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biology 0610printed 266 · PDF 266
328 pagesrevision 46933
printed 266 · PDF 266
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Notes
Energy flow
●The Sun is the main source of energy input to all biological systems.
●The energy from the Sun is captured as light energy in plants, which are then eaten
by animals who store energy in the form of chemical energy. These animals are eaten
by other animals and then eventually these other animals also die and are
decomposed by bacteria after which their energy is released to the environment.
●The transfer of energy in this way from one organism to another, is known as a food
chain and it always begins with a producer(an organism that can produce food).
●Multiple food chains together are called a food web.
Food Chains
●A producer is an organism that makes its own organic nutrients(usually using energy
from sunlight) through photosynthesis.
●A consumer is an organism that gets its energy by feeding on other organisms.
● Consumers can be called primary, secondary, tertiary or quaternary based on their
position in the food chain.
●Primary consumers are the ones that eat plants such as the deer above; secondary
consumers then eat primary consumers; tertiary consumers then eat secondary
consumers; quaternary consumers then eat tertiary consumers.
●A herbivore is an animal that gets its energy by eating plants.
●A carnivore is an animal that gets its energy by eating other animals.
●A decomposer is an organism that gets its energy from dead or waste organic
material.
●All herbivores are primary consumers and most decomposers are bacteria.
●We can use food chains/webs to see the impacts of overharvesting, which reduces
the number of producers in the food chain or of adding a new species to a habitat,
which reduces the food for other species already in the habitat.
Pyramid of numbers and biomass