Ecology
Objectives
1. To study new vocabulary associated with
ecology i.e. ecology, biosphere, ecosystem,
habitat, population, community
2. To outline the types of ecosystem available e.g.
desert, rainforest, marine, grassland
3. To study one ecosystem in detail
4. To examine environmental factors that affect
organisms
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Objectives
Name the sun as the primary source of energy.
Name feeding as the pathway of energy flow.
Present a grazing food chain.
Present a food web.
Construct a pyramid of numbers.
Investigate how the Carbon cycle and the Nitrogen
cycle operate
Examine the human impact on an ecosystem
Study how pollution occurs
Define conservation and examine one conservation
practice
Study waste management in agriculture, fisheries and
forestry
Investigate how waste production can be controlled.
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Some Ecology Definitions
Ecology is the study of interactions between living things and
their environment.
Biosphere is the part of the planet containing living things.
Ecosystem a group of organisms that interact with their
environment together.
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Habitat the place an animal or plant lives.
Population members of the same species living in
an area.
Community all the different populations (species)
in an area.
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Environmental Factors
Biotic factors living factors.
Examples Food, competition,etc.
Abiotic factors non-living factors.
Examples Altitude, Aspect
Climatic factors weather over a long time.
Examples Temperature, rainfall
Edaphic Factors Factors to do with soil.
Examples pH, water content
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What is an ecosystem?
A community of living organisms interacting
with one another and their non-living
environment within a particular area, e.g.
woodland, etc.
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Energy Flow
Ecosystems are unable to function unless
there is a constant input of energy from an
external source.
Where does this energy come from?
The Sun
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Energy Flow
This is the pathway of energy transfer from
one organism to the next in an ecosystem
due to feeding, e.g. along a food chain
Feeding allows energy to flow from one
organism to another in an ecosystem.
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Energy Flow
Plants catch the energy and change it into
sugars.
The plants are then eaten by consumers.
These consumers get around 10% of the
energy from the plant.
If these consumers are eaten they pass on
about 10% of their energy.
Food chains can only be a certain length as
the energy eventually runs out.
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Energy flow in the ecosystem
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Food Chain
Is a flow diagram that begins with a plant and
shows how food/energy is passed through a
series of organisms in a community.
Each organism feeds on the one before it.
A food chain ends when there is not enough
energy to support another organism.
An example of a food chain:
grass  rabbit  fox.
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Learning check
What is meant by primary source?
Main source
What is the primary source of energy?
The sun
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Grazing food chain
A grazing food chain is one where the initial plant
is living e.g.
Grass  grasshoppers  frogs  hawks
Honeysuckle  aphids  ladybirds  thrushes
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A Detritus food chain
A detritus food chain is one where the chain begins
with dead organic matter and animal waste
(detritus) e.g.
Fallen leaves  earthworms  blackbirds  hawks
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Detritus Food Chain
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Food Web
A food web shows all the feeding connections
in the habitat/ecosystem.
Constructed by showing the links between
all the interconnecting food chains in the
habitat.
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Food Web
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Food Web
a) Name a producer?
b) Name a primary consumer?
c) Name a secondary consumer?
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Learning check
Draw a woodland food web constructed using
at least two food chains.
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A woodland food web
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Construct a two food chains (4 ‘links’) from the above food web
Another food web
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What is the longest food chain you can construct from this food web?
Learning check
What is meant by a Grazing food chain?
• is a food chain where the initial plant is
living
Give an example
1.
2.
Grass  grasshoppers  frogs  hawks
Honeysuckle  aphids  ladybirds  thrushes
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Producers
Producers are organisms capable of making
their own food by photosynthesis, e.g. green
plants.
Primary producers are the first members of
a food chain
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Consumers
Consumers are organisms that feed on other
organisms. They cannot make their own
food. There are three types:
• Primary consumers – feed on producers
• Secondary consumers – feed on primary
consumers
• Tertiary consumers – feed on secondary
consumers
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Woodland food chain
Honeysuckle  aphids  ladybirds  thrushes
Producer
Primary
consumer
Secondary
consumer
Tertiary
consumer
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Learning check
Construct a simple food web
Two food chains e.g.
Plant  caterpillar  thrush  fox
Plant  earthworm  blackbird  fox
Combine them to form a food web
dandlion
Caterpillar
Thrush
Earthworm
Blackbird
Fox
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Trophic Level
Trophic Level refers to the position of an
organism in a food chain.
