Habitat destruction — Cambridge IGCSE Biology
Biodiversity, why habitats are destroyed, how humans damage food webs, and the effects of deforestation.
Revision notes
2 short notes, in the order of the specification. Each one in short:
Biodiversity is the number of different species that live in an area. Habitat destruction reduces biodiversity and is caused by clearing land for housing, crop plants and livestock, by extracting natural resources such as through mining, and by freshwater and marine pollution. Humans also harm habitats by altering food webs, because removing one species affects others.
Deforestation is the removal of forests on a large scale, for timber, farmland, housing, roads and mining. It reduces biodiversity and can cause extinction, because species lose their habitat and food. Without tree roots, soil is washed away and flooding increases. Carbon dioxide in the atmosphere rises because fewer trees photosynthesise and felled trees are burned or decay.
Exam questions
6 exam-style questions (15 marks), each with its mark scheme.
Answer the questionsFlashcards
5 cards: flip them, mark what you knew, and practise the rest.
Practise the cardsMind map
The whole of human influences on ecosystems on one page, so you can see where this subtopic fits.
Open the mind mapPrint it
Free PDFs to print or save.
Quick check questions
Define biodiversity.
Show answer
The number of different species that live in an area.
Give three reasons for habitat destruction.
Show answer
Housing, crop and livestock production; extraction of natural resources; freshwater and marine pollution.
How does deforestation lead to flooding?
Show answer
Fewer roots and leaves to absorb water, so more water runs into rivers.
How does deforestation increase carbon dioxide in the air?
Show answer
Fewer trees photosynthesise, and burning or decay of trees releases CO₂.
Frequently asked questions
How does deforestation affect the carbon cycle?
Deforestation increases carbon dioxide in the atmosphere. Fewer trees are left to take in carbon dioxide for photosynthesis, so less is removed from the air. When the felled trees are burned or decay, the carbon in them is released as carbon dioxide, by combustion or by the respiration of decomposers.
Why is biodiversity important to ecosystems?
Biodiversity, the number of different species in an area, matters because species are linked in food webs, so removing one species affects others. For example, if a predator is hunted out, its prey may increase and eat too much of the producers. Habitat destruction reduces biodiversity and can lead to extinction.
How does deforestation cause flooding?
Deforestation causes flooding because tree roots absorb water and leaves intercept rain. Without the trees, more rain water runs straight into rivers, so they flood more easily. Without tree roots to hold the soil together, rain also washes the soil away, which is called soil erosion.
What are the main causes of habitat destruction?
The main causes of habitat destruction are clearing land to increase the area for housing, crop plant production and livestock production; extracting natural resources by mining, quarrying and drilling; and freshwater and marine pollution, such as sewage, fertiliser and plastics, which makes water unsuitable for the organisms that live in it.
Written and checked against the Cambridge IGCSE Biology (0610) specification · Updated October 2026