A because people can't see the seeds.
There are many different factors, but some are: the amount of natural resources (food, water, etc.), amount of predator/prey, and availability of shelter.
This is a cellular respiration question, related to biology.
Some processes in our bodies require the use oxygen, others do not.
In this case, the conversion of pyruvic acid to acetyl co-enzyme A and the production of water in the electron transport chain do require oxygen.
If oxygen was not present for pyruvate, it would turn into lactic acid via fermentation. Water in the ETC is formed in the process when NADH and FADH2 are converted to molecular oxygen due to the electron transporters. The protons are then pumped and oxygen is reduced to form H2O.
Water molecules bond to each other in a covalent bond where they stay connected. They also have poles like a magnet, making it a polar molecule.
If water is no longer polar the surface tension would lower to the point where ice can no longer float, the water would freeze, cooling the climate considerably.
