Answer:

The air in the atmosphere consists of nitrogen, oxygen, which is the life-sustaining substance for animals and humans, carbon dioxide, water vapour and small amounts of other elements (argon, neon, etc.). Higher in the atmosphere air also contains ozone, helium and hydrogen.
Membranes are barriers and “gatekeepers”, they only let certain molecules pass through them.
they also transport nutrients to the cell
Answer:Water contains Oxygen the purified the methane gas
Explanation: