The peas haven't start germinating, which means no leaves. They can't undergo photosynthesis to produce oxygen. At this stage they are still undergoing respiration, which produce carbon dioxide.
A water molecule consists of two atoms of hydrogen linked by covalent bonds to the same atom of oxygen. Atoms of oxygen are electronegative and attract the shared electrons in their covalent bonds.
Actually a living thing is not a system. Every part of our body, like our lungs brain or heart, can be seen as a separate system. Therefore we are giant arrays of systems working together to keep you alive
Well it helped the animals and humans grow the population.
