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Glossary Biotic Factors
Ecosystem Decomposer ­ Microrganism (bacteria/fungi) which feed on
Environment dead or waste organic matter
Detritivore ­ Animals which feed off detritus eg. earthworm
Community Detritus ­ Organic matter that has been acted on by
Habitat Trophic level ­ The level at which an organism feeds at
Abiotic Factors
Producer- A plant that uses sunlight energy to make food by
the process of photosynthesis
Primary Consumer ­ A herbivore which feeds on a producer
Secondary Consumer- A carnivore which feeds on a primary
Tertiary Consumer - An animal which feeds on a secondary
Quaternary Consumer - An animal which feeds on a tertiary…read more

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Food Chains
Producer Primary Consumer Secondary Consumer
Vegetation Beetle Fox
3 tropic levels the food chain.
Direction of energy transfer
Why is the number of tropic levels set at an upper limit of 5?
Not enough energy to support another tropic level, as at each tropic level energy
is lost to the food chain. E.g. Heat loss by respiration.
Energy Transfer In Communities
Solar Chemical Chemical Chemical
energy energy energy energy
Energy transfers never 100% as with every energy level there is heat loss by
respiration to release energy which is used to drive metabolic reactions e.g. cell
division, muscle contraction…read more

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Energy Flow Through Ecosystem
·Only 10% of what eaten, becomes built
·Light Energy ·Loss to food into organism's body. Energy transfer,
Lost by reflection chain through producer to primary
·Some of food consumed remains consumer is 5%
from the leaf excretion, death undigested and lost as faeces (egesta)
surface and heat loss · Plant material is not
through ·Loss of energy in processes of feeding, readily digestible due
respiration digestion, moving and excretion. to cellulose (egesta)
wavelength to be Respiration provides ATP for these
absorbed by processes so some chemical energy ·Some plant material
chlorophyll taken in as food is given off as heat not consumed die to
trampled grass ad
Solar Primary Secondary inaccessible roots.
Energy Consumer Consumer
Energy transfer
between p.consumer
an s.consumer is 10%
·Animal tissue more
Decomposers digestible
The decomposers are fungi and ·Carnivores may be
bacteria which obtain energy extremly specialised
and raw materials from animal for prey consumption
and plant remains BUT
·Some animal tissue
not readily digestible
e.g. hooves, hide…read more

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Energy Transfer and Efficiency
· Mammals and birds Homeotherms (keep body temperature constant by using metabolism to generate
heat energy).
· Fish, amphibians and reptiles are Poikilotherms. Poikilotherms body temperatures fluctuate with
environmental temperatures and DO NOT use heat energy from metabolism to maintain body
temperatures. Hence more of the food poikilotherms eat is converted into new cells and tissues that can
be eaten by consumers and therefore more chemical potential energy is available to consumers (i.e.
more efficient)
· Small mammals have a large surface area : volume ratio and large mammals have a small surface area
: volume ratio. Therefore small animals lose more heat relative to their size than larger mammals and
therefore metabolic rate may be higher to generate more heat energy to maintain body temperature.
Hence more chemical potential energy in the food they eat is converted into heat energy (lost to food
chain) and less to new cells and tissues.
· Carnivores convert food they eat more efficiently into new tissues than herbivores (primary consumers).
Herbivores diet is higher in cellulose and lignin, (difficult to digest) then a carnivore which can be high
protein. Herbivores thus lose a higher proportion of energy through egestation.
Why are trout kept in fish farms?
Trout are poikilotherms and don't use chemical potential energy for metabolism to maintain a constant
temperature. Fish farms means the fish are restricted in movement and so less energy again lost to
food chain. Trout are carnivores and the is little waste from food pellets which are easier to digest,
less energy lost through digestion and egestion hence more food assimilated. They are harvested
when still young as most energy efficient as more of the food is going to new cells and tissue
during rapid growth.…read more

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Energy Flow Through Food Chains
First Energy Transfer
Sun Producer
Plant/producer traps and absorbs solar radiation from the sun in the process of photosynthesis. In this process, light
energy converted into chemical energy (glucose)
Not all of the light energy is absorbed by the plant, however some is an inappropriate wavelength to be absorbed by
chlorophyll (i.e. not photosynthetically active) and some light is reflected or fails to strike leaf.
Second Energy Transfer
Producer P. Consumer
Some of the plant material is eaten by primary consumers (herbivores)
Plant material that dies is not eaten by p.consumers, this enters the decomposer food chain not consumer food
chain. (detritus food chain)
What is humus? Organic matter in the soil
Some of the CHO produced by photosynthesis will be used by the plant itself in the process of respiration, where
energy will be lost from the food chain as heat energy (so this is not transferred to the p.consumer)
Third Energy Transfer
P. Consumer s. Consumer
What does a herbivore do with the plants it eats?
Digests plant material and assimilates the products of digestion, some plant material not digested and therefore is
egested (egesta/faeces). Some of the assimilated energy is lost as urine (excreta). Some lost as heat through
process of respiration. P. consumers move around and this requires energy, so this would also be a loss of energy to
the food chain. (energy not transferred to s.consumer)
Egesta and excreta will enter the decomposer food chain rather than consumer food chain.
Hence s.consumer only receives a fraction of the energy taken in by p.consumer ­ 10%…read more

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