The Cycles Presented by Mr. Rainbeau

III. The Cycles

A. The water cycle is the repeated movement of water between the Earth’s atmosphere, surface and living things

1. Evaporation – water changes from a liquid to a gas

2. Transpiration – how water evaporates from leaves

3. Respiration - breathing

4. Condensation - the process by which water vapor in the air is changed into liquid water (clouds)

5. Precipitation - water released from clouds in the form of rain, snow, or hail

6. Runoff- precipitation falls on the land, flows over land (runoff), and runs into rivers, which then empty into the oceans

Water cycles through not only abiotic, but biotic factors as well: –Transpiration –Perspiration –Breathing –Urination

B. The Carbon and Oxygen Cycles

B. The carbon and oxygen cycles are the repeated movements of C and O through an ecosystem

1. CO 2 in the air/water is used by plants, algae, and bacteria for photosynthesis

2. Carbon atoms return to the pool of CO 2 in the air in one of three ways

a)Respiration – nearly all organisms engage in cellular respiration and CO 2 is the byproduct

b)Combustion – Carbon returns to the atmosphere through burning.

1)Burning of fossil fuels ( Remains of organisms that became buried gradually transformed by heat and pressure into oil and coal)

Non-renewable!

c)Erosion – shells of dead organisms form limestone and as the limestone erodes the carbon becomes available

3. Carbon is stored in limestone, fossil fuels, and biomass in the ecosystem

C. Nitrogen Cycle is the pathway by which N moves through an ecosystem 1.Nitrogen is needed for: a)Proteins b) DNA & RNAc) ATP

2. Air we breathe is 78% nitrogen – but we cannot use this form

3. Four processes of the nitrogen cycle: a)Nitrogen fixation - the process that converts N 2 in the air into usable nitrogen compounds 1)nitrogen fixing bacteria in soil and roots convert N 2 into NH 3 (ammonium ions)

b) Nitrification - ammonium ions are changed into nitrates (done by nitrifying bacteria)

c)Ammonification - breaking down of Nitrogen compounds in remains of dead organisms (performed by decomposers)

d)Denitrification - conversion of ammonia or nitrates into nitrogen gas. (by Denitrifying bacteria) take nitrogen compounds in the soil and convert it into free nitrogen and returned it to the atmosphere