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Define biodiversity.
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All Flashcards in Topic 1.9
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1.9.112 cards
Define biodiversity.
The **variety of life** in an area — including **species, habitat and genetic** diversity.
Define species richness.
The **number of different species** present in a community.
Define ecosystem stability.
The ability of an ecosystem to **keep functioning and recover** after a disturbance.
Name the three levels of biodiversity.
**Species** diversity, **habitat** diversity and **genetic** diversity.
Why does high biodiversity make an ecosystem more stable?
Species' roles **overlap**, so if one species is lost **another can cover its role** — the ecosystem keeps working.
Give two ways biodiversity is valuable to humans.
It provides **food and materials**, **medicines**, and **ecosystem services** (e.g. pollination, water cleaning).
What is an ecosystem service? Give an example.
Free 'work' an ecosystem does for us — e.g. **bees pollinating crops** or wetlands cleaning water.
Why is extinction such a serious loss?
It is **irreversible** — a species' genes and its ecological role are gone **forever**.
Name three human causes of biodiversity loss.
**Habitat destruction**, **overexploitation** and **pollution** (also invasive species and climate change).
What is the 'sixth mass extinction'?
The current **rapid, human-driven** loss of species, happening far faster than the natural background rate.
In a 'Suggest why biodiversity matters' question, what should you link to?
Link **more species** to a **benefit** — usually greater **stability / resilience** or more **ecosystem services**.
Why does just saying 'there are more species' score no marks?
You must **link** the extra species to a **consequence** (stability, services); the variety alone is not the mark.
1.9.212 cards
Define biodiversity.
The **variety of living organisms** — the number of different species and the variety within them.
Define extinction.
The **permanent loss** of a species when its **very last member dies**.
Name the five human causes of biodiversity loss.
**Habitat loss, overexploitation, pollution, invasive species, climate change** (memory hook: HIPPO).
Which cause destroys the most biodiversity, and why?
**Habitat loss** — clearing a habitat removes the home of **every** species that depends on it at once.
Define habitat loss.
Destruction or fragmentation of the **natural place a species lives** (e.g. deforestation, draining wetlands).
Define overexploitation.
Harvesting or hunting a species **faster than it can reproduce**, so its population crashes.
Define an invasive species.
A **non-native** species, introduced by humans, that spreads and **harms native species** by competing with, eating or infecting them.
Why are islands especially vulnerable to invasive species?
Native island species often have **no defences** against a brand-new predator or competitor.
Give one way pollution causes biodiversity loss.
Harmful substances such as **pesticides or plastic** added to air, water or soil **poison or kill** wildlife.
How does climate change cause biodiversity loss?
Human-driven warming **shifts conditions faster than species can adapt** (e.g. coral bleaching as the sea warms).
Difference between extinction and biodiversity loss?
**Extinction** = one whole species lost forever; **biodiversity loss** = the **wider fall** in variety, including shrinking populations.
What does a 'Discuss the impact' question need to score full marks?
**Named impacts with reasoning** (a direct and a knock-on effect) — not just 'it is bad'.
1.9.312 cards
Define in situ conservation.
Protecting a species **within its natural habitat** (e.g. in a nature reserve or national park).
Define ex situ conservation.
Protecting a species **outside its natural habitat** (e.g. in a zoo, botanic garden or seed bank).
Give two examples of in situ conservation.
**Nature reserves / national parks** and **wildlife corridors** that connect them.
State the main advantage of in situ conservation.
The **whole ecosystem** is conserved together, so the species keeps a large population with **high genetic diversity** and behaves naturally.
What is a wildlife corridor?
A protected strip of habitat that **connects two separate reserves** so animals can move between them.
How does a wildlife corridor help biodiversity?
It lets animals **move, interbreed and recolonise** between reserves — keeping populations larger and genetically diverse.
Define habitat fragmentation.
The breaking up of one large habitat into **smaller, separated patches**.
What is the edge effect?
The **harsher conditions** (wind, light, predators, invasive species) found **near the boundary** of a habitat patch compared with its interior.
Which reserve shape protects the most species, and why?
A **large, rounded** reserve — it has **more sheltered interior** and **less exposed edge**.
Why is a long, thin reserve poor at protecting species?
It is **almost all edge**, so harsh edge conditions reach every part and few interior species survive.
Why does in situ conservation keep genetic diversity high?
The wild population stays **large**, so a wide range of alleles is kept (unlike a small captive group).
Why is in situ often preferred over ex situ?
It conserves the **whole habitat/ecosystem** and lets the species **behave and evolve naturally**, not just survive in captivity.
1.9.412 cards
Define ex situ conservation.
