Light energy absorbed by chlorophyll is converted into chemical energy. Some of this energy is used to split water into hydrogen and oxygen. Some of the chemical energy is used to make ATP from ADP and phosphate (Pi). This chemical energy is stored as ATP.
Homeostasis is the attempt to maintain stable conditions (particularly in an organism). It is done by using feedback loops (positive and negative).
Vitamin A deficiency is the leading cause of preventable blindness in children.
Mitocondria, the power house of a cell.