Causes of biodiversity loss and extinction
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Question
Define biodiversity.
Answer
The **variety of living organisms** — the number of different species and the variety within them.
Question
Define extinction.
Answer
The **permanent loss** of a species when its **very last member dies**.
Question
Name the five human causes of biodiversity loss.
Answer
**Habitat loss, overexploitation, pollution, invasive species, climate change** (memory hook: HIPPO).
Question
Which cause destroys the most biodiversity, and why?
Answer
**Habitat loss** — clearing a habitat removes the home of **every** species that depends on it at once.
Question
Define habitat loss.
Answer
Destruction or fragmentation of the **natural place a species lives** (e.g. deforestation, draining wetlands).
Question
Define overexploitation.
Answer
Harvesting or hunting a species **faster than it can reproduce**, so its population crashes.
Question
Define an invasive species.
Answer
A **non-native** species, introduced by humans, that spreads and **harms native species** by competing with, eating or infecting them.
Question
Why are islands especially vulnerable to invasive species?
Answer
Native island species often have **no defences** against a brand-new predator or competitor.
Question
Give one way pollution causes biodiversity loss.
Answer
Harmful substances such as **pesticides or plastic** added to air, water or soil **poison or kill** wildlife.
Question
How does climate change cause biodiversity loss?
Answer
Human-driven warming **shifts conditions faster than species can adapt** (e.g. coral bleaching as the sea warms).
Question
Difference between extinction and biodiversity loss?
Answer
**Extinction** = one whole species lost forever; **biodiversity loss** = the **wider fall** in variety, including shrinking populations.
Question
What does a 'Discuss the impact' question need to score full marks?
Answer
**Named impacts with reasoning** (a direct and a knock-on effect) — not just 'it is bad'.
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Topic 1.9 hub
Conservation of biodiversity
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