Transcript Ch 4 Ecology Powerpoint

Ch 3
Introduction to Ecology
Need to know
1. Define the term: biosphere, ecology,
ecosystem, habitat.
2. Name a range of ecosystems
3. Name examples of habitats.
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What is Ecology?
Ecology is the study of the interaction between
groups of organisms and their environment.
The environment consists of:
1. living e.g. availability of food &
2. non living parts e.g. amount of rainfall.
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1.4.2 Ecosystem
What is an Ecosystem?
An ecosystem is a community of organisms
and their environment.
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Diversity of Ecosystems
What is the Biosphere?
The biosphere is the part of the earth and its
atmosphere in which life can exist.
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Relationships
in the
biosphere
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Types of Organisms in an Ecosystem
• Producers – autotrophs: organisms that make
their own food.
• Consumers – heterotrophs: organisms that
can’t make their own food.
• Primary consumers – herbivores: animals
that eat plants only
• Secondary consumers – carnivores: animals
that eat animals & omnivores: animals that eat
plants & animals
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Learning check 1
1.
2.
3.
4.
5.
What is ecology?
What does the term environment refer to?
What is an Ecosystem?
What is the biosphere?
List the 4 types of Organisms that can be
found in an Ecosystem.
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Need to know
1. Distinguish between Abiotic & Biotic factors
2. Define and give examples of the following
as applied to terrestrial (land) and aquatic
(water) environments:
• Abiotic
• Biotic
• Climatic
• Edaphic factors
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Environmental factors that affect
organisms
There are two broad factors:
1. Biotic:
These are living factors e.g. the plants,
animals & decomposers.
These include:
i. competition
ii. predation
iii. symbiosis
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Biotic factors include:
1.
2.
3.
4.
5.
6.
7.
8.
Competitors
Predators
Parasites and pathogens
Decomposers
Humans
Pollinators
Prey
Plants for food and shelter
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Biotic Factors
Factor
Example
Food
The number of berries affects the number of
blackbirds.
The number of plankton affects the number of
mussels.
Competition Robins compete with each other for worms.
Barnacles and Limpets compete for space on the
rock.
Predation
Ladybirds reduce the number of greenfly.
The gull reduces the number of anemones.
Humans
Provide sanctuaries, protected areas
Pollution
Environmental factors that affect
organisms
2. Abiotic:
These are non-living factors.
They include:
I.Climatic factors - These are the average
weather conditions that affect the community in
an ecosystem
II.Edaphic Factors – related to the soil
III. Aquatic Factors
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Abiotic factors in a woodland
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Climatic factors include:
1.
2.
3.
4.
5.
Temperature
Rainfall
Humidity
Wind
Light intensity (including seasonal
variations)
6. Day length
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Edaphic factors include:
1.
2.
3.
4.
5.
6.
Soil type,
Soil pH,
Available (soil) water,
Air and Mineral content,
Humus,
Soil texture and Structure.
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Edaphic Factors
Factor
Effect
Soil
Type
Plants do not grow well in heavy soils due to lack of
oxygen.
Plants do not grow well in sandy soils due to leaching
of minerals
Soil pH
Moss and heathers prefer acid soils.
Most garden plants prefer neutral pH.
Birds foot trefoil prefers alkaline soil.
Soil
Plants need water for photosynthesis, transpiration
moisture and general metabolism.
Mineral
content
A lack of any mineral will affect the growth of the plant.
Aquatic Environmental
Factors
The following are also considered as factors:
• Light penetration
• Currents
• Wave action
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Abiotic Factors
Factor
Example
Altitude
Higher altitudes are wetter, cooler and windier than
lower altitudes.
Trees cannot live at high altitudes
Aspect
N facing slopes are cooler and darker than S facing
slopes.
Most plants grow on S facing slopes.
Plants and animals can be washed away. They
need to be able to attach to rocks e.g. seaweeds
Current
Exposure Organisms lose water when the tide is out. There is
a need for a shell or mucilage to retain water.
Learning check 2
1. What are the two broad environmental
factors that affect organisms?
2. What are biotic factors?
3. What is meant by abiotic factors?
4. What are climatic factors?
5. What are edaphic factors?
6. What are aquatic factors?
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1.4.6 Energy Flow
Need to know
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.
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Energy Flow in an Ecosystem
The sun is the primary source of energy for life
on our planet.
Energy is transferred from one organism to the
next in an ecosystem due to feeding, e.g. along
a food chain.
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Food Chain
Is the feeding relationship between organisms
through which energy is transferred.
A food chain ends when there is not enough
energy to support another organism.
grass  rabbit  fox.
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A Grazing food chain
is one which begins with a plant.
Grass  grasshoppers  frogs  hawks
Honeysuckle  aphids  ladybirds 
thrushes
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A Detritus food chain
is one which begins with dead organic matter
and animal waste (detritus).
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Food Web
Consists of two or more interconnecting 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?
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Producers
Producers are organisms capable of making
their own food by photosynthesis, e.g. green
plants.
