Review: Food Webs

L2 Decay and Recycling Organic Waste Learning Objectives: 1.Describe the process of decay and what organisms are responsible. 2.Explain the conditions needed for decay to happen. 3.Analyse why the process of decay is so important.

Decay Nutrients are taken in by plants and passed to consumers through the food chain. Where do the nutrients go next? Decay = process of decomposition, breaking down waste and dead plants and animals back into nutrients

The Decay Process Decomposers = group of organisms that break down waste and dead animals and plants Detritus feeders = type of decomposer, animals that starts the process of decay by eating waste and dead animal and plant remains (examples: maggots and some worms) Bacteria and fungi decomposers finish the job.

Decay = Recycling Nutrients Decomposers digest waste and dead plants and animals and release waste products; water, carbon dioxide, and mineral nutrients plants can absorb. Decay is an extremely important part of the ecosystem. Decomposers recycle nutrients back into the soil for plants, ensuring that there are enough nutrients to start the food chain again. Decomposers also remove organic waste, preventing the ecosystem from filling up with organic waste.

Conditions for Decay Warm conditions speed up the chemical reactions for decay. Too cold and it will be very slow (that’s why we use refrigerators) Too hot and the microorganisms (decomposers) will die Most microorganisms grow better in moist conditions. Access to oxygen is necessary as decomposers use respiration for energy.

Uses for Decomposition Sewage treatment plants use microorganisms to break down human waste so that it is safe to release back into environment. Compost heaps decompose plant material and food waste into nutrients that can be used as fertiliser for gardens.

Review: Carbon Cycle