1. Nutrient Cycling
Matter cannot be replenished like the energy from sunlight. Matter must be recycled.

2. Carbon Cycle
Carbon is found in the environment as carbon dioxide.

3. Carbon Cycle
Carbon dioxide is released during cellular respiration and used in photosynthesis
Carbon is also released during the burning of fossil fuels

5. Water Cycle Water occurs on Earth as a solid, liquid, and gas.
Water is used during photosynthesis
Water evaporates from leaves of the plants (transpiration). Plants take up water in their roots.

7. Nitrogen Cycle Nitrogen makes up almost 78% of air.
Nitrogen is needed for building proteins and DNA
Nitrogen in the air CANNOT be used directly…
IT MUST BE FIXED!!

8. Nitrogen Fixation
Nitrogen-fixing bacteria convert atmospheric nitrogen, N NH3
These bacteria live in the soil on the roots of legumes (bean plants)

9. Nitrogen Cycle Lightning also “fixes” nitrogen ~ although not a lot
Is lightning biotic or abiotic?
Is bacteria biotic or abiotic?