1. Natural Cycles

2. The cycles of matter
Imagine an aquarium containing water, fish, snails, plants, algae, and bacteria. The tank is sealed so tight that only light can enter. Food, water, and air cannot be added. Will the organisms in this environment survive?
Through photosynthesis, plants and algae make their own food. They also supply oxygen to the tank.
Wastes from fish and snails fertilize the plants and algae.
Fish and snails take in oxygen and eat plants and algae.
Organisms that die are decomposed by the bacteria.
They can survive because the materials are being recycled!

3. The cycles of matter
Earth’s biosphere also contains a fixed amount of water, carbon, nitrogen, oxygen, and other materials required for life.
These materials are constantly cycled through the environment to be used over and over again.

4. Cycles in Nature The water cycle The carbon-oxygen cycle
The nitrogen cycle

5. Water cycle the movement of water on, in, and above the earth.
Water is always changing state and moving from one place to another.

6. Where is water found? Living things – very little trapped here
Oceans, rivers, lakes – substantial percentage
Atmosphere – water vapor
Groundwater – soaked under the ground

7. Water Cycle evaporation – sun changes water from liquid to gas
The sun heats up water in rivers, streams, oceans, and lakes and turns it into vapor or steam. This water vapor rises into the air.

8. Water Cycle
transpiration – water is evaporated from plant pores

9. Water Cycle condensation – water changes from a gas to a liquid
Water vapor cools down and changes back into liquid water droplets. These droplets clump together to form clouds.

10. Water Cycle
precipitation – water that falls from the atmosphere to the land or ocean (rain, sleet, hail, snow)
When the water droplets in clouds become large and heavy enough, they fall to the Earth.

11. Water Cycle
Some of the precipitation that falls on land flows into streams, rivers, and lakes and is known as runoff.
Other precipitation is absorbed into the ground and is stored as groundwater. This water will slowly flow back into the soil, streams, rivers and oceans.

12. Water Cycle

13. The carbon-oxygen cycle

14. The carbon-oxygen cycle
photosynthesis – plants take in carbon-dioxide and give off oxygen

15. The carbon-oxygen cycle
respiration – animals take in oxygen and give off carbon-dioxide
CARBON-
DIOXIDE
OXYGEN

16. The carbon-oxygen cycle
decomposition – fungi and bacteria break down matter which produces carbon-dioxide

17. The carbon-oxygen cycle
combustion – burning wood or fossil fuels which give off carbon-dioxide.

18. The carbon-oxygen cycle
Photosynthesis
Respiration
Decomposition
Combustion
Carbon-dioxide
Carbon-dioxide
Carbon-dioxide
Do you see a problem?

19. The Nitrogen Cycle
78% of the air we breathe is made of nitrogen gas. Even though this gas is all around us, we and other organisms can’t use it.
In the nitrogen cycle, nitrogen gas is converted into other forms and back to gas again. N₂

20. The Nitrogen Cycle

21. Nitrogen-fixing bacteria
The Nitrogen Cycle
nitrogen fixation – changing nitrogen gas into forms that plants can use.
Nitrogen-fixing bacteria
Lightning

22. REVIEW
In the nitrogen cycle, __________________ will change nitrogen in the air into nitrates that plants can use.
In the nitrogen cycle, _________________________ will change nitrogen in the ground into nitrates that the plants roots can take in and use.
In the carbon-oxygen cycle, plants take in ___________________ and release or give off ___________________________.
In the carbon-oxygen cycle, animals breath in ______________________ and release ___________________.