Ecosystems
Learning Intention
• To be able to describe what is meant
by a habitat, population, community
and ecosystem.
Habitat
• An organisms habitat is the place
where it lives.
Population
• A population is all the members of
one species in an ecosystem.
Population of
sea turtles
Population
of dolphins
Water
habitat
Community = all the plants and animals in a habitat
Example of an
ecosystem:
Ecosystem = Community + Habitat
Learning Intention
• To be able to:
– Give an example of a food chain.
– Identify the producers, primary and
secondary consumers in a food chain.
What is a food chain?
Photosynthesis.........
What happens to the
food plants make in
photosynthesis?
Food Chains
• Food chains show which organisms eat
other organisms
Grass
Rabbit
Fox
• The arrows show the transfer of energy
from one organism to the next.
• It also helps to think of the arrows as
meaning ‘is eaten by’.
• Producers - organisms which can make
their own energy from carbon dioxide and
water using sunlight for energy (plants)
Primary consumer organisms which eat
producers.
Secondary consumers - organisms which eat
primary consumers.
Secondary consumers are predators
Arrange these into food chains
1.
2.
3.
4.
Lion, grass, Zebra
Weasel, fieldmouse, owl, wheat
Greenfly, oak leaf, thrush, ladybird
Herring, animal plankton, human,
plant plankton
5. Frog, hawk, grass, snake,
grasshopper
Learning Intention
• To be able to describe the path of
energy flow in a food chain.
Energy loss
• Some energy is lost at each stage in a food chain.
• Each organism in a food chain uses some of the
energy to build up its body and grow.
• Most of the energy that organisms gain in a food
chain is used up when the organism moves about,
and in warm-blooded animals, to keep warm.
• This means that, as humans, it is more efficient
for us, and we receive more energy from, eating
plants.
Questions
1.
What is the source of energy entering a food
chain?
2.
What does every food chain begin with?
3.
Name two ways in which energy can be lost in a
food chain.
3 things
• Write down 3 things you know now
that you didn’t know at the start of
the lesson.
• Once you have both finished, share
them with the person beside you.
Learning Intention
• To be able to give an example of a
food web.
What is a food web?
• A food web is made up of 2 or more
food chains joined together.
• For example – Grass
– Grass
– Grass
Rabbit
Fox
Caterpillar
Bird
Beetle
Mouse
Fox
Would make this food
web
More complex food webs
Food Webs
Small bird
Ladybird
Spider
Owl
Vole
Earthworm
Greenfly
Herb
The Food Web
shown is from a
typical woodland
community.
Soil fungi
Moth caterpillar
Live oak leaf
Dead oak leaf
Carnivores
Herbivores
Decomposers
Producers
Constructing a food web
Consumer
Rabbit
Food
Oak, Primrose
Vole
Snail
Frog
Weasel
Owl
Hedgehog
Fox
Primrose
primrose
snail
Vole, rabbit
Vole
Snail, vole
Frog, hedgehog, rabbit,
weasel
Learning Intention
• Explain relationships between
different organisms in a food web
and effects of removing a species.
Questions
1. What will happen to the number of clown fish if the sharks
become vegetarian?
2. What effect will this have on the number of zooplankton?
3. What will happen to the Blue Regal fish if a disease wipes out
the small invertebrates.
Food Web
Great White Shark
Blue Regal
Clown Fish
Zooplankton
Small
Invertebrates
Algae
Sea Turtle
Learning Intention
• To be able to arrange organisms from
a food chain into pyramids of number
and biomass.
FOOD CHAIN
GRASS
1000 GRASS
PLANTS!
CRICKET
FROG
100 CRICKETS! 10 FROGS!
HAWK
1!
Discussion
• What do you notice about the size of the actual
organisms as you move along a food chain?
• What do you notice about the number of
organisms at each stage as you move along a food
chain?
• Why do you think the number of organisms at
each stage is changing?
(Do big organisms eat the same amount as small
organisms?)
Pyramids of Number
• The relationship takes the form of a
pyramid because
– The energy loss at each link in the food chain
limits the quantity of living matter that can be
supported at the next level.
PYRAMID OF NUMBERS
• Shows population size at each stage
in a food chain
1
HAWK
10
FROGS
100
CRICKETS
1000
GRASS PLANTS
PROBLEM!!!!!
Can you explain the shape of this pyramid
of numbers???
Choose one of the pyramids of numbers above to represent
each of the three food chains below.
DANDELIONS
PEAR TREE
RABBITS
APHIDS
GREEN PLANTS
FOX
LADYBIRDS
SLUGS
FROG
FLEAS
PARTRIDGE
FOX
Pyramids of biomass
• The biomass of a population is the total mass of
living things.
• In a food chain the biomass of the producer is
greater than the biomass of the primary
consumer, which in turn is greater than that of
the secondary consumer.
• Since biomass decreases at each level, it can also
be represented as a pyramid shape.
Pyramid of Biomass
The pyramid of biomass shows the biomass of a population in an
ecosystem.
E.g. Oak tree
Insects
Birds
Birds
Insects
Oak tree
A pyramid of biomass is
always a true pyramid
shape.