Back to Topic 3.2 — Human impact on biodiversity

3.2.1ESS58 flashcards

Threats to biodiversity

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3.2.1

Question

State the core meaning of overexploitation in one phrase.

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All 58 Flashcards — Threats to biodiversity

Card 1concept

Question

State the core meaning of overexploitation in one phrase.

Answer

Overexploitation means unsustainable use: take more than can be replaced.

💡 Hint

Unsustainable use

Card 2example

Question

What is the difference between direct and indirect threats?

Answer

Direct threats target species directly (e.g., poaching), whereas indirect threats damage ecosystems as a side effect (e.g., habitat loss, climate change).

💡 Hint

Direct = species; indirect = habitat/system.

Card 3example

Question

What is an invasive species?

Answer

An invasive species is a non-native organism introduced by humans that spreads rapidly and harms native ecosystems.

💡 Hint

Non-native + harmful.

Card 4example

Question

What is the tragedy of the commons?

Answer

It occurs when individuals overuse a shared resource for short-term gain, leading to long-term depletion and collective loss.

💡 Hint

Shared resource overused.

Card 5example

Question

What is the main driver of biodiversity loss today?

Answer

Human activity is the main driver, including habitat destruction, overexploitation, pollution, and climate change.

💡 Hint

Mostly human causes.

Card 6example

Question

List four major human threats to biodiversity.

Answer

Habitat loss, overexploitation, pollution, climate change, and invasive species are major threats.

💡 Hint

Think HIPPO + climate.

Card 7definition

Question

Define habitat destruction.

Answer

Habitat destruction is the removal or severe damage of a habitat so it can no longer support its original species.

💡 Hint

Removal/damage so habitat cannot support original species

Card 8definition

Question

Define habitat fragmentation.

Answer

Habitat fragmentation is when one large habitat is broken into smaller, isolated patches. The habitat still exists, but populations become separated.

💡 Hint

Large habitat split into isolated patches

Card 9concept

Question

Distinguish between habitat destruction and fragmentation.

Answer

Destruction removes the habitat completely or makes it unusable. Fragmentation splits habitat into smaller, isolated patches.

💡 Hint

Destruction = remove; Fragmentation = split

Card 10definition

Question

Define overexploitation.

Answer

Overexploitation is using a natural resource faster than it can be replaced by reproduction or regrowth.

💡 Hint

Use > replace

Card 11concept

Question

Give an example of overexploitation in fisheries.

Answer

Overfishing can cause stock collapse and alter food webs, e.g. Atlantic cod declined dramatically due to heavy fishing.

💡 Hint

Named example: Atlantic cod

Card 12concept

Question

State one cause of habitat destruction.

Answer

Examples include deforestation for agriculture, draining wetlands for development, and clearing grassland for crops.

💡 Hint

Name one cause: deforestation, draining wetlands, clearing grassland

Card 13example

Question

How does habitat loss threaten species?

Answer

Habitat loss reduces available food, shelter, and breeding space, causing population decline and increased extinction risk.

💡 Hint

Less space + fewer resources.

Card 14example

Question

Why does the tragedy of the commons occur?

Answer

Because individuals act in their own short-term interest while the costs of overuse are shared by everyone.

💡 Hint

Short-term gain vs shared loss.

Card 15concept

Question

Explain how poaching can rapidly reduce populations.

Answer

Poaching often removes breeding adults, so birth rates fall and populations decline quickly.

💡 Hint

Remove breeders → rapid decline

Card 16example

Question

Why are invasive species often successful in new environments?

Answer

They may lack natural predators, compete strongly for resources, or reproduce quickly in the new ecosystem.

💡 Hint

Few predators + strong competition.

Card 17example

Question

Give two examples of direct threats to biodiversity.

Answer

Overharvesting and poaching are direct threats because they remove individuals from populations.

💡 Hint

Target the species.

Card 18concept

Question

Give two examples of overexploitation.

Answer

Overfishing, poaching, and logging of old-growth forests are common examples.

💡 Hint

Any two: overfishing/poaching/logging

Card 19concept

Question

Explain how overexploitation disrupts energy transfer between trophic levels.

Answer

Removing organisms faster than they can be replaced breaks feeding links, reduces prey availability, and can trigger trophic cascades.

💡 Hint

Removes key links

Card 20concept

Question

State one consequence of fragmentation for populations.

Answer

Fragmentation creates smaller, isolated populations, increasing extinction risk and making it harder to find mates.

💡 Hint

Small + isolated populations

Card 21concept

Question

State two edge effects.

Answer

Edges are often hotter and windier (and can be drier), and may have more predators or invasive species.

💡 Hint

Hotter/windier + more predators/invasives

Card 22concept

Question

Explain why overexploitation can cause population collapse.

Answer

If removal exceeds reproduction, population size declines. Once numbers drop too low, recovery becomes difficult.

💡 Hint

Removal > reproduction

Card 23example

Question

Why are invasive species especially damaging?

Answer

They disrupt ecosystem balance by outcompeting native species and altering food webs.

💡 Hint

Disrupt balance.

Card 24concept

Question

Explain why fragmentation can reduce genetic diversity.

Answer

Isolation reduces gene flow. Smaller populations are more likely to inbreed, lowering genetic diversity and adaptability.

💡 Hint

Less gene flow → more inbreeding → lower diversity

Card 25example

Question

Why do unmanaged shared resources often decline?

Answer

Because without regulation, individuals maximise personal benefit, leading to overuse and depletion.

💡 Hint

No rules = overuse.

Card 26definition

Question

Define biodiversity.

Answer

Biodiversity is the variety of life, including diversity of species, habitats, and genetic diversity within species.

💡 Hint

Species + habitat + genetic

Card 27concept

Question

Explain how habitat destruction affects food webs.

Answer

It removes producers and habitat, so less energy enters the food web and fewer consumers can be supported, reducing stability.

💡 Hint

Removes producers → less energy entry → fewer consumers

Card 28concept

Question

Explain why overexploitation reduces ecosystem resilience.

Answer

Fewer individuals and species remain, so the ecosystem has less functional diversity and recovers less well after disturbance.

💡 Hint

Less diversity → lower resilience

Card 29concept

Question

State why fragmentation increases extinction risk.

Answer

Smaller, isolated populations have fewer mates, lower gene flow, and are more vulnerable to random events.

💡 Hint

Small + isolated = vulnerable

Card 30concept

Question

Explain how overexploitation affects food webs.

Answer

Removing organisms breaks feeding links, reduces energy transfer, and can trigger trophic cascades.

💡 Hint

Break links → trophic cascades

Card 31concept

Question

Explain one ecosystem impact of overfishing.

Answer

Removing top predators or key species can cause trophic cascades and change community structure.

💡 Hint

Trophic cascade

Card 32example

Question

Give two examples of indirect threats to biodiversity.

Answer

Habitat loss and climate change are indirect threats because they alter ecosystems and affect many species at once.

💡 Hint

System-level impacts.

Card 33example

Question

How can invasive species reduce native biodiversity?

Answer

They outcompete, prey on, or bring diseases to native species, causing population declines or extinctions.

💡 Hint

Competition + predation + disease.

Card 34example

Question

Give one biodiversity-related example of the tragedy of the commons.

Answer

Overfishing in open oceans where no single country controls the resource can lead to stock collapse.

💡 Hint

Open-access overuse.

Card 35example

Question

Why are small populations more vulnerable to extinction?

Answer

Small populations have lower genetic diversity, are more affected by random events, and may struggle to reproduce successfully.

💡 Hint

Small size = high risk.

Card 36definition

Question

Define edge effects and give one example.

Answer

Edge effects are changes at habitat boundaries, such as higher temperature and wind, lower humidity, and more predators or invasive species.

💡 Hint

Edges are hotter/drier/windier + more predators/invasives

Card 37concept

Question

Distinguish between direct and indirect human impacts on food webs.

Answer

Direct impacts remove organisms or energy entry (e.g., habitat loss, overharvesting, pollution); indirect impacts change conditions or interactions (e.g., invasive species, climate change).

💡 Hint

Remove vs change conditions

Card 38example

Question

Why do combined impacts increase collapse risk?

Answer

Multiple interacting threats reduce resilience and make ecosystems less able to recover.

💡 Hint

Stacked pressures.

Card 39example

Question

Why can invasive predators have strong ecosystem effects?

Answer

Without natural enemies, invasive predators can rapidly reduce prey populations and disrupt entire food webs.