Protecting a species **away from its natural habitat** — e.g. in a zoo, botanic garden, seed bank or gene bank.
Define in situ conservation.
Protecting a species **inside its natural habitat** — e.g. a nature reserve or national park.
Give three ex situ methods.
**Captive breeding** (zoos), **botanic gardens**, and **seed / gene banks**.
What is captive breeding?
Breeding endangered animals **under human care** to raise their numbers, often to **reintroduce** them to the wild.
What is a seed bank?
A cold, dry store of seeds from many species kept as a **long-term genetic back-up**.
How does ex situ help raise numbers?
Animals breed **safely** (away from predators/poachers) under expert care, so the **population grows**.
How do gene/seed banks help conservation?
They **preserve genetic variety** so a species can recover even if wild populations are lost.
What is reintroduction?
**Releasing** captive-bred individuals back into a (protected) **natural habitat**.
Give two limitations of ex situ conservation.
It is **expensive** and holds **small numbers** (inbreeding risk); it also **does not protect the habitat**.
Why can captive-bred animals struggle after release?
They may **lack survival skills** learned in the wild, so they can struggle to find food or avoid predators.
Why is ex situ called a 'back-up'?
It keeps a species alive when its **wild habitat is too damaged**, but it does not protect that habitat — so it works **best alongside in situ**.
In situ vs ex situ — one key difference?
**In situ protects the habitat** (the species stays in the wild); **ex situ does not** (the species is held off-site).
1.9.512 cards
Define rewilding.
Restoring the **natural processes** of a degraded ecosystem so it becomes **self-sustaining**, often by reintroducing a **keystone species**.
Define a keystone species.
A species whose effect on its ecosystem is **far larger than its numbers** suggest (e.g. a top predator or a beaver).
Define a degraded ecosystem.
An ecosystem that has been **damaged** so it works less well (e.g. a cleared forest or drained wetland).
What is the flagship method of rewilding?
Reintroducing a **keystone species** to restart natural processes across the ecosystem.
Name a rewilding method that is NOT a keystone reintroduction.
Restore natural **water flow** (re-flooding), re-establish natural **grazing**, let **native plants** return, or reconnect habitats with **corridors**.
How does rewilding differ from ordinary conservation?
Conservation protects species and often needs **ongoing management**; rewilding restores **natural processes** so the ecosystem **manages itself**.
Why can reintroducing one keystone species restore a whole ecosystem?
Its activity (e.g. damming or predation) restarts a **chain** of natural processes that many other species depend on.
Give an example of a keystone reintroduction in rewilding.
**Beavers** — they build dams that restore water flow and create wetland that supports many species.
What does 'ecosystem restoration' mean?
Repairing a **damaged** ecosystem so its **natural processes** and **biodiversity** recover.
How does rewilding help minimise biodiversity loss?
By restoring natural processes in a **degraded** ecosystem, it **reverses** damage so more species can return.
Name two natural processes rewilding tries to restore.
Any two of: **grazing**, **predation**, **flooding/water flow**, **seed dispersal**.
In a 'rewilding methods other than keystone reintroduction' question, what must each method do?
Restore a **natural process** (not just add a species) — e.g. re-flooding or letting native plants return.
1.9.612 cards
What does EDGE stand for?
**Evolutionarily Distinct and Globally Endangered**.
What is the purpose of the EDGE programme?
To **prioritise** which species to conserve — choosing those that are both distinct and endangered when resources are limited.
Define 'evolutionarily distinct'.
Having **very few close living relatives** — a unique, long branch on the tree of life carrying unique evolutionary history.
Define 'globally endangered'.
At **high risk of extinction worldwide** (e.g. a very small or fast-falling population).
What is an EDGE species?
A species that is **both** highly evolutionarily distinct **and** globally endangered — so it is high priority for conservation.
Why must conservationists prioritise species?
There are **more endangered species than money, land and time** to save them all, so choices must be made.
A species is distinct but common. Is it a high EDGE priority?
**No** — it is distinct but not at risk, so it is not urgent.
A species is endangered but has many close relatives. High EDGE priority?
**No (lower)** — its loss is a smaller loss to the tree of life because similar species remain.
Why is losing an evolutionarily distinct species so costly?
It removes a **unique branch of the tree of life and unique genes** that **no other species can replace**.
Define biodiversity.
The **variety of life** — the range of different species (and genes and ecosystems) in an area.
Define conservation.
**Protecting species and habitats** so that biodiversity is maintained for the future.
Which TWO criteria must a top EDGE species meet?
It must be **evolutionarily distinct AND globally endangered** — high on both, not just one.
Topic 1.9 study notes
Full notes & explanations for Conservation of biodiversity
Biology exam skills
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