Decomposition – GCSE Biology B (Triple) OCR Revision

Decomposition is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts.
The process is largely carried out by decomposers, a broad group of organisms that includes bacteria and fungi.

Decomposers are extremely important as they break down dead plants and animals to simpler substances.
This breakdown releases nutrients back into the soil, which can then be used by plants in their growth and development.
Without decomposers, nutrients would be trapped in dead matter and unavailable for use by living organisms.

Decomposition begins with the process of decay. Bacteria and fungi (decomposers) secrete enzymes onto the dead material.
These enzymes break the substance down into smaller, soluble molecules, which the decomposers can then absorb and use.
This method of digestion, where the organism secretes enzymes onto the food to break it down, is called extracellular digestion.

Like any other biological process, the rate of decomposition is influenced by several factors such as temperature, oxygen levels and water availability.
A higher temperature generally increases the rate of decomposition, as it speeds up the metabolic activity of the decomposing organisms.
Decomposition is also faster in moist environments as many decomposers require a liquid environment to function effectively.
Oxygen is crucial for decomposition as many decomposers are aerobic organisms, meaning they need oxygen to live and function.

Decomposition plays a crucial role in nutrient cycles, recycling materials from dead organisms back into the environment.
It helps maintain the carbon cycle and the nitrogen cycle, which are crucial for sustaining life on Earth.
As plants absorb the nutrients released by decomposers, the process of decomposition links the biotic (living) and the abiotic (non-living) parts of the ecosystem.