Plants are at the 1st trophic level (T1) and
Herbivores occupy the 2nd trophic level (T2).
Carnivores that eat herbivores are at the 3rd
trophic level (T3).
The 4th trophic level (T4) is often occupied by
the top carnivore.
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Trophic levels
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Pyramid of Numbers
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Inverted Pyramid of Numbers
This is where the number of
organisms actually increases.
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Learning check
Explain the following terms:
• Producer
• organism capable of making its own food by photosynthesis
• Consumer
• organism that feeds on other organisms – cannot make their own food
• Primary Consumer
• organism that feeds on producers
• Secondary Consumer
• organism that feeds on primary consumers
• Tertiary Consumer
• organism that feeds on secondary consumers
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Learning check
What is meant by trophic level?
This refers to the position of an organism in a
food chain.
T1 = 1st trophic level = Plants
T2 = 2nd trophic level = Herbivores
T3 = 3rd trophic level = Carnivores
T4 = 4th trophic level = (T4) Top Carnivore.
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Ecological Niche
Ecological niche is the role an organism plays
in the community.
Two organisms with the same niche must compete
with each other.
e.g. magpies eat from gutters. Swallows eat in
flight and thrushes eat at ground level.
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Nutrient Recycling
Carbon is recycled in nature. This is the Carbon Cycle.
Plants take in carbon dioxide and make wood. When they die
they release the carbon dioxide.
Animals are made of carbon.
We get carbon from eating plants and other animals.
Microorganisms, like fungi and bacteria return carbon dioxide
to the air by decomposing dead plants and animals.
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Carbon Cycle
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Three groups of organisms have roles in the
carbon cycle
1. Plants remove carbon dioxide from
environment through photosynthesis and
return it by respiration
2. Animals obtain carbon by eating plants and
return it to the air as carbon dioxide in
respiration
3. Micro-organisms return carbon to the air as
a result of breakdown of animals and
plants
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Nitrogen Cycle
Nitrogen is the most abundant gas in air. It takes up 79% of the
atmosphere.
The Nitrogen is taken out of the air by Nitrogenfixing bacteria.
The bacteria live on the roots of plants.
They get food from the plants and they give
the plants Nitrates. Without these bacteria
no plants would grow.
This relationship is called symbiotic as
both organisms benefit.
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Definitions
Nitrogen Fixation is the conversion of nitrogen
gas into ammonia (NH3), ammonium (NH4+) or
nitrate (NO3-)
Nitrification is the conversion of ammonia and
ammonium (NH4+) compounds to nitrite and then
to nitrate.
Denitrification is the conversion of nitrates to
nitrogen gas.
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Nitrogen Fixing Bacteria
Nitrogen fixing bacteria can be found free
in the soil or maybe associated with the
roots of certain plants e.g. Legumes.
Legumes include clover, soya bean and
peas.
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Global Warming
Since the 1970's Scientists have realised that the world's carbon
dioxide % has been increasing.
CO2 is produced mostly from burning fossil fuels.
In the atmosphere carbon dioxide traps heat and warms up the
planet. That's why it is called global warming.
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Effects of Global Warming:
1.Warming oceans store the heat and ocean currents
change.
2. When the currents heat and change they also
Change the wind and rain patterns.
This causes floods and droughts, stronger
hurricanes and storms in different places.
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Pollution
Pollution is any harmful addition to the environment.
Pollutants are substances that cause pollution.
Types of pollution
1. Domestic pollution from houses
2. Agricultural pollution sprays, slurry on fields
and in rivers
3. Industrial pollution smoke
and fumes, acid rain
Etc
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Ozone
Ozone depletion is an example of air pollution.
Ozone (O3) is a gas that absorbs harmful
ultraviolet (UV) light.
A hole was first noticed in 1984 over
Antarctica.
There is also a hole at the Arctic, Australia and
sometimes over Europe.
Ozone loss is caused by, CFCs
(ChloroFluroCarbons) in aerosols,
freon gas in fridges and others
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A decrease in Ozone causes skin cancers, damage to crops,
damage to animals and plankton reduction which affects birds, fish, whales and oxygen levels.
Control of Ozone loss CFCs are now banned and
fridges are recycled carefully and not just dumped.
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Conservation
Conservation is the wise management of our
existing natural resources.
