1. CYCLES OF
NATURE

2. Cycles of Nature
Nature's cycles have to do with
how the earth renews itself.

3. The living things within an ecosystem interact with each other and also with their non-living environment to form an ecological unit that is largely
self-contained.

4. Sometimes this renewal process is gradual and gentle.
Sometimes it is violent
and destructive.
Nevertheless,
ecosystems contain
within themselves the resources to regenerate themselves.

5. The Water Cycle
The movement of water between the oceans, atmosphere, land, and living things.

6. How
Water Moves
During evaporation, the sun’s heat causes water to change from liquid to vapor.
In the process of condensation, the water vapor cools and returns to a liquid state.

7. The water that falls from the atmosphere to the land and oceans is called precipitation.
rain
snow
sleet
hail
Most precipitation falls into the ocean.

11. How Important is Water?
Without water, there would be no life on Earth.
All organisms, from bacteria to animals and plants, are composed mostly of water.
Water helps transport nutrients and waste within an organism.
Water helps regulate temperature.
All water taken in by an organism is eventually returned to the environment

12. The Carbon Cycle
Besides water, the most common molecules in living things are organic molecules, or molecules that contain carbon.
The exchange of carbon between the environment and living things is known as the carbon cycle.

13. During
photosynthesis,
plants use
carbon dioxide
from air to
make sugars

14. Most animals get the carbon and energy they need by eating plants.
Plants and animals break down sugar molecules to release energy in a process called respiration.

15. Respiration uses oxygen and releases carbon dioxide and water back into the environment

16. Decomposition and Combustions
The breakdown of substances into simpler molecules is called decomposition.
For example, when fungi and bacteria decompose organic matter, carbon dioxide and water are returned to the environment.

17. Combustion is the process of burning a substance, such as wood or fossil fuels.
Combustion of organic matter releases carbon.

19. The Nitrogen Cycle
Living things need nitrogen to build proteins and DNA.
The movement of nitrogen between the environment and living things is called the nitrogen cycle.

20. Converting Nitrogen Gas
78% of the Earth’s atmosphere is nitrogen gas.
Most organisms cannot use nitrogen gas directly.
Bacteria in the soil are able to change nitrogen gas into forms that plants can use.
This process is called nitrogen fixation.
Other organisms get the nitrogen they need by eating plants or animals that eat plants.

21. Passing It On When organisms die, decomposers break down the remains.
Decomposition releases a form of nitrogen into the soil that plants can use.
Certain types of bacteria in the soil convert nitrogen to a gas.
This gas is returned to
the atmosphere.