Facts At Your Fingertips: The living world – Cycles
Every living thing needs the elements oxygen and carbon to grow and make energy.
These elements are constantly passing from the air into living things and back into the air again in cycles that are essential to life.
The oxygen cycle
Plants release oxygen into the air and absorb carbon dioxide from the air during photosynthesis, which occurs only during the day. Both animals and plants use the oxygen in air to release energy in their bodies during a process called respiration.
Respiration takes place all the time and produces carbon dioxide, which is released into the air to be absorbed by plants during photosynthesis as the cycle is repeated.
Animals breathe in oxygen and breathe out carbon dioxide all the time as they respire
Plants take in carbon dioxide and give out oxygen during photosynthesis
Plants take in oxygen and give out carbon dioxide all the time as they respire
The carbon cycle
Carbon is taken in by living things in their food. It is released into the atmosphere during respiration and also when plants and animals die and decay.
During photosynthesis, plants absorb carbon dioxide from the atmosphere so they can grow; the plants will then become new food for other living things.
Plants and animals die and their bodies decay
Decomposers, such as worms, bacteria, and fungi, give out carbon dioxide as they feed and respire
Carbon dioxide in the atmosphere
Plants take in carbon dioxide during photosynthesis
Plants give out carbon dioxide during respiration
Animals eat plants and take in some carbon
Animals breathe out carbon dioxide and their dung also contains carbon