Recognise that the atmosphere is a mixture of gases that blanket the Earth.
Evaluate how living organisms contribute to changes in our atmosphere. Appreciate that changes in atmospheric pressure affect weather.
The atmosphere is the layer of gases that blanket the Earth. The atmosphere is commonly known as air.
Gravity holds the atmosphere close to the Earth’s surface.
Argon, carbon dioxide and water vapour approximately 1%
Composition of the Air Oxygen 21%
The air in our atmosphere is a mixture of gases including nitrogen, oxygen, carbon dioxide, argon, water vapour and other gases.
As air is a mixture, the percentages of the gases it is made up of can change.
Nitrogen 78%
For example, humans and plants in a sealed room will change the composition of the air through respiration and photosynthesis. This is because these processes change the amounts of oxygen, carbon dioxide and water in the air.
Learn more about photosynthesis in Biological World 3.2
z 392 392 Fig. 22.4.2 The gases that make up air Learn more about respiration in Biological World 3.3
