1.
THE CARBON CYCLE

3. What is carbon? Carbon is a very abundant element.
It exists in pure or nearly pure forms – such as diamonds and graphite – but can also combine with other elements to form molecules.
These carbon-based molecules are the basic building blocks of humans, animals, plants, trees and soils.
Some greenhouse gases, such as CO2 and methane, also consist of carbon-based molecules, as do fossil fuels, which are largely made up of hydrocarbons (molecules consisting of hydrogen and carbon).

4. A. What is the Carbon Cycle?
The Carbon Cycle is a complex series of processes through which all of the carbon atoms cycle.
The same carbon atoms in your body today have been used in countless other molecules since time began.

5. How is carbon cycled through the environment?
The wood burned just a few decades ago could have produced carbon dioxide which through photosynthesis became part of a plant.
When you eat that plant, the same carbon from the wood which was burnt can become part of you.
The carbon cycle is the great natural recycler of carbon atoms.

7. B. Plants in the Carbon Cycle:
Plants are producers because they produce their own food
In the carbon cycle, plants absorb (take in) carbon dioxide from the atmosphere and use it, combined with water they get from the soil, to make the substances they need for growth
This process of photosynthesis incorporates the carbon atoms from carbon dioxide into sugars—the food the plants (producers) use for energy

9. C. Animals and People in the Carbon Cycle:
Plants/animals are consumers because they CONSUME other plants and animals
Animals, such as rabbits, eat plants & use the carbon to build their own tissues.
Other animals, such as the fox, eat the rabbit and then use the carbon for their own needs.
Animals return carbon dioxide into the air when they breathe, which is part of respiration
When people burn fossil fuels, it is called combustion.
When animals die, the carbon is returned to the soil during decomposition.

10. D. Bacteria and Fungi in the Carbon Cycle
Bacteria and fungi are decomposers involved in the carbon cycle
They break down organic material (anything living or once living)
Ex. dead animals or leaves.
They release carbon dioxide, as well as methane (a hydrocarbon), to the atmosphere and soil

12. E. What happens to the carbon from dead stuff?
Sometimes the decomposers don't break down organic material—all the living or once living stuff.
This organic material is made into fossil fuels over thousands of years with the help of heat and pressure from the inside of the earth where it is buried.
3. The source of carbon in fossil fuels comes from the remains of plants and animals (mostly bacteria and plants) that died long ago.
These fuels—oil, natural gas, coal, etc, are being dug out of the earth and used, returning the carbon to the carbon cycle.

13. Continued
Since the Industrial Revolution, humans have greatly increased the quantity of carbon dioxide found in the Earth's atmosphere and oceans.
Emissions from fossil fuel combustion account for about 65% of the additional carbon dioxide currently found in the Earth's atmosphere.
Humans have altered the carbon cycle through fossil fuel burning, deforestation (cutting down of trees), and land-use change, such as from farming to building homes.

15. Finally…….
The same carbon atom can move through many organisms and even end up in the same place where it began.
Thus, lies the fascination of the carbon cycle: The same atoms can be recycled for millennia!