3.5 biology

• Food yield


  The food produced in an area per year. This is required to increase to feed the growing human population.
• Fertilisers


  Chemical which adds nitrates to the soil to improve plant growth or crop yield.
• Leaching


  The leaking of materials from soils into waterways.
• Algal bloom


  A seasonal abundance of algae.
• Pesticides


  General name for chemicals used to kill organisms that damage or feed on crop plants.
• Bioaccumulation


  The build-up of a toxic substance. As pesticides are passed along a food chain, toxicity increases and can reach lethal levels.
• Toxicity


  Poison level.
• Pollution


  Environmental damage caused by humans usually by release of substances to the environment.
• Biological control


  Natural control of pests using natural predators or parasites.
• DDT


  A toxic insecticide originally used to kill some species of mosquito.
• GM crop


  Term given to a plant that has had its genetic code altered, usually by adding a gene from another organism. These can be used to reduce the use of fertilisers and pesticides.
• Amino acids


  The building blocks of proteins that are made from nitrates.
• Proteins


  Substance that is made from amino acids.
• Nitrates


  The chemical that plants absorb from the soil to produce proteins.
• Nitrates are used to produce amino acids


  Amino acids are then made into proteins
• Fertilisers leaching from fields into water

  1. Fertilisers leach from fields into freshwater due to heavy rain

  2. This increases the growth of algae in the water (creates algal blooms)

  3. The blooms blocks out sunlight and kills plants

  4. Algae start to die and are broken down by bacteria along with the dead plants. They become food for the bacteria

  5. The bacteria divide and use up large quantities of the oxygen availability in the water

  6. This results in the death of many organisms so a decrease in biodiversity
• Genetically Modified (GM) crops

  Can be used to reduce the use of fertilisers
• Pesticides


  Are used to kill a range of pests that will affect the growth of a crop