Science - The Cycling of Matter

This describes how rocks change over time due to weathering and erosion

This is anything that takes carbon out of the atmosphere

For example plants take carbon out of the atmosphere as carbon dioxide during photosynthesis

This explains how carbon is recycled through the Earth

1. Carbon dioxide is removed from the atmosphere by green plants during photosynthesis.  Plants store carbon

2. Plants are eaten by animals.  The carbon in the plant is absorbed by the animal

3. Plants and animals respire.  This releases carbon dioxide into the atmosphere

4. Animals produce waste.  Waste is broken down by decomposers in the soil.  This releases carbon dioxide into the atmosphere

5. When plants and animals die, their remains are broken down by decomposers.  This releases carbon dioxide into the atmosphere

6. If dead plants and animals are not completely broken down they may eventually form fossil fuels.  When fossil fuels are burned, they release carbon dioxide into the atmosphere

This is anything that releases carbon into the atmosphere

For example respiring organisms release carbon dioxide

This explains how nitrogen is recycled through the Earth

1. Approximately 80% of the air is nitrogen gas.  However, most of this nitrogen is not available to animals and plants

2. Certain bacteria, known as nitrogen-fixing bacteria, can change the nitrogen in the atmosphere into nitrates.  These nitrates can then be taken up from the soil by plants

3. The plant supplies the bacteria with food (sugars) and water

4. The plant uses nitrogen to form protein.  Animals get their protein by eating plants or other animals

5. Decomposers such as bacteria, fungi and earthworms return nitrogen to the soil as ammonium by breaking down dead organic matter

6. Denitrifying bacteria in the soil break down nitrates, returning nitrogen to the air