💡 Hint

No natural control.

Card 40example

Question

Give one example of a direct human threat to a species.

Answer

Poaching or overharvesting directly reduces population size and can push species toward extinction.

💡 Hint

Directly targets species.

Card 41example

Question

Why do indirect threats often affect many species at once?

Answer

Because they change habitat conditions or ecosystem processes that multiple species depend on.

💡 Hint

Shared habitat impact.

Card 42concept

Question

State two biodiversity impacts of habitat destruction.

Answer

It reduces species richness and can cause local extinctions as populations lose space, food, and shelter.

💡 Hint

Less habitat → fewer species + higher extinction risk

Card 43concept

Question

State one management method that makes exploitation more sustainable.

Answer

Use quotas or regulated harvesting so removal stays below replacement rate.

💡 Hint

Keep removal below replacement

Card 44concept

Question

State one way to reduce edge effects in reserves.

Answer

Use buffer zones or increase reserve size to reduce the proportion of habitat near edges.

💡 Hint

Bigger area + buffers = fewer edges

Card 45example

Question

How can management reduce the tragedy of the commons?

Answer

By introducing regulations, quotas, enforcement, or shared agreements that limit overuse and promote sustainability.

💡 Hint

Rules + enforcement.

Card 46concept

Question

State one sign that a resource is being overexploited.

Answer

Declining population size or catch per unit effort (more effort needed to get the same catch).

💡 Hint

Falling population / lower catch per effort

Card 47concept

Question

Explain how logging can be overexploitation.

Answer

Old-growth forests may be cut faster than they regrow, reducing habitat and biodiversity for decades.

💡 Hint

Cut > regrow

Card 48concept

Question

State one solution to habitat fragmentation.

Answer

Wildlife corridors connect isolated patches, allowing movement, gene flow, and breeding between populations.

💡 Hint

Wildlife corridors reconnect patches

Card 49example

Question

Why are invasive species considered both a direct and indirect threat?

Answer

They directly harm native species but also indirectly alter ecosystem structure and processes.

💡 Hint

Species-level + ecosystem-level effects.

Card 50concept

Question

State one solution to overexploitation.

Answer

Sustainable management such as quotas, seasonal bans, protected areas, or selective gear reduces removal rates.

💡 Hint

Quotas/bans/protected areas/selective gear

Card 51example

Question

Exam link: why is early intervention important in biodiversity protection?

Answer

Because preventing decline is easier and cheaper than restoring ecosystems after severe damage or species extinction.

💡 Hint

Prevention > restoration.

Card 52example

Question

Why do multiple combined threats reduce ecosystem resilience?

Answer

When several pressures act at once (e.g., habitat loss plus climate change), recovery is harder and tipping points are more likely.

💡 Hint

Multiple stresses amplify risk.

Card 53concept

Question

State the key linking phrase for fragmentation questions.

Answer

Fragmentation reduces gene flow and increases edge effects, which lowers population viability and biodiversity.

💡 Hint

Gene flow down + edge effects up

Card 54concept

Question

State the biodiversity link to include in exam answers on overexploitation.

Answer

Overexploitation reduces population sizes, which can reduce species richness and lower ecosystem resilience.

💡 Hint

Fewer individuals → lower biodiversity/resilience

Card 55concept

Question

Give a named example of habitat destruction.

Answer

Amazon rainforest cleared for cattle ranching removes habitat for many species and reduces ecosystem resilience.

💡 Hint

Named example: Amazon cleared for cattle ranching

Card 56concept

Question

State one exam-ready cause → effect chain for overexploitation.

Answer

Overexploitation removes organisms faster than they reproduce, reducing population size and disrupting energy transfer in food webs.

💡 Hint

Take > reproduce → population down → food web disrupted

Card 57example

Question

Why does habitat fragmentation reduce resilience?

Answer

Fragmentation isolates populations, limits gene flow, increases edge effects, and reduces overall ecosystem stability.

💡 Hint

Isolation + edge effects.

Card 58example

Question

Exam tip: in a 4-mark “explain a threat” question, what should you include?

Answer

Name the threat, describe how it affects species or habitats, and explain the consequences for population size or ecosystem stability.

💡 Hint

Name + mechanism + consequence.

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Human impact on biodiversity

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