CYCLES IN NATURE

Objectives:1)Define the term “Cyclical”2)Identify three cycles in our

natural world3)Describe these cycles in detail

CARBON CYCLE All living things on earth (Plants and Animals) are

made of carbon. Animals breathe in oxygen and release CO2

Carbon Dioxide can be found in the air. Plants use Carbon dioxide and the energy from the sun (photosynthesis) to grow. They then release O2 (oxygen)

Burning wood and fossil fuels (coal and oil is ancient petrified organisms held under extreme pressures in the earth) increases CO2 in the atmosphere

CO2 is a greenhouse gas that causes global warming when too much is trapped in the atmosphere

CARBON CYCLE Carbon Dioxide is known as a green

house gas.

THE WATER CYCLE

The continuous movement of water from the earths surface into the atmosphere and back

Evaporation, condensation and precipitation make up the water cycle

EVAPORATION/TRANSPIRATION

Liquid water from oceans, lakes and even plants and animals receive energy from the sun and turn to water vapor. This water vapor rises into the atmosphere

CONDENSATION

As the water vapor rises into the atmosphere it begins to cool and turns back into a liquid form.

PRECIPITATION

As the water begins to condense, clouds form. Eventually the water begins to fall back onto the earth surface as precipitation (rain, snow, hail)

Most precipitation falls back into oceans or lakes.

The rest may fall onto land where it seeps into the ground (Groundwater) where it is reabsorbed by plants. It may also flow from land to lakes, streams and oceans by a process called runoff.

THE NITROGEN CYCLE

Nitrogen is also an important element in life. Proteins, DNA and many other structures in the body need nitrogen.

Nitrogen is the most abundant gas in the air (78%)

However, nitrogen gas cannot be used by most living organisms. It must be “fixed”

NITROGEN FIXATION

Bacteria use the nitrogen gas found in air and create nitrates, which can then be used by plants. Some plants have even developed a symbiosis with bacteria to acquire these nitrates.

Animals then eat plants (or other animals) for their nitrogen uptake.

DECOMPOSITION

Bacteria also decompose plant and animals, releasing their nitrogen (as well as carbon) back into the atmosphere and earth.