There is a lot of competition. From food, water, shelter, mates... only the best, the organisms with the desirable traits survive. They survive and are able to reproduce, passing on their genes to the next generation. As this natural selection occurs, the traits that are necessary for survival are passed on, and over a long period of time this results in evolution.
Answer:
Enzymes help chemical reactions occur by decreasing the activation energy.
Mitosis splits 2 nuclei / 2 cells and meiosis gives 4
Oxidative Phosphorylation: Chemiosmosis and the Electron Transport Chain
