5. food production

Question 1

why are fertilisers good for intensive farming?

Answer 1

nitrates are essential for plant growth - they dissolve in water and are absorbed into plants by plant roots. nirtates are used by plants to make amino acids which are synthesised (joined together) into protein in the plants.

Question 2

describe how fertilisers can cause problems on the environment (6 points)

Answer 2

• fertilisers can leach into fresh water, adding extra, unwanted nitrates
• this will increase the algal populations which can cause algal blooms (excessively large numbers of algae)
• algal blooms reduce light levels, killing aquatic plants below them in the water.
• these dead plants, as well as dead algae, become food for bacteria which will greatly increase in number.
• the bacteria use up large quantities of oxygen, reducing the oxygen availability for other organisms
• other organisms die

Question 3

describe an alternative to using pesticides

Answer 3

genetically modified (GM) crops can be used to reduce the number of fertilisers - this means that less fertiliser needs to be used to get the same crop yield

biological control (i.e. a predator or parasite is introduced into the crop to eat the insect pests)

Question 4

why are pesticides bad for the environment

Answer 4

pesticides sprayed onto crops can accumulate in the bodies of organisms over time. as they are passed along food chains, toxicity increases and can reach lethal levels.

Question 5

what is bioaccumliation

Answer 5

the build up of toxic substances in living organisms