The element carbon is the present in all living organisms. It's recycled through various processes, which are described in the carbon cycle.

Nitrogen is essential for the formation of amino acids to make proteins. The nitrogen cycle describes the ways in which nitrogen is recycled.

Carbon cycle

Most of the chemicals that make up living tissue contain carbon. When organisms die the carbon is recycled so that it can be used by future generations. The model that describes the processes involved is called the carbon cycle.

Steps in the carbon cycle

1. Carbon enters the atmosphere as carbon dioxide from respiration and combustion.
2. Carbon dioxide is absorbed by…