factors affecting photosynthesis

Question 1

what are the limiting factors on photosynthesis?

Answer 1

-carbon dioxide concentration
-light intensity
temperature

Question 2

explain the law of limiting factors

Answer 2

when a process is influenced by several factors, the rate at which the process proceeds is determined by the factor in the shortest supply

Question 3

explain the effects of light intensity on photosynthesis

Answer 3

1. low light: limits light dependent stage so not much ATP and reduced NADP produced= slows light independent stage = low photosynthesis
2. intermediate light intensity= more ATP and reduced NADP in light-dependent stage= generates RuBP in the light independent stage more quickly = more GP converted to TP and rate of photosynthesis increases
3. high light intensity= more light than needed so another factor e.g temp becomes limiting and so rate plateaus

Question 4

what is light compensation point

Answer 4

-when volume of oxygen produced and CO2 absorbed in photosynthesis is balanced by o2 absorbed and co2 produced by respiration

Question 6

explain the effect of CO2 concentration on the rate of photosynthesis

Answer 6

1.low CO2 concentration= limits light independent reaction as less CO2 is fixed- reducing production of GP and TP: rate of photosynthesis is low

2. intermediate CO2 concentration= allows faster production of GP and TP increasing rate of photosynthesis
3. high CO2 concentration: another factor like light becomes limitting

Question 7

what can cause closure of stomata

Answer 7

prolonged exposure to CO2 concentration of above 0.5% can cause closure of stomata

Question 8

how can farmers increase the yield oof crop plants in greenhouses

Answer 8

increasing the co2 concentration and temperature in a glasshouse can be achieved by burning high quality paraffin= burns without producing unwanted fumes and produces CO2 and heat at the same time

Question 9

explain the effect of temperature on rate of photosynthesis

Answer 9

-temperature affects the enzymes involved in the Calvin cycle
-10 degrees temp rise (within 10-30 degrees) will lead to a doubling of the rate of photosynthesis
-25 degrees is considered optimum temp (kinetic energy for enzyme reactions)
-above 30 degrees growth rates reduce due to photorespiration
-above 45 degrees enzymes are denatured

Question 10

what is photorespiration

Answer 10

o2 competes with CO2 for rubisco’s active site