Give the composition of atphosphere and metion the importance of oxygen and water in it

The cell membrane (or plasma membrane) is composed mainly of phospholipids with embedded proteins. The membrane is a lipid bilayer, with the phospholipids oriented in a distinct manner to provide qualities necessary to maintain a cell in a water-based environment.

Dry air from Earth's atmosphere contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and traces of hydrogen, helium, and other "noble" gases (by volume), but generally a variable amount of water vapor is also present, on average about 1% at sea level.

c. 2,000 bce

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