Cycles Found in Nature

The first cycle mentions is a complete Food Web in which scavengers and decomposers convert all dead biotic material into reusable materials. Such material is often referred to as fertilizer. Also dead material may become the food for other creatures especially insects which will lay eggs in the decaying flesh so that the hatching young have a ready available supply of food. Bacteria and fungi will continue the complete breakdown of the complex cellular structure of these once living cells.
This cycle is called the Nutrient Cycle. In this cycle, material moves from the producer to the consumer and eventually some of this material is returned to the producers by decomposers. Comprises food chains and webs if the decomposers are included. Three other important cycles found in nature are

the water cycle. A diagram may be found here

the carbon cycle. A diagram may be found here

the nitrogen cycle.

the phosphorus cycle (just mentioned, not studied). In each of these cycles water, carbon (the building block of all life) and nitrogen (an essential component of amino acids) are used then returned to the environment to be reused again and again.

Cycles in Nature

Law of Conservation of Matter

Matter cannot be created nor destroyed in any chemical reaction. It can only be transformed from one form to another.

Cycle - A cycle shows the reusing of certain elements and compounds (e.g. water, carbon, oxygen, nitrogen, phosphorus) in different forms in ecosystems.

WATER CYCLE

The sun provides the heat energy required for the cycle to continue.
The oceans and rivers are the main reservoirs of water.
Evaporation - Water evaporates into the atmosphere.
Condensation - Water condenses into droplets in the clouds.
Precipitation - As the water droplets in clouds enlarge, water falls to earth in the form of rain, snow or hail.
Transpiration - Water is lost through the leaves of plants ('trees perspiring').

CARBON AND OXYGEN CYCLES

Carbon occurs in all living organisms in the forms of carbon dioxide, carbohydrates (sugars and starches), proteins and fats.
Oxygen occurs in all living organisms in the forms of oxygen gas, water, carbon dioxide, carbohydrates, proteins and fats.
Photosynthesis - Photosynthesis is the process used by plants containing chlorophyll to utilise sunlight, carbon dioxide and water to form sugar (as glucose) and oxygen.

Carbon Dioxide + Water Glucose Sugar + Oxygen

CO₂ + H₂O C₆H₁₂O₆ + O₂

Respiration - Respiration is the process that most living organisms (including animals, plants, fungi and micro-organisms) use to obtain energy from glucose sugar and oxygen. The wastes formed are carbon dioxide and water.

Glucose + Oxygen Carbon Dioxide + Water + Energy

C₆H₁₂O₆ + O₂ CO₂ + H₂O + Energy