Transcript Environmental Biology & Genetics

Environmental Biology &
Genetics
Energy Flow
Ecosystems
An ecosystem is a natural unit composed
of living organisms and their non-living
environment, e.g. a woodland.
A habitat is the place where an
organism lives, e.g. greenfly live on the
leaves of the trees.
An organism’s niche is the role it plays
within the ecosystem e.g a tawny owl is
top predator in a woodland.
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Ecosystems
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Ecosystems
A population is the total number of
organisms of one species living in a
habitat, e.g. the total number of
greenfly in the woodland.
A community is made up of all the living
organisms in a habitat, e.g. all the trees,
grass, insects, birds, etc..
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Ecosystems
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Ecosystems
A species is a group of organisms which
can interbreed to produce fertile
offspring.
Donkey
Horses and donkeys can
mate to produce a mule –
but mules are not fertile
so horses and donkeys
are separate species
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Horse
Mule
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Ecosystems
All of the energy required by all living
organisms in an ecosystem comes from
the sun.
Light energy from the sun is converted
to chemical energy by plants in a
process called photosynthesis.
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Producers & Consumers
Producers are organisms which can
produce their own food by
photosynthesis – usually green plants.
Consumers are animals which consume
(eat) other organisms. They cannot
make their own food.
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Producers & Consumers
A primary consumer is an animal which
eats plants, and is also known as a
herbivore.
A secondary consumer is an animal
which eats primary consumers, and is
also known as a carnivore.
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Producers & Consumers
An omnivore can eat both plants and
animals.
Decomposers are bacteria and fungi
which break down dead plants and
animals for energy and release their
nutrients back into the ecosystem.
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Producers & Consumers
An animal which hunts other animals for
food is called a predator.
An animal which is hunted by other
animals as food is called prey.
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Food Chains & Webs
A FOOD CHAIN shows a feeding
relationship. It is usually written as:
Green plant
herbivore
carnivore
The arrows in a food chain point from
food to feeder and show the direction
of energy flow.
A food chain always starts with a
producer (green plant).
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Food Chains & Webs
Energy is transferred in the form of
chemical energy in food from plants to
animals and then to other animals.
A green plant (producer) can be eaten
by a herbivore.
The herbivore in turn can be eaten by a
carnivore.
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Food Chains and Food Webs
ENERGY
ENERGY
Green Plant
Rabbit
Fox
PRODUCER
PRIMARY
CONSUMER
(HERBIVORE)
SECONDARY
CONSUMER
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(CARNIVORE)
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Food Chains & Webs
Feeding relationships are more
complicated than food chains suggest.
Food chains interconnect at many
points.
This interconnection of food chains is
called a food web.
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Food Chains & Webs
WEASEL
FOX
HEDGEHOG
FROG
SNAIL
RABBIT
VOLE
PRIMROSE
PLANT
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OWL
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OAK
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Energy Flow and Loss
Every time one organism eats another,
energy is transferred from the food to
the feeder.
The arrow indicates the direction of
energy flow.
E.g.
Oak leaf
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Caterpillar
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Shrew
Badger
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Energy Flow and Loss
Not all the energy available at each step
in a food chain is passed onto the next
step.
Only about 10% is passed on.
90% of the energy is lost e.g. as:
Movement
Heat production
Waste.
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Pyramid of Numbers
A pyramid of numbers is a diagram
which represents the number of
organisms at each stage in a food chain.
A pyramid of numbers can look like:
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Pyramid of Numbers
Number of
organisms
decrease
Thrush
Size of
organisms
increase
Ladybird
Greenfly
Grass
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Pyramid of Numbers
Thrush
Ladybird
Greenfly
Grass
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Pyramids of Energy
A pyramid of energy is a diagram which
represents the amount of energy
available at each level of a food chain.
It is usually measured in kilojoules of
dry mass per square metre per year.
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Pyramid of Energy
100 kJ
1 000 kJ
10 000 kJ
100 000 kJ
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Pyramid of Biomass
A pyramid of Biomass is a diagram which
represents the total mass of organisms
at each level of a food chain.
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Pyramid of Biomass
Sparrows
Caterpillars
Oak leaves
The energy available to the caterpillars is less
than the energy available to the sparrows, and
therefore, the caterpillars produce a greater
biomass than the sparrows.
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Vocabulary
ecosystem
habitat
niche
population
community
producer
primary consumer
secondary consumer
herbivore
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carnivore
predator
prey
decomposer
species
pyramid of numbers
pyramid of biomass
pyramid of energy
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