3.5 human impact on the environment
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What are fertilisers?
products that are used to add extra nitrate to the soil to help plants grow
Give an example of biological control
release parasitic wasps to reduce aphids
Explain the importance of nitrates to plant growth
• plants absorb nitrates through their roots • they use this as a source of nitrogen to produce proteins • nitrogen is also a major component of chlorophyll
What is biological control?
the use of natural predators to control pests
What are the advantages and disadvantages of biological control?
advantages - only needs to be applied once and is effective disadvantages - it’s a slow process and it cannot wipe out the entire pest population. It can only be done in enclosed areas as it does not work well in open areas
Give an example of an indicator species for fresh water pollution by organic waste
low freshwater invertebrates–> high freshwater pollution
Give an example of an indicator species for sulphur dioxide pollution
low lichen populations–>high sulphur dioxide concentration
What are monocultures?
large areas containing just one crop
What are advantages and disadvantages of monocultures?
advantages - higher yields and it only requires one method of farming disadvantages - it destroys soil nutrients and to counteract this large amounts of harmful chemicals have to be used. these can end up in the human food chain
Why does feeding a growing population require intensive farming?
It makes farming more efficient by producing a larger crop yield or more meat
What is intensive farming?
the use of: -herbicides -pesticides -fertilisers -battery farming animals to produce a higher crop yield or more meat
What are pesticides?
chemicals used to control the levels of unwanted plants(herbicides) or insects(pesticides)
What are the problems with fertilisers entering freshwater?
it causes algal blooms
What is an algal bloom?
• fertilisers run into water • fertilisers make the algae grow • this blocks out sunlight to the plants below • plants at the bottom of the water die and start to rot as bacteria eat them • bacteria grow and use the oxygen • insects and fish that need oxygen suffocate and die
What does aerobic mean?
in the presence of or involving oxygen
What is bio accumulation?
the build up of toxic substances in living organisms
what are nitrates?
nutrients absorbed from soil by plants to produce amino acids
What are the problems with pesticides?
• some insecticides aren’t specific and kill other insects as well • bioaccumulation happens and the toxicity level builds up in carnivores and can eventually reach levels that can be lethal or that can damage their reproduction
What are alternatives to fertilisers?
• genetically modified crops (GM crops) - plant nitrogen fixing plants such as peas and clover
What are alternatives to pesticides?
• genetically modified crops (GM crops) - biological control
What is integrated pest management?
• a combination of biological control and pesticides - it reduces the amount of pesticides that farmers need to use