Ecosystem

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6
Ecosystem
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6 The ecosystem

• 6.1 What is an ecosystem?
• 6.2 What is environment?
• 6.3 Energy flow within an ecosystem
• 6.4 The accumulation of toxic substances along
  food chain (Extension)
• 6.5 Cycling of materials
• 6.6 Ecological interdependence of organisms
  (Extension)

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6.1 What is an ecosystem?
6.1
What is
Ecosystem ?
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6.1 What is an ecosystem?
A group of organisms of the same species
Population
A
Population
B
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6.1 What is an ecosystem?
The place where an organism occurs is called
Habitat
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6.1 What is an ecosystem?
All the populations live in the same habitat make
up
Community
Population A B same habitat
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6.1 What is an ecosystem?
Interactions among populations
Interactions between populations and environment
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2
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6.1 What is an ecosystem?
Interactions among populations
Interactions between populations and environment
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2
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6.1 What is an ecosystem?
The Study of Ecosystem
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6.1 What is an ecosystem?
The ants live inside the grasses which is
different to the outside.
This particular area is called microhabitat
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6.2 What is environment?
6.2
What is
Environment ?
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6.2 What is environment?
Environment
Abiotic factors
Biotic factors
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6.2 What is environment?
Abiotic factors
Soil
Rainfall
Temp.
Humidity
Light
Wind
pH
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Abiotic factors
6.2 What is environment?
Temp.
Activity
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Abiotic factors
6.2 What is environment?
Temp.
Summary
Affects
organism activity
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Abiotic factors
6.2 What is environment?
Change
Temp.
Less affected
More affected
since its body temperature varies with the
environment
since it can keep its body temperature steady
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Abiotic factors
6.2 What is environment?
Light
Food formation
Flowering
Leaf shape
1
2
3
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Abiotic factors
6.2 What is environment?
Light
Animals
Food formation
1
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Abiotic factors
6.2 What is environment?
Light
Nocturnal
Diurnal
Behaviour
Activities
1
2
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Abiotic factors
6.2 What is environment?
Light
Nocturnal
Diurnal
Behaviour
1
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Abiotic factors
6.2 What is environment?
Rainfall
Humidity
On land,
Organisms reduce water loss by
Animal
Plant
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Abiotic factors
6.2 What is environment?
Wind
Pollen
Pollination
Spores
For dispersal
Seeds
Fruits
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Abiotic factors
6.2 What is environment?
Soil
A habitat for plant and animals
Source of nutrients for plant and animals
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Abiotic factors
6.2 What is environment?
pH
while some are tolerant of acid or alkaline soils.
The pH of soil
Most plants prefer to a neutral pH,
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6.2 What is environment?
Environment
Abiotic factors
Biotic factors
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6.2 What is environment?
Biotic factors
Organisms living together interact in various ways
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6.3 Energy flow within an ecosystem
6.3
Energy flow
in ecosystem
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6.3 Energy flow within an ecosystem
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Feeds on
6.3 Energy flow within an ecosystem
Feeds on
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represent
A feeds on B
OR
6.3 Energy flow within an ecosystem
B feeds on A
?
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A feeds on B
6.3 Energy flow within an ecosystem
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Green plant produces food
Light energy is changed into chemical energy
6.3 Energy flow within an ecosystem
Supplies to other organisms
Producer
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Consumer
6.3 Energy flow within an ecosystem
They depend on other organisms for nutrition
Do snake rabbit produce their own food?
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Consumer
6.3 Energy flow within an ecosystem
Rabbit / organism feeds on producer
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Consumer
6.3 Energy flow within an ecosystem
Snake / organism feeds on primary consumer
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6.3 Energy flow within an ecosystem
along the food chain
to consumers
from producer
Rabbit
Energy is transferred
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6.3 Energy flow within an ecosystem
Food web
to form a
linked up together
Many food chains
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6.3 Energy flow within an ecosystem
How many food chains are there in this food web ?
Small bird
Lizard
Snail
Caterpillar
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6.3 Energy flow within an ecosystem
1
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6.3 Energy flow within an ecosystem
Small bird
Lizard
Snail
Caterpillar
1
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6.3 Energy flow within an ecosystem
Hawk
Small bird
Snail
2
Green plant
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6.3 Energy flow within an ecosystem
Small bird
Lizard
Snail
Caterpillar
1
2
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6.3 Energy flow within an ecosystem
Hawk
Hawk
Small bird
Snake
3
Snail
Green plant
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6.3 Energy flow within an ecosystem
Small bird
3
Lizard
Snail
Caterpillar
1
2
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6.3 Energy flow within an ecosystem
Hawk
Lizard
Caterpillar
Green plant
4
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6.3 Energy flow within an ecosystem
Small bird
3
Lizard
Snail
Caterpillar
1
2
4
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6.3 Energy flow within an ecosystem
Hawk
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Small bird
Lizard
Caterpillar
Green plant
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6.3 Energy flow within an ecosystem
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Small bird
3
Lizard
Snail
Caterpillar
1
2
4
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6.3 Energy flow within an ecosystem
Hawk
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Small bird
Snake
Lizard
Caterpillar
Green plant
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6.3 Energy flow within an ecosystem
There are 6 food chains in this food web.
6
5
Small bird
3
Lizard
Snail
Caterpillar
1
2
4
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6.3 Energy flow within an ecosystem
If they die, what will happen?
Simple inorganic compounds
Decomposers
Organic compounds
Green plant
Rabbit
Snake
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Decomposers
6.3 Energy flow within an ecosystem
Organic compounds of dead bodies or their wastes
Decomposition
Simple inorganic compounds
is absorbed by
Plant
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6.3 Energy flow within an ecosystem
Simple inorganic compounds
Fungi
Bacteria
Green plant
Rabbit
Snake
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6.3 Energy flow within an ecosystem
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6.3 Energy flow within an ecosystem
Pyramid of energy
Trophic level
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6.3 Energy flow within an ecosystem
Pyramid of energy
Trophic level
Type
Fourth
Third
Second
First
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6.3 Energy flow within an ecosystem
Pyramid of energy
When snake feeds on rabbit
e.g. Hair, skin may not be eaten
Removal of wastes
Food is oxidised to release energy. Some are lost
as heat.
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6.3 Energy flow within an ecosystem
Pyramid of energy
When food is transferred from one trophic level,
most energy is lost
because
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6.3 Energy flow within an ecosystem
Pyramid of energy
Secondary consumer
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6.3 Energy flow within an ecosystem
Pyramid of energy
Secondary consumer
The more levels in the food chains,
the less energy is available at the top consumers.
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6.3 Energy flow within an ecosystem
Pyramid of number
Secondary consumer
But
As we go up the pyramid,
the numbers of organisms USUALLY decrease.
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6.3 Energy flow within an ecosystem
Pyramid of number
Secondary consumer
But
producers
Why ?
In this case, the producer is a big tree.
That means it has a very large biomass
which is larger than the primary consumer.
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6.3 Energy flow within an ecosystem
Pyramid of number
The pyramid of numbers does not take into account
the relative size of the organisms
In this case, the producer is a big tree.
That means it has a very large biomass
which is larger than the primary consumer.
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6.3 Energy flow within an ecosystem
Pyramid of biomass
Biomass
If
Biomass
The energy it contained
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6.3 Energy flow within an ecosystem
Pyramid of biomass
Secondary consumer
As we go up the pyramid,
the biomass of organisms decreases.
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6.4 The accumulation of toxic substances along
food chains
6.4
Accumulation of
toxic substances
along food chains
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6.4 The accumulation of toxic substances along
food chains
Toxic substances
It cannot be destroyed or excreted
i.e. after entering into the body, they are
completely kept into organisms.
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6.4 The accumulation of toxic substances along
food chains
10 kg
Secondary consumer
toxic
1 g
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6.4 The accumulation of toxic substances along
food chains
10 kg
Secondary consumer
1 g
Concentration
0.001g / 1kg
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6.4 The accumulation of toxic substances along
food chains
10 kg
Secondary consumer
Concentration
0.01g / 1kg
1 g
After having the producers, the primary consumers
completely have all toxic substances.
Concentration
0.001g / 1kg
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6.4 The accumulation of toxic substances along
food chains
Concentration
10 kg
Secondary consumer
0.1g / 1kg
1 g
Concentration
0.01g / 1kg
After having the primary producers, the secondary
consumers completely have all toxic substances.
Concentration
0.001g / 1kg
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The toxic substances will be concentrated many
times along the food chain
Concentration
10 kg
Secondary consumer
0.1g / 1kg
1 g
Concentration
0.01g / 1kg
Concentration
0.001g / 1kg
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Example
6.4 The accumulation of toxic substances along
food chains
1600 ppm
DDT, pesticide sprayed by man onto the fields,
leaches to the water.
250 ppm
5 ppm
Water plant
0.02 ppm
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Example
6.4 The accumulation of toxic substances along
food chains
1600 ppm
250 ppm
DDT is absorbed by the water plants
5 ppm
Water plant
0.02 ppm
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Example
6.4 The accumulation of toxic substances along
food chains
Small fish eats a lot of water plants,
What will happen to a man if he joins this food
chain by eating the large fish?
1600 ppm
A large fish eats a lot of small fish,
A bird eats a lot of large fish.
DDT cannot be excreted or broken down
250 ppm
DDT will be concentrated many times along the
food chain
5 ppm
Water plant
0.02 ppm
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6.5 Cycling of materials
Cycling
6.5
Materials
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6.5 Cycling of materials
CO2 in air
Organic food
Carbon
Cycle
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Summary
6.5 Cycling of materials
By photosynthesis
Organic compound is formed
By feeding
Along the food chain
