Question : The reactions of photosynthesis make up a biochemical pathway. Explain how the biochemical pathway of photosynthesis recycles many of its own reactions and identify the recycled reactants.

Question : The reactions of photosynthesis make up a biochemical pathw

1.	Question : The reactions of photosynthesis make up a biochemical pathway. Explain how the biochemical pathway of photosynthesis recycles many of its own reactions and identify the recycled reactants.
Answer» Solution :The ATP and `NADPH_2` are generated during light reaction of photosynthesis. (i) They help in reduction of CARBON dioxide to carbohydrates and during the process they are converted to ADP and NADP. (ii) They are sent back to the GRANA of chloroplast to form ATP and `NADPH_2`. (iii) Similarly the `CO_2` from the atmosphere is said to be fixed by a `CO_2` acceptor molecule. (IV) During successive reactions the carbon of `CO_2` is used for formation of glucose and the original acceptor molecule is recycled so that it can again help in `CO_2` fixation. (v) WATER is split during light reaction and oxygen is produced as a by-product. (VI) At the same time water is again released as a by-product of dark reaction. (vii) Thus many molecules such as ATP, `NADPH_2`, water, `CO_2` acceptor molecules are recycled during the biochemical pathway of photosynthesis.