Introduction: All of the world around us is continually involved in cycles of some sort or another. For example, the cycle of seasons, the cycle of life, the geological cycle, the reproductive cycle, etc. There are three cycles, however, that are responisble for the cycling of those key elements that make up all life: carbon, hydrogen, oxygen, and nitrogen (C,H,O,N). Every living organism needs these elements on a continual basis in order to survive. Without them being continally renewed on our planet, life could not exist. The three cycles responsible for providing the continual flow of these elements are: the water cycle, the carbon-oxygen cycle, and the nitrogen cycle.

Directions: You are to diagram and label each of the three cycles in nature.

Use arrows to indicate the direction of movement in each part of the cycle. Make them neat, organized, and clear. You will be required to use these diagrams for future activities and exams. 

1. Know and include the following terms in your water cycle diagram:

precipitation evaporation transpiration

water table ground water surface water

runoff absorbtion leeching

2. Describe problems when parts of the cycle are missing or out of balance.

1. Know and include the following terms in your carbon-oxygen cycle diagram:

photosynthesis respiration

combustion atmospheric carbon dioxide (CO2) decomposition atmospheric oxygen (O2)

stored carbon (include vegetation, animals, rocks, oceans)

With the arrows indicating the direction of movement of the elements,

label the elements in motion.

2. Describe problems when parts of the cycle are missing or out of balance.

1. Know and include the following terms in your nitrogen cycle diagram:

atmospheric nitrogen (N2) nitrogen fixation (lightning, bacteria) nitrification (nitrifying bacteria) ammonia (NH3)

usable nitrates (NO3) absorbtion

decomposition ammonification denitrification (denitrifying bacteria) stored nitrates (vegetation, animals)

2. Describe problems when parts of the cycle are missing or out of balance.