1. Cycles of matter

2. Recycling is natural!
* The word cycle means to happen over and over again. In nature, the same building blocks are recycled in life processes because the amount on Earth is limited.
*You probably know about the water cycle, and we’ll explore the carbon and nitrogen cycles!
CYCLES GO
AROUND
AND AROUND

3. WATER CYCLE * Water is not living but is important to life.
* Water falls to the ground as a liquid during precipitation.
* Water seeps into the ground enters streams as runoff.
* The sun heats water up until it changes into a gas during evaporation.
* The gas is seen as clouds, which cool and release water as liquid AGAIN during precipitation.

4. MATTER RECYCLING
* Food webs show energy transfer, but when you eat, you also get nutrients to build your body.
* At the end of a food web, decomposers break down waste and put nutrients (like carbon and nitrogen) back into the soil for plants to use to grow.

5. CARBON CYCLE
* Carbon is an element found in inorganic molecules like CO2 gas. Plants use that gas to build sugars during photosynthesis. Animals use those sugars to build things like DNA. When animals die, decomposers release the carbon back to be used again by plants.

6. CARBON CYCLE * Three processes are the MAIN parts of cycling carbon.
1) Photosynthesis takes CO2 out of the air.
2) Respiration (plants and animals) puts CO2 back in the air.
3) Burning fossil fuels releases a LOT of CO2 into the air.

7. NITROGEN CYCLE
* Nitrogen is very important for building DNA and proteins. It is mostly found in the air and ONLY bacteria can directly use that. They help plants by putting nitrogen in the soil. Humans make fertilizers which are mostly nitrogen also. Sometimes too much fertilizer becomes like poison.

8. Summary Slide
Cycling is the continuous use and reuse of the same thing.
Water is cycled through precipitation and evaporation.
Carbon is cycled through photosynthesis and respiration, but burning fossil fuels disrupts the cycle.
Nitrogen is very limited, and bacteria are important for this cycle.