) factors affecting photosynthesis

Question 1

what factors affect the rate of photosynthesis?

Answer 1

light intensity
carbon dioxide concentration
temperature

Question 2

how does light intensity affect the rate of photosynthesis?

Answer 2

light is needed as an energy source so as it increases, more ATP and reduced NADP is produced so a higher rate of photosynthesis

Question 3

how does carbon dioxide affect the rate of photosynthesis?

Answer 3

increasing the CO2 concentration increases the rate of carbon fixation and therefore, more triose phosphate is produced therefore a greater rate of photosynthesis

Question 4

how does temperature affect the rate of photosynthesis?

Answer 4

as temperature increases, the rate of enzyme activity increases up until the protein denatures

enzymes such as RuBisCo and proteins like ATP synthase are important in photosynthesis

Question 5

why does water not affect the rate of photosynthesis?

Answer 5

it is not possible for there to be a low water potential unless the stomata remains closed

Question 6

what happens when light intensity falls in the Calvin cycle?

Answer 6

less light means less ATP and reduced NADP produced
so less GP is converted to TP
so GP accumulates while TP decreases
less TP means less regeneration of RuBP
so RuBP levels fall

Question 7

what happens when light intensity increases?

Answer 7

more light means more ATP and reduced NADP produced
so more GP is converted to TP
so GP decreases while TP increases
more TP means more regeneration of RuBP
so RuBP levels rise

Question 8

what happens when temperature is too low in the Calvin cycle?

Answer 8

lower kinetic energy in RuBisCo means less enzyme substrate complexes form so a reduced rate of reaction meaning concentrations of GP, TP and RuBP decreases

Question 9

what happens in the Calvin cycle when temperature is too high?

Answer 9

enzymes denature at high temperatures so no enzyme substrate complexes form meaning concentrations of GP, TP and RuBP decreases

Question 10

what happens to the Calvin cycle when CO2 concentrations decrease?

Answer 10

less CO2 means less fixation of carbon so less GP, TP is produced

however RuBP will accumulate as it is not being produced from TP but not being fixed by CO2

Question 11

what is a limiting factor?

Answer 11

something which inhibits the rate of reaction from increasing when in short supply

Question 12

what does increasing rate of photosynthesis donto pH?

Answer 12

increases pH
more CO2 used up
less H+ from photolysis