The carbon cycle is the way carbon (iv) oxide is being used from the atmosphere by photosynthesis and put back into the atmosphere by respiration and decay. The carbon cycle involves the following processes: Photosynthesis, Respiration, Putrefaction and Combustion. Only photosynthesis removes carbon (iv) oxide from the atmosphere; the other three processes return carbon (iv) oxide to the atmosphere

1. Photosynthesis: The air contains carbon (iv) oxide which diffuses into the leaves and it built up into sugar and other complex compounds. When the plant is eaten by animal, sugar gets into the cells in the animal’s body.
2. Respiration: Within the animal body when the chemical food substance is broken down, it releases carbon (iv) oxide, water and energy. The carbon (iv) oxide is released to the atmosphere.
3. Putrefaction: When animals and plants die, they decay. In the process of decay, bacteria and other microbes feed on them. The bacteria and other microbes too respire, therefore returning C0₂ back to the atmosphere
4. Combustion: carbon (iv) oxide is also released into the atmosphere when fuels such as coal, wood, petrol, and kerosene are burned
5. From the sea: Where there is little quantity of carbon (iv) oxide in the atmosphere, more is liberated from the seas. Conversely, when there is too much carbon (iv) oxide in the atmosphere, more dissolves in the sea

          Importance of Carbon Cycle

• All living things are made up of a carbon component
• All food components contain carbon in the item
• The process produces carbon (iv) oxide for the use of photosynthesis
• The process maintains carbon-oxygen balance in the atmosphere

Water Cycle

The water cycle is defined as the way water is used and returned to the atmosphere in the form of water vapour to fall back as rain. The water cycle involves two processes, namely condensation and evaporation. When rain falls, some of it is absorbed by plants through their root hairs.

After spending some time in plants, water evaporates from them in the process of transpiration. A lot of the water is drunk by animals, which they use to release water vapour to the environment during respiration and excretion. Some of the rain falls directly into ponds, streams, and rivers. Some of the water filters down through the soil and forms underground water empties into the oceans. Water returns to the atmosphere by evaporation. When water vapour accumulates in the atmosphere as cloud when it reaches the condensation level, where it may fall once again as rain.

         Importance of water to plants

1. it cools the plant during the process of transportation
2. It serves as an agent of weathering for soil formation
3. It aids the germination of seeds
4. It helps to dissolve plant nutrients for easy absorption by the plant
5. Water is required for photosynthesis to commence
6. It gives plant support through rigidity

           Importance of water to animals

1. It is the main component of an animal
2. It is the solvent for soluble food substances to dissolve during digestion
3. It is a medium of transportation for nutrients
4. It constitutes a large part of the blood
5. it aids excretion and regulates body temperature
6. It is the basis for the body’s secretions, such as hormones and enzymes
7. It is the medium in which biochemical reactions can take place in living organism.