1. Plants and Their Adaptations
How Natural Materials are Reused
Plants and Their Adaptations

2. Natural Cycles Materials on earth are used and then reused
Air stores oxygen, nitrogen, and carbon dioxide
Rocks store iron, copper, magnesium, and calcium
Materials are used in various cycles
Erosion releases stored materials in rocks
These materials dissolve in water and become part of the soil
Animals drink the water to get some of the materials they need
Animals get most of the materials they need by eating
Animals release materials in their waste
Plants are part of these cycles
Plants get materials from soil and the air
Plants release materials into the air
After dying, plants and animals decay and release more materials into the environment
The cycles are continuous

3. The Nitrogen Cycle Nitrogen is needed by all organisms
Plants make proteins from nitrogen in the soil
Animals get nitrogen from these proteins
Atmosphere is 78% nitrogen
Most organisms can’t use this nitrogen
Nitrogen Cycle fixes or changes nitrogen into a form that plants can use (nitrates and ammonia)
Bacteria in the soil, nodules on roots of plants, and lightning can fix (change) nitrogen into a usable form
Nitrates and ammonia get returned to the soil
Solid waste of animals contain nitrates
Urine contains ammonia
Nitrates and ammonia are released when dead animals and plants decompose

4. Changing the Balance
Carbon dioxide-oxygen cycle stays in balance because of plants
The Industrial Revolution (when humans began to use machines fueled by wood and coal) started 200 years ago and has changed the balance of the carbon dioxide-oxygen cycle
Factories using huge amounts of fuels
Cutting down forests for lumber
Burning wood and coal
Mining for coal
Burning wood and coal has been replaced with natural gas and petroleum adding even more carbon dioxide to the air
Carbon dioxide is poisonous to animals and trees are still being cut for paper, lumber, and other human needs (farms, homes, cities)