Open and closed loop systems.

Open and closed loop systems.

What are they?
An open loop system or a linear system is a control system in which an input alters the output, but the output has no feedback loop and therefore no effect on the input. This means that they do not provide feedback of the actual state of the system in order to adjust the system.

An example of this is fossil fuels, natural resources are used much quicker than they are replaced so it's an non-feedback controller.

A closed loop system is an automatic control system operating on a feedback principle. They are ableto correct in order to meet target results. This means that feedback is provided in order to adjust the system.

A human example of this is the Maasai people which are a Tribe that live in Tanzania and Kenya. They rely on their animals for food and walk for many miles with their animals to find fresh food and water. They move around for more grass fortheir animals, their huts are made of natural materials, they eat wild plants and their bodies are left out for scavengers. They use no electricity

An animal example of this are barn owls; faeces are broken down by micro-organisms which become phosphates and nitrates in the soil which are taken up by plants. Young owls eat each other. Burying beetles lay eggs in flesh. Larvae eat fleash. Pellets slowly dissolve in the rain.

This diagram shows both systems.

There are many other closed-loop systems like;

Nitrifying bacteria (nitrogen cycle) 

1. Nitrogen gas is converted to nitrate compounds by nitrogen-fixing bacteriain soil or root nodules. Lightning also converts nitrogen gas to nitrate compounds. The Haber process converts nitrogen gas into ammonia used in fertilizers. Ammonia is converted to nitrates by nitrifying bacteria in the soil.
2. Plants absorb nitrates from the soil and use these to build up proteins. The plant may be eaten by an animal, and its biomass used to produce animal protein.
3. Urea and egested material is broken down by decomposers. This results in nitrogen being returned to the soil as ammonia.
4. Decomposers also break down the bodies of dead organisms resulting in nitrogen being returned to the soil as ammonia.
5. In some conditions denitrifying bacteria in the soil break down nitrates and return nitrogen to the air. This is usually in waterlogged soil. Improving drainage reduces this effect, making the soil more fertile.    

                                                       Water cycle;