2. 4.1 – The Carbon/Oxygen Cycle
4.2 – The Nitrogen Cycle
4.3 – Phosphorus and ___ Cycle
Cycles of Life
All life requires nutrients and nutrients are
continually recycled … if they were not, they
would become used up and life on Earth
would cease to exist.
3. 4.1 – The Carbon/Oxygen Cycle
The Carbon/Oxygen Cycle is interconnected
and involves three major processes and one
minor process:
1. Photosynthesis
2. Respiration
3. Combustion
4. Decomposition
4. 1. Photosynthesis
Green plants/trees take in carbon dioxide
and water using the chlorophyll in their
leaves and energy from the sun they
release oxygen, sugar and water vapor.
9. 3. Combustion
This is the process of burning. When
combustion occurs CO2 is released into
the atmosphere. Natural combustion
includes volcanic eruptions, however
most pollution problems occur
because cars and factories
release CO2 by their burning
fossil fuels.
11. 3. Combustion
During the Carboniferous Period (300
mya) large amounts carbon (in the tissue
of plant matter) was trapped underground.
Because of lack of oxygen and
tremendous pressure, the plant matter
was compressed into fossil fuels.
12. 3. Combustion
Combustion due to fossil fuels over
contributes to the carbon cycle, which is
accelerating the negative effects of
global warming.
13. 4. Decomposition
When an animal or plant dies all the carbon,
oxygen, nitrogen, water, calcium etc. return
to the soil and air during decomposition.
Certain insects, fungi and bacteria aid in the
decomposition process and are called
decomposers.