By respiration, decomposition, burning
Carbon dioxide is formed
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6.5 Cycling of materials
Nitrogen fixing bacteria
live in the root nodules of leguminous plant
N2 in air
Nitrogen fixation
can fix nitrogen gas from air into
nitrogenous compounds
Nitrogenous compounds
which is used by the plants to synthesise
Amino acids protein
amino acids protein
Cycle
Nitrogen
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6.5 Cycling of materials
Organic wastes dead bodies
Ammonia in soil
would be decomposed into
Decomposition
Putrefying bacteria
ammonia in soil
by putrefying bacteria
Amino acids protein in plant
Cycle
Nitrogen
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6.5 Cycling of materials
In the presence of O2
Nitrates in soil
ammonia is oxidised into
nitrites nitrates in soil
Nitrites in soil
Nitrification
by nitrifying bacteria
Nitrifying bacteria
O2
Ammonia in soil
Cycle
Nitrogen
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6.5 Cycling of materials
Nitrates in soil
Plants for protein synthesis
Nitrites in soil
Nitrification
Nitrifying bacteria
O2
Ammonia in soil
Cycle
Nitrogen
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6.5 Cycling of materials
In the absence of O2
Nitrates in soil
nitrates are changed into
Absence of O2
Denitrifying bacteria
nitrogen gas
Denitrification
by denitrifying bacteria
N2 in air
Cycle
Nitrogen
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6.5 Cycling of materials
N2 in air
Cycle
Nitrogen
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6.5 Cycling of materials
Under lightning
Nitrates
N2 reacts with O2
to form NO2
which dissolves into water to form nitrates
NO2
O2
N2 in air
Cycle
Nitrogen
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6.6 Ecological interdependence of organisms
6.6
Ecological
Interdependence
of organisms
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6.6 Ecological interdependence of organisms
Predation
Competition
Parasitism
5 relationships
Commensalism
Mutualism
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6.6 Ecological interdependence of organisms
Predation
Prey
Predator
B feeds on A
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6.6 Ecological interdependence of organisms
The following graph shows the relationship
between the numbers of predators preys.
Predation
prey
predator
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6.6 Ecological interdependence of organisms
Predation
prey
predator
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6.6 Ecological interdependence of organisms
Predation
prey
predator
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6.6 Ecological interdependence of organisms
Predation
prey
predator
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6.6 Ecological interdependence of organisms
Predation
prey
prey
predator
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6.6 Ecological interdependence of organisms
Predation
prey
predator
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6.6 Ecological interdependence of organisms
Competition
Both A and B feed on C (same requirement).
This requirement must be limited.
A and B compete to each other.
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6.6 Ecological interdependence of organisms
Organism A
Organism B
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6.6 Ecological interdependence of organisms
Organism A
Organism B
Host
Commensal
The commensal is benefited. The host is not
affected.
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6.6 Ecological interdependence of organisms
Commensalism
Organism A
Organism B
Host
Commensal
The commensal is benefited. The host is not
affected.
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6.6 Ecological interdependence of organisms
Parasitism Example
Crab
Barnacle
Barnacles live on the shell of the crabs.
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6.6 Ecological interdependence of organisms
Organism A
Organism B
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6.6 Ecological interdependence of organisms
Organism A
Organism B
Both obtain benefits from each other
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6.6 Ecological interdependence of organisms
Mutualism
Organism A
Organism B
Both obtain benefits from each other
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6.6 Ecological interdependence of organisms
Mutualism Example 1
Nitrogen fixing bacteria
Leguminous plant
Nitrogen fixing bacteria live in the root nodules
of leguminous plants
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6.6 Ecological interdependence of organisms
Mutualism Example 2
Fungi
Algae
lichen are the fungi algae living together.
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6.6 Ecological interdependence of organisms
Organism A
Organism B
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6.6 Ecological interdependence of organisms
Organism A
Organism B
Host
Parasite
Parasites gain benefits from the hosts. Hosts are
harmed.
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6.6 Ecological interdependence of organisms
Parasitism
Organism A
Organism B
Host
Parasite
Parasites gain benefits from the hosts. Hosts are
harmed.
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6.6 Ecological interdependence of organisms
Parasitism Example
Human
Tapeworm
Host
Parasite
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6.6 Ecological interdependence of organisms
1
Pr
Predation
2
3
Competition
Comp
5 relationships
Pa
Parasitism
4
Commensalism
Comm
Mutualism
Mu
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Summary
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materials that can be recycled in it
Mind Map
Ecosystem

1. carbon cycle

2. nitrogen cycle
a stable system with interaction between
energy flow within it can be represented by
made up of
organisms
environment
1. food web
food chains

2. pyramid of energy
consists of
same species living in the same habitat
components including
abiotic factors
biotic factors

3. pyramid of numbers
producers
populations
are
including

primary consumers

interaction of organisms in the habitat
1. temperature

4. pyramid of biomass
different groups form
2. light

secondary consumers

3. rainfall and humidity
including
community
1. predation

tertiary consumers
4. wind
2. competition
5. soil
decomposers
3. commensalism
6. pH
their positions are called
4. mutualism
trophic levels
5. parasitism
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