Homeostasis is how the body controls things inside of us. For example our body temperature and percentage of water. It is important because it means our cells will be able to live properly and also bacteria strives best at 37 degrees celsius (body temperature).
No, that answer was kind of dumb. I would have to say amino acid.
Plants are regenerate energy sun heat carbon dioxide nature of photosynthesis
Synthesis of compounds with the aid of radiant energy
The diagram that would be used would be an energy pyramid.