CIE IGCSE Biology

Revision Notes

21.1 Food Supply

Improving Food Production

  • Modern technology has increased food supply substantially in the following ways:
    • Agricultural machinery has replaced humans and improved efficiency due to the ability to farm much larger areas of land
    • Chemical fertilisers improve yields – fertilisers increase the amount of nutrients in the soil for plants, meaning that they can grow larger and produce more fruit
    • Insecticides and herbicides – these chemicals kill off unwanted insects and weed species, meaning that there is less damage done to plants and fruit lost to insects (insecticides), as well as reducing competition from other plant species (herbicides)
    • Selective breeding – animals and crop plants which produce a large yield are selectively bred to produce breeds that reliably produce high yields

Modern agriculture, IGCSE & GCSE Biology revision notesModern agricultural processes allows for cultivation of much larger areas of land for crop plants

Monocultures

  • Monoculture farming means that on a given area of agricultural land only one type of crop is grown (eg trees for palm oil grown in Indonesian rainforest)
  • This large scale growth of a single variety of plant does not happen naturally in ecosystems, where there are usually many different species of plants growing which, in turn, support many species of animals (high biodiversity)
  • In monocultures, biodiversity is much lower
  • Another issue with monocultures is the increase in pest populations – if a particular pest feeds on a crop, farming it in large areas repeatedly means there is an ample supply of food for the pest, causing the population to increase
  • Often farmers will spray insecticides onto crops in order to control the pests. This leads to:
    • harmless insects being killed as well
    • pollution by pesticides (which are often persistent chemicals which accumulate in food chains)
    • in many instances where they are used repeatedly for specific pests, the pests may eventually become resistant to them, reducing their effectiveness

Palm oil production, IGCSE & GCSE Biology revision notes Palm oil production has increased rapidly over the last 30 years

Intensive Livestock Farming

  • In developed countries, large numbers of livestock are often kept in an area that would not normally be able to support more than a very small number
  • They are often fed high energy foods, regularly given medication such as antibiotics as a preventative measure against disease and kept in artificially warm temperatures and small spaces that do not allow for much movement
  • Ecological issues with intensive farming include:
    • reduction in biodiversity in areas where large amounts of land are used to graze cattle (as only grass is grown so in effect it becomes a monoculture)
    • overgrazing can lead to soil erosion
    • large numbers of cattle produce large amounts of methane, a greenhouse gas
Extended Only

Global Food Supply

  • When people do not receive enough food, famine occurs
  • This can be caused by a variety of factors, including natural disasters, such as drought and flooding, increasing population, poverty, and unequal food distribution
  • As the global human population increases, food production must also be increased to support the increasing population
  • This is a problem as more land is required to grow crops and animals, meaning that deforestation is happening at an increasing rate, and there is also an increasing amount of greenhouse gases emitted from animal production
  • Greenhouse gases cause global warming, which is a worldwide issue that leads to increased natural disasters, such as tropical storms and drought, as well as rising sea levels, which floods homes and decreases the amount of habitable land

Author: Jenna

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.
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