Heliophytes : The plants that thrive in area where intensity of light is more are called heliophytes e.g. Dalbergia.
Sciophytes : The sciophytes need less intensity of light and they grow under the canopy of trees. These plants have less amount of chlorophyll and remain smaller due to decreased rate of photosynthesis e.g. Oxalis.
Saturation point is the maximum intensity of light at which the rate of photosynthesis is maximum. Above this value of light intensity, rate of photosynthesis decreases.
Value : It is 60–70% for C3 plants and about 200% of full sunlight for C4 plants.
Affect of CO2 on photosynthesis : Carbon dioxide acts as a major limitin factor for photosynhesis. The CO2 is 0.03 % in atmosphere and increase in amount of CO2 upto 0.05% in atmosphere increases the rate of photosynthesis. Beyond it the rate declines. It is due to the increase in the temperature.
The C3 and C4 plants responds differently o the CO2 concentration. The C3 plants respond to a higher concentration of CO2 by showing increased rates of photosynthesis while the C4 plants saturate at low level of CO2 and do not show increase in the rate of photosynthesis.
Describe very briefly the contribution of the following scientists :
(1) Jan Ingcnhousz
(2) C.B. Van Niel
(3) Joseph Priestly
(2) C.B. Van Niel, proposed that the oxygen produced during the photosynthesis comes from water and not carbon dioxide.
(3) Joseph Priestly reported that green plants purify the air and restore to the air whateever the burning of candle or breathing animals remove from the air.
Name the pentose phosphatew which is a CO2 acceptor in the dark reaction of photosynthesis ?