no plant or animal life can be found on mercury because there is not enough oxygen gravity.
plants "breathe" carbon dioxide which is what animals exhale. the plant life in the ocean provides oxygen for the marine life.
All life-they create oxygen.
The higher elevated the plant is, the less oxygen it receives. Different plants can tolerate less/more oxygen, which is why different plants exist in different elevations.
Plant waste product.
Sponges are considered ANIMAL life not plant life. Therefore they do not give off oxygen, they consume it.
The oxygen in Earth's atmosphere has been generated, over geological time, by the plant life on Earth.
It is diffused from the air, in the atmosphere, and from plant life in the ocean.
From plant life. Animals including humans exhale carbon dioxide. Carbon dioxide is a heavy gas and fall to the ground. Whereupon it is absorbed by plant life. Under the process of photosynthesis, carbon dioxide in the plant is broken down into carbon and oxygen. The carbon is retained in the plant as biomass, and the oxygen is released back into the atmosphere, for animals to breathe. It is all part of the oxygen/carbon cycle.
Oxygen for the survival of advanced life forms. Glucose for the energy of the plant. Water to sustain the plant's life, and drive chemical reactions.
The way to improve oxygen in the air is by increasing life that give off oxygen as a byproduct such as plant life. Animals use oxygen and give off carbon-dioxide which is used by plants which in turn releases oxygen in the air.
Green plant life generates oxygen through the process of photosynthesis. The leaves of trees is green plant life. Every tree that is eliminated eliminates the oxygen it was producing. The enormous tree cover in tropical forests create huge amounts of oxygen. As these forests are cleared away this oxygen is lost to the atmosphere.