1. The Cycling of Materials
Describe the short term and long term process of the carbon cycle.
Identify one way that humans are affecting the nitrogen cycle.
List the three stages of the nitrogen cycle.
Describe the role that nitrogen fixing bacteria play in the nitrogen cycle.
Explain how the excess use of fertilizer can affect the nitrogen and phosphorus cycles.

2. The Carbon Cycle
The carbon cycle is an essential component of proteins, fats, and carbohydrates, which make up all organisms.
Carbon Cycle – is a process by which carbon is cycled between the atmosphere, land, water, and organisms.

3. The Carbon Cycle

4. The short term cycle
When producers such as plants convert carbon dioxide in the atmosphere to carbohydrates during photosynthesis.
Cellular respiration then releases some of the carbon back into the atmosphere.

5. The long term cycle
Some of the carbon from the short term cycle may be converted into carbonates, which makes up the hard parts of bone and shell.
Because these items do not easily break down over millions of years they collect in huge deposits. With pressure they then form limestone.
The fats and oils in organisms is released when they die. These molecules can then for deposits of coal, oil, and natural gas. (fossil fuels)
Fossil fuels are essentially stored carbon left over from the bodies of plants and animals.

6. How humans affect the carbon cycle
When we burn fossil fuels we release carbon into the atmosphere. In the form of _________________.
What are some ways that humans release carbon into the atmosphere?
About half of the carbon dioxide released by humans remains in the atmosphere. And over time this builds up.
Increased levels of carbon dioxide leads to the _________________ effect.
What happens to the carbon dioxide that does not enter the atmosphere?

7. The nitrogen cycle All organisms need nitrogen to build proteins.
Nitrogen makes up 78% of the atmosphere.
Organisms can not use the nitrogen that is in the atmosphere.
The only organisms that can fix nitrogen are nitrogen fixing bacteria.

8. The nitrogen fixing process
Nitrogen fixing bacteria live in nodules on the roots of plants called legumes.
What are some examples of legumes?
The bacteria use sugars provided by the plants to produce nitrates.
Excess nitrogen is released into the soil

9. Decomposers and the nitrogen cycle
The nitrogen cycle is the movement of nitrogen between the atmosphere and living things.
When living things die bacteria break down their carcasses and release the nitrogen back into the soil and to the atmosphere.
What are some materials that contain nitrogen that have to be broken down by bacteria?

10. The phosphorus cycle
Phosphorus is part of many different molecules that make up the cells of living things.
Plants and animals get the phosphorus that they need from the water or from the food that they eat.
Phosphorus cycle – movement of phosphorus from the environment to organisms and then back to the environment.
This cycle does not normally occur in the atmosphere because phosphorus is a rarely a gas.

11. Phosphorus Cycle How can phosphorus enter the soil? Many phosphates
do not break
down and
collect at the
bottom of
the ocean
as sediment.

12. Problems with the nitrogen and phosphorus cycles
What are some problems that occur when there is to much nitrogen and or phosphate in an area?
What is a major source of excess nitrogen and phosphorus?