State in brief the role of photosynthesis and respiration in carbon cycle.
The global carbon cycle connects all living things together, and has profound effects on global climate. Every year billions of tonnes of carbon are exchanged between the atmosphere, plants, soils and the ocean. These exchanges are largely driven by the activity of plants and soil microbes, through the processes of photosynthesis and respiration.
Photosynthesis is the process whereby plants use sunlight to convert atmospheric carbon dioxide into organic compounds, such as sugars and starches. All the food we eat is produced by or dependent on photosynthesis, and photosynthesis also provides us with wood, fibres and other plant products.
Respiration is the process whereby living things use organic compounds to support their metabolism, and is found in all living things. Respiration releases carbon dioxide to the atmosphere. The respiration of multi-celled animals is not a significant part of the carbon cycle; vegetation and microbes the most important biological components. Microbes decompose plant litter and dead wood in the soil, and, via respiration, return billions of tonnes of carbon to the atmosphere each year.