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Habitat destruction Edexcel International GCSE Biology revision

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In plain words

Half the world's forests are gone, cleared for farms, timber and towns. When the trees go, so do the animals that lived in them, and so does the soil they held in place. And the carbon the trees stored ends up in the air.

Three things to know

  1. Habitats are destroyed to make room for housing, crops and livestock, to extract resources such as timber and minerals, and by pollution of fresh water and the sea.
  2. Deforestation reduces biodiversity and can cause extinction. With no roots to hold it, soil is washed away, and without trees to take up water there is more flooding.
  3. Deforestation adds carbon dioxide to the air: there are fewer trees to take it in by photosynthesis, and burning or rotting the wood releases it. It also disturbs the water cycle, because less water returns to the air from leaves.

Tips and tricks

  • Four effects of deforestation to learn: loss of biodiversity and extinction, soil erosion, flooding, more carbon dioxide.
  • Two reasons for the extra carbon dioxide: less photosynthesis, and burning or decay of the trees.
5 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

Habitat destruction: 5 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

  1. What is biodiversity?
    • the number of trees
    • the number of different species in an area (the answer)
    • the amount of soil
    • the size of a forest

    Rainforests have very high biodiversity.

  2. Which is an effect of deforestation?
    • less carbon dioxide in the air
    • soil erosion (the answer)
    • more biodiversity
    • less flooding

    There are no roots to hold the soil.

  3. Why does deforestation increase carbon dioxide in the atmosphere?
    • Trees give out carbon dioxide by photosynthesis.
    • Fewer trees take it in, and burning the wood releases it. (the answer)
    • Soil absorbs less oxygen.
    • Animals breathe more.

    Both effects push the level up.

  4. Why does deforestation cause flooding?
    • More rain falls.
    • There are no trees to take up water, and it runs off the land. (the answer)
    • Rivers get deeper.
    • The soil gets thicker.

    Bare soil is also washed into rivers.

  5. Which is a reason for clearing forests?
    • to increase biodiversity
    • to make land for crops and livestock (the answer)
    • to reduce flooding
    • to store carbon

    Farming is the biggest cause of deforestation.

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