Inheritance and ecology · GCSE Biology
Biodiversity
Define biodiversity for GCSE Biology as the variety of species, explain why it stabilises ecosystems, and link deforestation, peat destruction, pollution and global warming to specific mechanisms of loss.
Biodiversity is the variety of living species (and, more broadly, genes and habitats). High biodiversity makes food webs stable. Name a human activity, the mechanism, and which species decline — “pollution is bad” scores nothing.
The important bits
What you need to know
- 1
Biodiversity is the variety of species in an ecosystem (exam core). High biodiversity means many species; low means few, often with one or two dominant.
- 2
High biodiversity increases stability: if one food source fails, consumers have alternatives. Low biodiversity (monoculture wheat) is vulnerable to one pest or disease.
- 3
Humans reduce biodiversity by habitat destruction (deforestation, building, quarrying), pollution (sewage, fertiliser, toxic chemicals, acid rain), over-exploitation (overfishing), and climate change from greenhouse gases.
- 4
Peat bog destruction: peat is a carbon store and a unique habitat. Cutting peat for compost or fuel releases CO₂ and removes specialist species.
- 5
Global warming shifts climate zones, melts ice, raises sea level, acidifies oceans (Higher), and can drive species beyond their range — extinction if they cannot move or adapt (adaptation here means existing alleles, not wishing).
- 6
Maintaining biodiversity matters for ecosystem services: pollination, clean water, medicines, food genetic resources, and stability that humans depend on.
- 7
Conservation methods: breeding programmes, habitat corridors, protected areas, international agreements, recycling to reduce landfill and extraction, using peat-free compost.
- 8
A food web with many links can survive the loss of one species better than a simple chain. That is the stability argument in exam language.
Quotations worth analysing
Short evidence. Real method.
“Biodiversity is the variety of species in an area.”
Then say why it matters: stability and resources. A list of cute animals is not a definition.
“Deforestation reduces biodiversity by destroying habitat.”
Name habitat loss, then fewer niches, then species decline. Add carbon-cycle impact if marks remain.
“Peat bogs are important carbon stores and habitats.”
Destruction releases CO₂ and removes specialist plants and animals. Suggest peat-free compost as a mitigation.
Go deeper
How do I turn “humans affect the environment” into six specific marks?
Pick one activity and follow it. Example: fertiliser on a field → rain leaches nitrate into a river → algae bloom → algae die → decomposers respire and use up oxygen → fish die (eutrophication). That is pollution with a chain, not a word. Example: palm-oil plantation → rainforest cut → orangutan habitat gone → species number falls; also less photosynthesis. Example: sulfur dioxide from burning coal → acid rain → soil and lake pH falls → enzymes in organisms denature or eggs fail. Each story names a chemical or a habitat and an organism. “Pollution kills animals” is a grade-3 sentence. Examiners pay for the mechanism. Biodiversity loss is the consequence at the end of the chain.
Go deeper
Why is a monoculture a biodiversity problem as well as a farming choice?
A wheat field has high productivity of one species and very few others. A pest or a fungus that likes wheat can spread easily (low genetic and species diversity). Hedgerows, beetle banks and crop rotation raise the number of species and can provide predators of pests. That is why conservation and yield are not always enemies, though there is a land-use trade-off. In the exam, contrast rainforest (high biodiversity, complex web) with plantation (low biodiversity, simple chain). Stability is the key word: more species, more alternative food, less chance the whole web collapses. Do not claim biodiversity means “lots of trees” if the question is a coral reef — species, not just plants.
Go deeper
How should I evaluate a conservation scheme?
State the aim: increase or protect species number / a named habitat. Method: reserve, corridor, captive breeding then release, legal protection, peat-free compost, fishing quotas. Benefit: gene pool kept, food web restored, carbon stored, future medicines. Limitation: cost, conflict with local farming, released animals may not survive, corridors can spread disease, climate change may still shift the habitat. Conclusion: works if habitat remains and local people have a stake. Seed banks and zoos are backups, not substitutes for habitat. Use a named example if you have one (red kite reintroduction, peatland restoration) but the mechanism matters more than the celebrity species.
See the idea in action
A peat bog is drained for garden compost. Specialist mosses and insects lose their waterlogged habitat, so species richness falls (biodiversity down). Stored carbon is exposed to oxygen, decay and combustion release CO₂, adding to the greenhouse effect, which can stress still more habitats. Using peat-free compost would reduce that demand. A student who writes only “the environment suffers” has named neither peat, carbon nor species. Eutrophication from fertiliser would be a different mechanism: nitrate → algal bloom → oxygen drop → fish death, which also cuts freshwater biodiversity.
Exam technique
Turn knowledge into marks
Define biodiversity as variety of species. For human impact, name the activity, the mechanism, and a consequence for species or carbon. Offer one conservation method that matches. Avoid the word pollution without a named pollutant.
Common mistakes
Do not give these marks away
- 01
Writing “pollution is bad” or “deforestation is bad” with no mechanism.
- 02
Defining biodiversity as “lots of animals” and ignoring plants, fungi and habitat variety.
- 03
Claiming conservation always reduces food production, or that one nature reserve fixes climate change.
What is biodiversity?
AThe amount of carbon dioxide in the air
BThe variety of species in an ecosystem
CThe number of food chains that have been drawn
DThe mass of all the foxes in a wood
Show the answer
The variety of species in an ecosystem. Biodiversity is species variety (and is greater when many species are present). CO₂ is a greenhouse gas, not the definition. One species’ biomass is not biodiversity.
Quick questions
If this is the bit you searched
What is biodiversity GCSE Biology?
The variety of species in a habitat or ecosystem. High biodiversity makes food webs more stable and provides resources humans depend on.
How does deforestation reduce biodiversity?
It destroys habitat and niches, so species that cannot live in the new plantation or field decline or become extinct locally. It also reduces a carbon store.
Why are peat bogs important?
They store carbon and support specialist species. Draining or burning peat releases CO₂ and removes that habitat.
What is eutrophication?
Fertiliser nitrates leach into water, algae bloom and then die, decomposers use up oxygen, and aquatic animals die — reducing biodiversity.