We de-starch leaves so as to remove the starch produced in it during photosynthesis stored as food. Removing the starch would help us to infer our observations clearly as there is no change or substance that would effect the experiment we want to carry out. For example , the indicators we use might give blue-black or green colors just because of the presence or absence of starch.
It is a part of the cell cycle.
They are the managed consumption of natural resources to prevent their depletion or the destruction of the environment.
