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List four major human threats to biodiversity.
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3.3.150 cards
List four major human threats to biodiversity.
Habitat loss, overexploitation, pollution, climate change, and invasive species are major threats.
Think HIPPO + climate.
List four major human threats to biodiversity.
Habitat loss, overexploitation, pollution, climate change, and invasive species are major threats.
Think HIPPO + climate.
What is an invasive species?
An invasive species is a non-native organism introduced by humans that spreads rapidly and harms native ecosystems.
Non-native + harmful.
What is the difference between direct and indirect threats?
Direct threats target species directly (e.g., poaching), whereas indirect threats damage ecosystems as a side effect (e.g., habitat loss, climate change).
Direct = species; indirect = habitat/system.
What is an invasive species?
An invasive species is a non-native organism introduced by humans that spreads rapidly and harms native ecosystems.
Non-native + harmful.
What is the main driver of biodiversity loss today?
Human activity is the main driver, including habitat destruction, overexploitation, pollution, and climate change.
Mostly human causes.
What is the tragedy of the commons?
It occurs when individuals overuse a shared resource for short-term gain, leading to long-term depletion and collective loss.
Shared resource overused.
What is the difference between direct and indirect threats?
Direct threats target species directly (e.g., poaching), whereas indirect threats damage ecosystems as a side effect (e.g., habitat loss, climate change).
Direct = species; indirect = habitat/system.
What is the main driver of biodiversity loss today?
Human activity is the main driver, including habitat destruction, overexploitation, pollution, and climate change.
Mostly human causes.
What is the tragedy of the commons?
It occurs when individuals overuse a shared resource for short-term gain, leading to long-term depletion and collective loss.
Shared resource overused.
How does habitat loss threaten species?
Habitat loss reduces available food, shelter, and breeding space, causing population decline and increased extinction risk.
Less space + fewer resources.
Why are invasive species especially damaging?
They disrupt ecosystem balance by outcompeting native species and altering food webs.
Disrupt balance.
Why are invasive species especially damaging?
They disrupt ecosystem balance by outcompeting native species and altering food webs.
Disrupt balance.
Why does the tragedy of the commons occur?
Because individuals act in their own short-term interest while the costs of overuse are shared by everyone.
Short-term gain vs shared loss.
Give two examples of direct threats to biodiversity.
Overharvesting and poaching are direct threats because they remove individuals from populations.
Target the species.
Why does the tragedy of the commons occur?
Because individuals act in their own short-term interest while the costs of overuse are shared by everyone.
Short-term gain vs shared loss.
Why are invasive species often successful in new environments?
They may lack natural predators, compete strongly for resources, or reproduce quickly in the new ecosystem.
Few predators + strong competition.
Why are invasive species often successful in new environments?
They may lack natural predators, compete strongly for resources, or reproduce quickly in the new ecosystem.
Few predators + strong competition.
Give two examples of direct threats to biodiversity.
Overharvesting and poaching are direct threats because they remove individuals from populations.
Target the species.
How does habitat loss threaten species?
Habitat loss reduces available food, shelter, and breeding space, causing population decline and increased extinction risk.
Less space + fewer resources.
Why do unmanaged shared resources often decline?
Because without regulation, individuals maximise personal benefit, leading to overuse and depletion.
No rules = overuse.
Give two examples of indirect threats to biodiversity.
Habitat loss and climate change are indirect threats because they alter ecosystems and affect many species at once.
System-level impacts.
How can invasive species reduce native biodiversity?
They outcompete, prey on, or bring diseases to native species, causing population declines or extinctions.
Competition + predation + disease.
Give one biodiversity-related example of the tragedy of the commons.
Overfishing in open oceans where no single country controls the resource can lead to stock collapse.
Open-access overuse.
Why are small populations more vulnerable to extinction?
Small populations have lower genetic diversity, are more affected by random events, and may struggle to reproduce successfully.
Small size = high risk.
Why do unmanaged shared resources often decline?
Because without regulation, individuals maximise personal benefit, leading to overuse and depletion.
No rules = overuse.
Give two examples of indirect threats to biodiversity.
Habitat loss and climate change are indirect threats because they alter ecosystems and affect many species at once.
System-level impacts.
How can invasive species reduce native biodiversity?
They outcompete, prey on, or bring diseases to native species, causing population declines or extinctions.
Competition + predation + disease.
Give one biodiversity-related example of the tragedy of the commons.
Overfishing in open oceans where no single country controls the resource can lead to stock collapse.
Open-access overuse.
Why are small populations more vulnerable to extinction?
Small populations have lower genetic diversity, are more affected by random events, and may struggle to reproduce successfully.
Small size = high risk.
Why do indirect threats often affect many species at once?
Because they change habitat conditions or ecosystem processes that multiple species depend on.
Shared habitat impact.
How can management reduce the tragedy of the commons?
