The Water Cycle

(Water is needed by organisms to carry out chemical reactions and to maintain homeostasis.)

  1. Evaporation is the process in which liquid bodies of water, such as ponds, lakes, rivers, and oceans, change into water vapor.
  2. Transpiration is the evaporation of water from plant leaves.
  3. Condensation is the next process. In condensation the water vapor changes to liquid water or ice. The clouds are formed due to condensation.
  4. Precipitation is when the water condenses so much that it falls to the ground in the form of rain, snow or hail.
  5. Once the precipitation falls to the ground, the water may flow onto the ground or underground into lakes, streams, rivers, oceans, or ponds. Once in these bodies of water, evaporation occurs and the process starts all over again.
  • Label the water cycle on your worksheet, using the descriptions listed above. Beside each label, define the process. (i.e. evaporation = liquid water changing to water vapor.)

The Carbon Cycle

(Organisms need carbon to build their bodies, and it is the main ingredient in sugar which is what we eat.)

  1. Carbon begins in the atmosphere as Carbon Dioxide.
  2. Plants on land, and algae in the water, take in the carbon dioxide during the process of photosynthesis. They use this carbon dioxide to make their own food.
  3. Animals eat the plants and get the carbon from the plants during feeding.
  4. Both animals and plants die, and the carbon from their bodies goes back into the soil during decomposition.

OR…Animals breathe out carbon dioxide during the process of respiration.

  1. Over millions of years, the carbon in their bodies can change into fossil fuels like coal, oil, and natural gas.
  2. When people drive cars, or burn fossil fuels (like in factories), the carbon is converted back to carbon dioxide gas, in the atmosphere, and the process starts all over again.

*Using the descriptions listed above, and your worksheet as a guide, draw your own carbon cycle, only using the six steps I’ve provided.

The Nitrogen Cycle

(Organisms need nitrogen to make their DNA and their proteins!)

  1. Nitrogen gas (N2) is found in the atmosphere. (About 79% of the air is composed of Nitrogen gas.)
  2. Nitrogen gas cannot be used by animals or plants so it has to be changed into a solid form. This is done one of two ways…
  3. Nitrogen gas is taken in by bacteria in the soil during the process of nitrogen fixation, and the nitrogen gas is converted to ammonia (NH3)
  4. Nitrogen gas is converted to ammonia when lightening takes it from the atmosphere and puts it into the soil.
  5. The ammonia is then converted into nitrates (NO3- and NO2-) by nitrifying bacteria. (On your picture, it is the circle between NH3 and NO3, NO2.)
  6. The nitrates are then taken in by plants (producers) to build their DNA and proteins.
  7. Animals eat the plants and get the nitrogen they need to build their DNA and proteins.
  8. Animals and plants die and poop and their bodies and waste can be converted back to ammonia (NH3), through the process of decomposition.
  9. Finally, the ammonia (NH3) is converted back to nitrogen gas in the atmosphere by the process of denitrification.

*Using the descriptions listed above, and the worksheet to draw your own nitrogen cycle using the steps I’ve provided.

Finally, complete the worksheet according to the directions provided on the worksheet.