Download Oxygen Cycle

Date: Thursday, July 2nd 2015
Topic: Oxygen in Nature / Oxygen Cycle
Objective: To fathom the importance of Oxygen and to identify the
five stages of the Oxygen Cycle.
CLASS # 4 – U2
OXYGEN IN NATURE / OXYGEN CYCLE
Oxygen in Nature
Oxygen occupies, approximately, the 21% of the
atmosphere. It is the most important gas from the biological
point of view, since it is used by living things to breathe.
It may be found in its free form (O2) or form by other
compounds, like Water (H2O)
This gas comes from the Photosynthesis made by algae in
the Hydrosphere and by green plants in the Lithosphere.
Oxygen Cycle
The Oxygen Cycle is a chain of reaction that describe the
circulation of the oxygen in the atmosphere, the hydrosphere,
the lithosphere, and the biosphere, as shown below:
1. It begins when plants
absorb H2O and CO2 and
make the Photosynthesis
photosynthesis
2. Oxygen is released and
goes back to Air and Water.
3. The O2 circulates
among the living
things.
CO2
breathing
5. The terrestrial organisms
release water vapor and
CO2 that goes into the
Carbon Cycle
organic
compounds in
decomposition
4. The O2 is used to
breathe (Respiration
Process).
Practice # 3
Answer the following questions:
1. Explain the importance of the Oxygen in Nature?
2. How many stages does the Oxygen Cycle have?
Explain what happens in the third stage.
3. After what you have learned, how are Oxygen and
Carbon connected?