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Dynamic Equilibrium |
 Dynamic Equilibrium, Negative Feedback and Positive Feedback Worksheet |
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A system can be defined as any set of interrelated components or objects which are connected together to form a working unit or unified whole. In geography it is usual to recognise two general types of systems: closed and open. |
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| Dynamic Equilibrium |
This diagram shows interrelationships between components of an ecosystem.
Exam Question Practice With reference to the above diagram, discuss the concept of dynamic equilibrium. [4 marks] |
| When an ecosystem is in balance - it is in steady state or dynamic equilibrium. Self-regulation archives this. As an ecosystem is a system - change in one component will affect other components, which in term could continue to change the first component. |
| Positive and Negative Feedback |
Feedback Systems | Source |
Negative and positive feedback systems keep an ecosystem in dynamic equilibrium. A negative feedback decreases the amount of change by reducing some of the inputs, returning the ecosystem to stability. Positive feedback is less common. It increases the amount of change. This leads to an imbalance. Negative Feedback Example: A good supply of grass for rabbits to eat will attract more rabbits to the area, which puts pressure on the grass, so it dies back, so the decreased food supply leads to a decrease in population because of death or out migration, which takes away the pressure on the grass, which leads to more growth and a good supply of food which leads to a more rabbits attracted to the area which puts pressure on the grass and so on and on.... Positive Feedback Example: If a pond ecosystem became polluted with nitrates, washed off agricultural land by surface runoff, algae would rapidly grow in the pond. The amount of dissolved oxygen in the water would decrease, killing the fish. The decomposers that would increase due to the dead fish would further decrease the amount of dissolved oxygen and so on... |
| Exam Practice Question Explain what is meant by negative and positive feedback and then, with
reference to one or more ecosystems of your choice, give a detailed
account of how these processes affect the stability of the chosen
system(s).
[20 marks] |
Credits: The inspiration for this resource came from Jodi John - British School Manila. |
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