Life on Earth - PROBLEMS with Fertilisers and Pesticides Flashcards
1
Q
What does the term ‘leaching’ refer to?
Why is it bad?
A
- Refers to the process of fertilisers being washed by the rain from soil into rivers or lakes.
- Bad because it adds unwanted nitrates to the water.
2
Q
How can additional nitrates affect plants?
A
They will increase the rate of plant growth
3
Q
Explain the timeline of leaching and its long term affects
A
- Leaching occurs, stimulating algae growth and increases algal populations, causing an algal bloom
- Algal bloom present? → Light levels are reduced → Aquatic plants lower down in the river/pond/lake are killed
- Dead plants and algae become food for bacteria, so bacteria populations increase
- The bacteria use up a lot of oxygen during respiration, reducing oxygen avaliablity for other organisms
4
Q
Why are algal blooms bad?
A
They reduce the biodiversity of aquatic habitats
5
Q
Name one method of reducing fertiliser use
A
GM crops
6
Q
Name two ways in which pesticides are harmful
A
- Toxic to unintended species
- Can cause bioaccumulation
7
Q
Define the term ‘bioaccumulation’
A
the accumulation of toxic substances in the bodies of organisms over time
8
Q
Explain the process of ‘Biomagnification’
A
- bioaccumulation taken place in prey species = feeding interactions pass them along food chains.
- Each predator consumes many prey = toxicity level increases at each level of the food chain.
- At higher levels of the food chain, the toxicity can become lethal
9
Q
Name two ways that pesticide use can be reduced
A
GM crops, biological control
10
Q
Define biological control
A
pest population is reduced by introducing its natural enemy or predator on purpose
