Impact of environmental change (biology only) (HT only) — AQA GCSE Biology
Test yourself on Impact of environmental change (biology only) (HT only) with AQA GCSE practice questions.
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Impact of environmental change (biology only) (HT only) explained
Distribution describes where organisms of a species are found within an ecosystem.
Read the full explanation
Environmental changes can make conditions more or less suitable, so species may spread into new areas, become restricted to smaller areas, or disappear locally. To evaluate an impact you use the information provided, such as survey data, maps or graphs, and reason about how a change affects the needs of the species. For example, if a river becomes warmer, a cold-water fish may move upstream while a warm-water species extends its range. Evaluation means weighing the evidence, identifying which species benefit or suffer, and explaining the likely effect on distribution using biological ideas such as temperature tolerance, water availability and gas exchange.
Environmental changes affect the distribution of species in an ecosystem. These changes include: • temperature • availability of water • composition of atmospheric gases.
Species are adapted to particular conditions, so when the environment changes, the places where they can survive also change. Temperature affects enzyme activity and the survival of organisms; a rise or fall outside a species' tolerance can force it to move or die out locally. Availability of water affects photosynthesis, transport and survival, so drought or flooding changes which species thrive. The composition of atmospheric gases, such as changing carbon dioxide or oxygen levels, affects photosynthesis and respiration and therefore growth and distribution. For example, increased carbon dioxide can favour fast-growing plants, while low oxygen in water can reduce fish populations. These changes shift the distribution of species within the ecosystem.
The changes may be seasonal, geographic or caused by human interaction.
Environmental conditions are not fixed, so the distribution and abundance of organisms shift over time. Seasonal changes follow regular cycles: day length and temperature alter in temperate regions, so many birds migrate and deciduous trees lose leaves, changing food and shelter. Geographic changes are longer-term shifts in where conditions suit a species, such as altered rainfall or a warming climate moving suitable habitat uphill or towards the poles. Human interaction covers direct and indirect effects: clearing hedgerows removes shelter, draining a wetland destroys breeding sites, while planting a wildflower strip can increase pollinator numbers. These categories overlap, and a change in one factor often alters competition and predator-prey relationships.
Your focus
- Interpret given information about an environmental change and species distribution.
- Explain how the change affects the suitability of the ecosystem for different species.
- Reach a justified judgement about the impact on distribution using the evidence provided.
Show all 9 objectives
- Name the environmental changes that affect species distribution.
- Explain the biological effects of temperature, water and atmospheric gas changes.
- Describe how these changes shift the distribution of species in an ecosystem.
- Classify a described environmental change as seasonal, geographic or caused by human interaction, giving a reason.
- Explain how a named environmental change affects the distribution or abundance of a named organism.
- Suggest how two causes of environmental change could interact to affect one population.
Impact of environmental change (biology only) (HT only) exam tips
Marking Points
- Define distribution as where a species is found within an ecosystem.
- Identify the environmental change described in the information and state whether it makes conditions more or less suitable.
- Link the change to the species' needs, such as temperature tolerance, water supply or oxygen availability.
- Use the given data, such as survey counts or maps, to support a judgement about how distribution changes.
- Explain that some species may increase their range while others decline or disappear locally.
- Reach a justified conclusion about the overall impact on the ecosystem.
- State that environmental changes alter the distribution of species in an ecosystem.
- Explain how temperature change affects enzyme activity and the survival of organisms.
- Explain how water availability affects processes such as photosynthesis, transport and survival.
- Explain how the composition of atmospheric gases, such as carbon dioxide or oxygen, affects photosynthesis and respiration.
- Link each change to a shift in where species are found, such as moving to more suitable areas or dying out locally.
- Seasonal changes are regular, predictable cycles such as changing day length, temperature or rainfall across the year.
- Seasonal change alters the availability of food, water or shelter, so organisms may migrate, hibernate or become dormant.
- Geographic changes are shifts in the distribution of suitable conditions, for example a species' range moving towards the poles or to higher altitude as the climate warms.
- Human interaction includes direct effects such as deforestation, drainage, pollution and building, and indirect effects such as introducing species or changing land use.
- A change in an environmental factor can alter the abundance and distribution of a species by affecting competition, predation or breeding success.
- Different causes can act together, so a seasonal drought may be made worse by abstraction of water for human use.
Examiner Tips
- 💡Always refer to the data or information given in the question rather than relying on memory alone.
- 💡Use comparative language such as increased, decreased, restricted or extended when describing distribution changes.
- 💡Structure your evaluation as change, effect on species, evidence, and overall judgement.
- 💡Learn the three named changes and be ready to give a biological effect for each.
- 💡Use examples such as drought reducing plant distribution or warmer water shifting fish species.
- 💡Link every effect back to distribution, not just to the survival of one organism.
- 💡Read the question carefully to identify whether the change described is seasonal, geographic or caused by human interaction, then justify your choice using evidence from the information given.
- 💡When asked to explain an effect, link the change to a named factor such as food, shelter or breeding sites, then state the consequence for the population.
- 💡Use comparative language such as 'increases', 'decreases' or 'shifts' rather than vague words like 'affects', and refer to distribution or abundance explicitly.
Common Mistakes
- Describing the environmental change without linking it to species distribution; correct this by explaining how the change affects where the species can survive.
- Ignoring the provided data and giving a general answer; correct this by quoting specific figures or patterns from the information.
- Assuming all species respond in the same way; correct this by recognising that different species have different tolerances and may benefit or suffer.
- Listing the three changes without explaining their effects; correct this by linking each change to a biological process and a distribution shift.
- Confusing the effect of carbon dioxide and oxygen; correct this by stating that carbon dioxide is used in photosynthesis while oxygen is used in respiration.
- Assuming a change affects all species equally; correct this by explaining that species have different tolerances and adaptations.
- Treating seasonal change as random weather: seasonal change is a regular, repeating pattern linked to the time of year, whereas weather events are short-term and unpredictable.
- Assuming geographic change always means the whole planet changes at once: it refers to a shift in the area where conditions suit a species, which may be local or regional.
- Describing human interaction only as habitat destruction: human activity can also create or improve habitats, for example by planting trees or creating ponds.