1)Give effect of light intensity on photosynthesis.
2)What is cyclic photo phosphorylation.
3) Which are the organelles that are capable of utilising oxygen directly?
4)Give difference between C3&C4 plants.

Solution:

1. As the intensity of light increases, the process of photosynthesis increases. But after reaching a certain extent though light intensity increases photosynthesis cannot increase more. At very high light intensity chlorophyll may get damaged and the rate may fall down steeply.

2. Photophosphorylation is of two types cyclic and non-cyclic. In cyclic photophosphorylation Photon from the light excite an electron from the reaction center P680. This electron is than passed through ferredoxin to cytochrome b6f where phosphorylation of ADP to ATP take place and than it passes to the plastocyanin which return the electron to reaction center P680. In cyclic photophosphorylation, electron comes back to the reaction center.

3. Mitochondria is capable of utilising oxygen directly.

4. Differences are as follows:

C3 Plants	C4 Plants
These plants lack bundle sheath cells, only mesophyll cells are present.	These plants have two types of photosynthetic cells - mesophyll & bundle sheath cells.
Same type of chloroplasts are present.	These have dimorphic chloroplasts.
Primary acceptor of CO2 is accepted 5 carbon compound i.e- Ribulose-1,5 bi phosphate.	Primary acceptor of CO2 is phosphoenol pyruvate.
First stable compound is 3 carbon molecule	First stable compound is 4 carbon molecule.