We use natural resources everyday and in
some cases we exploit these natural
resources.
e.g. over fishing from the sea and growing
plant species where they would not
normally grow.
The responsibility lies with individuals and
big organisations to exercise control to
prevent damage to habitats e.g.
rainforests.
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Extinction
Amphibians
Natterjack Toad
The present rate of extinction is higher than at
any time in the earths history. We have a duty Common Frog
to future generations to pass on the natural
Common Newt
environment we have inherited.
Reptiles
Endangered species in Ireland:
Common Lizard
Leatherback turtle
Mammals
Invertebrates
Badger, All Bat species, All Deer species Freshwater crayfish
Hare species, Hedgehog, Otter
Freshwater pearl
mussel
Pine Marten, Red Squirrel, Dolphin
Kerry slug
species
Porpoise species, Seal species, Whale
species
Pygmy Shrew,Stoat
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Benefits of Conservation
1. Prevents organisms from becoming extinct.
2. Maintains the balance of nature
3. Maintains a wide range of living things.
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Examples of conservation
• National parks
• Hedgerow and bogland conservation
• Listing of threatened species e.g. lizard, frog and stoat in
Ireland
• Zoos and wildlife parks – by breeding endangered species
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You are required to study the effects and
control of any one pollutant for Leaving
Cert. from either fisheries, agriculture or
forestry.
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Conservation Practice from Fisheries
a) Pollution of rivers, lakes and sea that kill
fish – once depleted fish stocks take a long
time to replace
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b) Over fishing has reduced (and in some
cases wiped out) fish stocks at sea. For this
reason fish quotas (weight of each species
of fish) have been imposed in many
countries to try and ensure that enough fish
are left in the sea to replenish stocks.
c) Use of small mesh nets can result in too
many young fish being caught which will
reduce fish stocks.
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Examples of conservation in fishing:
1. Size of mesh in nets is very important so
only larger older fish are caught
2. Removal of pollution is very important so
fish stocks are maintained.
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Waste Management
Modern living produces large amounts of
waste e.g. household rubbish.
Important to manage this waste to prevent
pollution and conserve environment.
Lets look at waste management in:
a) Agriculture
b) Fisheries
c) Forestry
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a. Agriculture
Slurry (liquidified waste from farm animals)
often pollutes lakes and rivers. Slurry
contains high levels of minerals e.g.
phosphorus and nitrogen. These minerals
cause increased growth of algae in rivers and
lakes causing algal blooms.
When algae die they are decomposed by bacteria
and the bacteria use
up the oxygen in the water causing
fish to die.
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Addition of nutrients to fresh water is called
eutrophication.
We can reduced the amount of slurry getting
into fresh water by:
1. Storing slurry in leak proof pits
2. Spreading slurry on dry land in summer
rather than on rainy days.
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2. Fisheries
When fish are processed waste materials e.g.
heads, tails, blood etc. are neutralised by
adding formic acid and then pulped, dried
and recycled as fertilisers or pig feed.
3. Forestry
Waste materials include sawdust, small
branches etc. Small branches can be spread
on the forest floor to help machinery move
more easily. These branches decay and add
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nutrient back into the soil.
Problems associated with waste disposal
1. Toxic chemicals released from wastes can
contaminate water.
2. Waste disposed of in landfill sites can be
unsightly and attract rats.
Role of micro-organisms in waste management
and pollution control
1. Landfill sites: Bacteria and fungi breakdown the organic
waste.
2. Sewage: a) Primary sewage treatment involves physically
screening waste and allowing it to settle. This removes large
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objects and solids.
b) Secondary treatment:Occurs when waste is
broken down by bacteria and fungi. The
waste is aerated to allow breakdown to
occur. Secondary Treatment breaks down
most of the organic matter.
c) Tertiary treatment: Sometimes used to
remove minerals e.g. phosphate and
nitrates.
Control of Waste Production
“Reduce Reuse Recycle”
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Reduce – Reduce your waste production by reducing
your consumption of products you don’t really need.
Reuse – Some things can be reused e.g. glass bottles
can be re-used up to 40 times.
Recycle – Many items can be recycled e.g. paper and
plastic.
Up to 40% of household waste is organic material that
can be broken down by bacteria and earthworms to
form compost. This compost can be added to soil to
help plants grow.
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2012 Paper > Section A > Question 4
Solutions
2012 Paper > Section C > Question 11