GCSE Biology revision

Extinction

The development of understanding of genetics and evolution

AQA 4.1.1.1

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AQA student objectives

Learning pathway

All · Most · Some

ALL 🎯

Identify and describe What is Extinction?, Human Population Growth and Habitat Destruction and Invasive and Introduced Species in the context of extinction.

MOST 🎯🎯

Explain the relationships between What is Extinction?, Human Population Growth and Habitat Destruction and Invasive and Introduced Species and how they contribute to extinction.

SOME 🎯🎯🎯

Apply and analyse knowledge of What is Extinction?, Human Population Growth and Habitat Destruction and Invasive and Introduced Species to interpret unfamiliar information about extinction.

Revision summary

Key knowledge

Read on screen, then print for Cornell-style active revision.

What is Extinction?

Extinction occurs when there are no remaining individuals of a species still alive anywhere on Earth.
Species that are not well adapted to their environment are less likely to survive and reproduce, making them more vulnerable to extinction.
The kakapo, a flightless bird from New Zealand, is an example of a poorly adapted animal struggling to survive against introduced predators such as domestic cats.

1. What is Extinction?AQA

Notes

Extinction occurs when there are no remaining individuals of a species still alive anywhere on Earth.
Species that are not well adapted to their environment are less likely to survive and reproduce, making them more vulnerable to extinction.
The kakapo, a flightless bird from New Zealand, is an example of a poorly adapted animal struggling to survive against introduced predators such as domestic cats.

Human Population Growth and Habitat Destruction

As the human population increases, it puts greater pressure on natural environments, causing the rate of extinctions to rise.
Deforestation and the construction of human settlements reduce and destroy natural habitats, leaving species with nowhere to live or feed.
Human impact on the environment often speeds up the rate at which species become extinct.

2. Human Population Growth and Habitat DestructionAQA

Notes

As the human population increases, it puts greater pressure on natural environments, causing the rate of extinctions to rise.
Deforestation and the construction of human settlements reduce and destroy natural habitats, leaving species with nowhere to live or feed.
Human impact on the environment often speeds up the rate at which species become extinct.

Invasive and Introduced Species

The movement of species around the globe by humans can lead to extinctions when newly introduced species hunt or outcompete existing ones.
Outcompeting means being more successful than another species when competing for the same resources in the same environment.
The red fox is considered one of the world's worst invasive species, particularly in countries like Australia, where it threatens native wildlife.

3. Invasive and Introduced SpeciesAQA

Notes

The movement of species around the globe by humans can lead to extinctions when newly introduced species hunt or outcompete existing ones.
Outcompeting means being more successful than another species when competing for the same resources in the same environment.
The red fox is considered one of the world's worst invasive species, particularly in countries like Australia, where it threatens native wildlife.

Disease as a Cause of Extinction

New diseases can cause extinctions, either by evolving naturally over time or by being introduced to new regions by humans.
Species with no prior exposure to a disease may have no immunity, making them extremely vulnerable to population collapse.

Natural and Climate-Related Causes

Extinctions can also occur due to slow, natural changes in the environment to which species cannot adapt quickly enough.
Climate change can alter habitats and food availability, leading to conditions that result in the extinction of species.

Exam Technique: Understanding the Command Word

When a question uses the command word 'suggest', you are expected to apply your biological knowledge to an unfamiliar situation.
You are not expected to know specific details about an unfamiliar species; instead, use the information provided alongside your existing knowledge.
Always read the question carefully to identify what topic it relates to — in extinction questions, consider human impact and the animal's adaptations.

6. Exam Technique: Understanding the Command WordAQA

Notes

When a question uses the command word 'suggest', you are expected to apply your biological knowledge to an unfamiliar situation.
You are not expected to know specific details about an unfamiliar species; instead, use the information provided alongside your existing knowledge.
Always read the question carefully to identify what topic it relates to — in extinction questions, consider human impact and the animal's adaptations.

Exam Technique: Structuring Your Answer

Start by stating that the arrival of Europeans would have increased the human population in the region.
Link population growth to specific impacts such as deforestation or building, which may have destroyed the species' natural habitat.
Also consider that introduced species may have hunted or outcompeted the native animal, and that new diseases brought by humans may have contributed to its extinction.

7. Exam Technique: Structuring Your AnswerAQA

Notes

Start by stating that the arrival of Europeans would have increased the human population in the region.
Link population growth to specific impacts such as deforestation or building, which may have destroyed the species' natural habitat.
Also consider that introduced species may have hunted or outcompeted the native animal, and that new diseases brought by humans may have contributed to its extinction.