food production 3.5 Flashcards
fertilisers
added to the soil to ensure plants have the nutrients they need to grow
what chemicals do fertilisers supply plants
nitrates
nitrates
they dissolve in soil water and are absorbed into plants
what are nitrates used for
used to produce amino acids which synthesised into plant proteins
what is leaching
when rainwater washed excess fertilisers from the soil into nearby fresh water
what can leaching increase
the algae populations which can cause algal blooms
algal bloom properties
very smelly, causes serious pollution problems and decreases aquatic biodiversity
stages of an algal bloom
1) fertilisers leach into fresh water, adding extra, unwanted nitrates
2) algae feed off of the additional nitrates resulting in them growing and multiplying rapidly causing algal bloom
3) algal blooms reduces light levels, which kills aquatic plants
4) the dead plants and some dead algae become food for bacteria which increase greatly in number
5) the bacteria use up large quantities of oxygen, reducing the oxygen available for other organisms
6) this leads to further reduction of biodiversity as more freshwater organisms die due to lack of oxygen
alternative to fertilisers
genetically modified crops
what are pesticides
chemical substances which are sprayed into crops to kill organisms which reduce plants growth
what can pesticides reduce
inter specific and intraspecific competition between crops
disadvantages of pesticides
pesticides are non biodegradable and therefore can accumulate in the bodies of organisms over time, this is known as bioaccumulation
alternatives to pesticides
deliberate introduction of a predictor or a parasite of pest, biological control
advantages of biological control
- no chemicals being added
- specific to the particular pest being dealt with
- much cheaper after initial set up
disadvantages of biological control
- sometimes the introduced species can itself become a pest
- it doesn’t guarantee the pest is killed
- predator can leave the environment
