Sustainability, mesocosms and biomagnification
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Flip to reveal answersWhat does 'sustainability' mean for harvesting a resource?
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Question
What does 'sustainability' mean for harvesting a resource?
Answer
Using it so it lasts indefinitely — taking **no more than is naturally replaced**, so the stock is not depleted.
Question
When is a harvest unsustainable?
Answer
When **more is removed than is replaced** each year — the stock declines and can **collapse**.
Question
What is a mesocosm?
Answer
A **small, enclosed experimental ecosystem** (e.g. a sealed tank or fenced plot) used to study how an ecosystem behaves.
Question
Give one strength and one limitation of a mesocosm.
Answer
Strength: **controlled, cheap, repeatable and safe/ethical**. Limitation: **small and simplified**, so it may not match a real ecosystem.
Question
Define biomagnification.
Answer
The **increase in a persistent pollutant's concentration at each higher trophic level** of a food chain.
Question
Why does a pollutant biomagnify up a food chain?
Answer
It is **persistent** (not broken down or excreted), and each predator **eats many prey**, so it keeps all of their pollutant and the concentration multiplies up the chain.
Question
Which organism is worst affected by biomagnification?
Answer
The **top predator** — it has the **highest** concentration of the pollutant.
Question
How is biomagnification different from bioaccumulation?
Answer
**Bioaccumulation** = build-up within **one organism** over its life. **Biomagnification** = increase **up the food chain**, level by level.
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Topic 4.11 hub
Stability and change
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