By introducing regulations, quotas, enforcement, or shared agreements that limit overuse and promote sustainability.
Rules + enforcement.
Give one example of a direct human threat to a species.
Poaching or overharvesting directly reduces population size and can push species toward extinction.
Directly targets species.
Give one example of a direct human threat to a species.
Poaching or overharvesting directly reduces population size and can push species toward extinction.
Directly targets species.
Why do combined impacts increase collapse risk?
Multiple interacting threats reduce resilience and make ecosystems less able to recover.
Stacked pressures.
Why can invasive predators have strong ecosystem effects?
Without natural enemies, invasive predators can rapidly reduce prey populations and disrupt entire food webs.
No natural control.
Why do combined impacts increase collapse risk?
Multiple interacting threats reduce resilience and make ecosystems less able to recover.
Stacked pressures.
Why do indirect threats often affect many species at once?
Because they change habitat conditions or ecosystem processes that multiple species depend on.
Shared habitat impact.
How can management reduce the tragedy of the commons?
By introducing regulations, quotas, enforcement, or shared agreements that limit overuse and promote sustainability.
Rules + enforcement.
Why can invasive predators have strong ecosystem effects?
Without natural enemies, invasive predators can rapidly reduce prey populations and disrupt entire food webs.
No natural control.
Why does habitat fragmentation reduce resilience?
Fragmentation isolates populations, limits gene flow, increases edge effects, and reduces overall ecosystem stability.
Isolation + edge effects.
Exam link: why is early intervention important in biodiversity protection?
Because preventing decline is easier and cheaper than restoring ecosystems after severe damage or species extinction.
Prevention > restoration.
Exam tip: in a 4-mark “explain a threat” question, what should you include?
Name the threat, describe how it affects species or habitats, and explain the consequences for population size or ecosystem stability.
Name + mechanism + consequence.
Why do multiple combined threats reduce ecosystem resilience?
When several pressures act at once (e.g., habitat loss plus climate change), recovery is harder and tipping points are more likely.
Multiple stresses amplify risk.
Why are invasive species considered both a direct and indirect threat?
They directly harm native species but also indirectly alter ecosystem structure and processes.
Species-level + ecosystem-level effects.
Why are invasive species considered both a direct and indirect threat?
They directly harm native species but also indirectly alter ecosystem structure and processes.
Species-level + ecosystem-level effects.
Why do multiple combined threats reduce ecosystem resilience?
When several pressures act at once (e.g., habitat loss plus climate change), recovery is harder and tipping points are more likely.
Multiple stresses amplify risk.
Exam tip: in a 4-mark “explain a threat” question, what should you include?
Name the threat, describe how it affects species or habitats, and explain the consequences for population size or ecosystem stability.
Name + mechanism + consequence.
Why does habitat fragmentation reduce resilience?
Fragmentation isolates populations, limits gene flow, increases edge effects, and reduces overall ecosystem stability.
Isolation + edge effects.
Exam link: why is early intervention important in biodiversity protection?
Because preventing decline is easier and cheaper than restoring ecosystems after severe damage or species extinction.
Prevention > restoration.
3.3.210 cards
What does “conservation status” mean?
Conservation status describes how close a species is to extinction and how urgently it needs protection.
Risk of extinction.
What does “conservation status” mean?
Conservation status describes how close a species is to extinction and how urgently it needs protection.
Risk of extinction.
Which organisation publishes the global conservation status system used worldwide?
The International Union for Conservation of Nature (IUCN) publishes the IUCN Red List categories.
IUCN Red List.
Which organisation publishes the global conservation status system used worldwide?
The International Union for Conservation of Nature (IUCN) publishes the IUCN Red List categories.
IUCN Red List.
Name two factors the IUCN uses to assess extinction risk.
Population size, population trend (increasing/decreasing), geographic range, and known threats are key factors.
Size + trend + range + threats.
Name two factors the IUCN uses to assess extinction risk.
Population size, population trend (increasing/decreasing), geographic range, and known threats are key factors.
Size + trend + range + threats.
Put these IUCN categories in order from lower to higher extinction risk: NT, VU, EN, CR.
Near Threatened (NT) → Vulnerable (VU) → Endangered (EN) → Critically Endangered (CR).
NT < VU < EN < CR.
Put these IUCN categories in order from lower to higher extinction risk: NT, VU, EN, CR.
Near Threatened (NT) → Vulnerable (VU) → Endangered (EN) → Critically Endangered (CR).
NT < VU < EN < CR.
Why is conservation status useful for conservation decisions?
It helps prioritise action and funding by showing which species are most at risk and need urgent protection.
Priorities + funding.
Why is conservation status useful for conservation decisions?
It helps prioritise action and funding by showing which species are most at risk and need urgent protection.
Priorities + funding.
Topic 3.3 study notes
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