The Ecosystem: Environmental Impact Assessment Report
Topic 2: The Ecosystem
2.1.1
Biotic: living factors or components, e.g. plants and animals.
Abiotic: non-living factors or components, e.g. soil, water, wind, etc…
2.1.2
Trophic level: is the position that an organism or a group of organisms in a community occupies in a food chain.
2.1.3
A food chain shows the flow of energy from one organism to the next.
A food web is a complex network of interrelated food chains.
Producers (autotrophs): manufacture their own food from simple inorganic substances (including sun light).
Consumers (heterotrophs): feed on autotrophs or other organisms to obtain energy.
Example of different feeding levels:
Trophic level 1 – producer e.g. grass
Trophic level 2 – herbivore (primary consumer) e.g. grasshopper
Trophic level 3 – carnivore (secondary consumer) e.g. field mouse
Trophic level 4 – carnivore (tertiary consumer) e.g. eagle
Top carnivores are found at the top of the trophic level (nothing feeds on them) e.g. lions, tigers, etc…
See information above and fig. 3.26-3.30 on Pgs 48 and 49 (Textbook)
2.1.5
Bioaccumulation: If a chemical in the environment breaks down slowly or does not break down at all, plants may take it up and animals may take it in when they breathe. If they do not excrete or egest it, it will accumulate in their bodies over time. Its concentration will therefore build up until eventually it may be high enough to kill the organism.
Biomagnification: If a herbivore eats a plant which has chemicals in its tissues, the herbivore will take in the chemical. However, because the herbivore will eat many plants the concentration of the chemical in the herbivore will be higher than the plant. If a carnivore then eats those herbivores exposed, because it will eat many of them, the concentration of the chemical will increase in the carnivore. In this way the chemical concentration will increase as it moves up the trophic level. The top trophic
2.1.1
Biotic: living factors or components, e.g. plants and animals.
Abiotic: non-living factors or components, e.g. soil, water, wind, etc…
2.1.2
Trophic level: is the position that an organism or a group of organisms in a community occupies in a food chain.
2.1.3
A food chain shows the flow of energy from one organism to the next.
A food web is a complex network of interrelated food chains.
Producers (autotrophs): manufacture their own food from simple inorganic substances (including sun light).
Consumers (heterotrophs): feed on autotrophs or other organisms to obtain energy.
Example of different feeding levels:
Trophic level 1 – producer e.g. grass
Trophic level 2 – herbivore (primary consumer) e.g. grasshopper
Trophic level 3 – carnivore (secondary consumer) e.g. field mouse
Trophic level 4 – carnivore (tertiary consumer) e.g. eagle
Top carnivores are found at the top of the trophic level (nothing feeds on them) e.g. lions, tigers, etc…
See information above and fig. 3.26-3.30 on Pgs 48 and 49 (Textbook)
2.1.5
Bioaccumulation: If a chemical in the environment breaks down slowly or does not break down at all, plants may take it up and animals may take it in when they breathe. If they do not excrete or egest it, it will accumulate in their bodies over time. Its concentration will therefore build up until eventually it may be high enough to kill the organism.
Biomagnification: If a herbivore eats a plant which has chemicals in its tissues, the herbivore will take in the chemical. However, because the herbivore will eat many plants the concentration of the chemical in the herbivore will be higher than the plant. If a carnivore then eats those herbivores exposed, because it will eat many of them, the concentration of the chemical will increase in the carnivore. In this way the chemical concentration will increase as it moves up the trophic level. The top trophic