Energy enters (most) ecosystems from the sun. The amount of energy that is available to each organism decreases along the food chain due to losses at each trophic level. When we describe energy as lost, it is never “used up” or destroyed, but only transformed into other (less useful) forms.
Ecosystems can exist in a state which is not constant but stable in a state of dynamic equilibrium, maintained by negative feedback mechanisms.
|1||Energy in an ecosystem|
|2||Positive and negative feedback|
|3||Equilibrium, resilience and tipping points|
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“Explain the factors that determine the resilience of an ecosystem and describe scenarios that could push an ecosystem beyond a tipping point.” [9 marks]
The essay should marked using the Paper 2, Section B essay markbands.