Fertilisers and food production

• What do fertilisers provide?

  fertilisers provide chemicals to increase the nutrient levels, such as nitrates in the soil
• how does overuse of pesticides affect ecosystems,?


  overuse kills beneficial insects which can lead to an imbalance in the ecosystem
• why are some crops genetically modified?

  to make them resistant to herbicides or pests
• What to fertilisers help to incease?

  crop yield
• How do fertilisers leach into rivers, lochs and ponds?

  heavy rainfall washes fertilisers from fields into the water
• What is the wash off of fertiliser called?

  leaching
• How does fertiliser in the water effect the algae levels?

  fertilisers greatly increase the growth of algae in the water
• What is an algal bloom?

  Excessive growth of algae in water, this can block out light to lower levels of water
• When do algal blooms die?

  when there is less nutrients and there is less light for photosynthesis
• What happens when the algae decay?

  they are decomposed by aerobic bacteria. The increased number of bacteria causes oxygen concentration to decrease
• What does low oxygen concentration in water result in?

  the death of many other organisms & reduction in biodiversity
• What are genetically modified (GM) crops?

  Crops with altered DNA, this can allow them to use nutrients better
• Why would GM crops be used?

  Increased crop yield, resistance to pests/diseases, tolerance to herbicides, and improved nutritional content.
• What are pests?

  plants and animals that damage crops and reduce crop yield
• What is bad about pesticides?

  they are passed along the food chain and build up in the bodies of organisms at each level in the food chain
• How do pesticides enter the pests body?

  by eating the plant sprayed with pesticides, the pesticides remain in their body and are eaten and passed along
• What happens as levels of pesticides build up?

  they become more toxic at each level in the food chain, and can sometimes be lethal causing organisms at the top of the food chain to die
• What is bioaccumulation?

  the build up of toxic substances in living organisms
• What is a biological control?

  a natural control of pests using natural predators, parasites etc
• What are pesticides?

  the general name for chemicals used to kill organisms that damage or feed on crop plants
• What is toxicity?

  poison level
• What does the increasing population mean for the reliance of food?

  The increased human population requires an increased food supply
• How do plants absorb nitrates?

  nitrates are dissolved in the soil and then absorbed by plants
• What are aerobic bacteria?

  Bacteria that require oxygen to grow and survive.
• What can GM crops be used for?

  Can be used to reduce the use of fertilisers
• What can be an alternative to pesticides?


  Biological control (using organisms eg. parasites), GM crops