Food chains always begin with Primary
producers
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Consumers
Consumers are organisms that feed on other
organisms. They cannot make their own food.
There are three types:
1.Primary consumers – feed on producers
2.Secondary consumers – feed on primary
consumers
3.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 3
1. Construct 2 simple food chains
E.g.
Plant  caterpillar  thrush  fox
Plant  earthworm  blackbird  fox
2. Combine them to form a food web
E.g.
Caterpillar
Thrush
Fox
Plant
Earthworm
Blackbird
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Trophic Level
Is the feeding level in a food chain.
1. Plants are at the 1st trophic level (T1) and
2. Herbivores occupy the 2nd trophic level (T2).
3. Carnivores that eat herbivores are at the 3rd
trophic level (T3).
4. The 4th trophic level (T4) is often occupied
by the top carnivore.
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Trophic levels
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Learning check 4
1. What is the primary source of energy?
2. Energy flow/transfer through an ecosystem is
achieved by …
3. What is meant by a Grazing food chain?
4. Give an example
5. Explain the following terms: Producer,
Consumer, Primary Consumer, Secondary
Consumer & Tertiary Consumer
6. What is meant by trophic level?
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Pyramid of Numbers
Need to know
• Construct a pyramid of numbers.
• Explain the limitations of use regarding the
size of organisms
• State two inferences (conclusions) that can
be made regarding the shape of the pyramid
e.g. large tree or parasites
• Explain the energy loss shown in the
pyramid
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Pyramid of Numbers
Is used to show the numbers of organisms at
each trophic level in a food chain.
Fox
Rabbits
Grasses
• Bottom layer is the usually the largest and
represents the number of primary producers
• The next layer is usually smaller and
represents the primary consumers
• The next layer – the no. of secondary
consumers
• The uppermost layer - the no. of tertiary
consumer, where there may be only one.
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Energy Loss in a Food Chain
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Energy loss in a Food Chain or
Ecosystem
• From the previous slide we can see when a
plant is eaten only 10% of the energy it
absorbed from the sun is transferred onto the
herbivore.
• The herbivore uses up 90% of this energy
during respiration, as heat & only passes on
10% to the secondary consumer.
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• This continues up the food chain, so that at
each trophic level, the organisms only pass
on 10% of energy that they have received.
• Each trophic level contains less energy than
the previous one.
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The large energy loss from one trophic level to
the next explains why
1. food chains contain no more than four or
five levels
2. the number of organisms declines as you
go up the pyramid
3. the body size of animals increase as you
go up the pyramid, as predators need to be
larger than their prey.
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ENERGY FLOW
LOST
1%
99
%
10%
SEAWEED
SHRIMP
LOST
90%
10%
10%
SEA
ANENOME
LOST
90%
GULL
LOST
90%
Energy Transfer
This is the flow of energy into the
ecosystem from the sun; and within the
ecosystem through the different trophic
levels along food chains, and finally out of
the ecosystem into the atmosphere as
heat loss due to respiration.
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Energy transfer through an ecosystem
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To construct a pyramid of numbers
1. Count the primary producers and place them
at the base of the pyramid
2. Count each consumer and include them
according to their status (primary or
secondary consumer) in the pyramid
3. The apex of the pyramid should include
tertiary or top carnivores
4. Draw the pyramid so that the area/volume of
each level is proportional to the number of
organisms found
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Pyramid of Numbers
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Normal Pyramid of Numbers
A reminder of what a pyramid of numbers looks
like
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Limitations of use
1. An inverted pyramid – numbers are considered
.
2. a distorted pyramid – pyramids involving
numerous parasites.
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An inverted Pyramid of Numbers
When organism size is not considered,
but number of organisms is, an inverted
pyramid occurs e.g. one rose bush can
support thousands of greenfly.
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A distorted Pyramid of Numbers
A similar problem arises with parasites –
numerous parasites on one host – resulting
in a distorted pyramid
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YouTube - Food Chains
• Song
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Learning check 5
1. What are Pyramids of Numbers used for?
2. Can you explain the energy loss through an
ecosystem?
3. Can you explain why pyramids of numbers
don’t always have the same size.
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A habitat
• A habitat is the place an organism lives
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1.4.7 Niche
Need to know
Explain the term niche and give examples.
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Niche
A niche is the functional role of an organism in
an ecosystem.
A niche is a term describing the relational
position of a species or population in an
ecosystem.
The abiotic (non-living) or physical environment
is part of the niche because it influences how
populations affect, and are affected by,
resources and enemies.
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This includes how a population responds to
the abundance of its resources and enemies
(e.g. by growing when resources are abundant,
and predators, parasites and pathogens are
scarce)
and how it affects those same factors (e.g. by
reducing the abundance of resources through
consumption and contributing to the population
growth of enemies by falling prey to them).
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No two species can occupy the same niche in
the same environment for a long time.
When plants and animals are introduced into a
new environment, they can occupy new niches
or niches of native organisms, outcompete
the native species, and become a serious
pest.
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Learning Check 6
1. What is meant by a niche?
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1.4.8 Nutrient Recycling
Need to know
Define the term: nutrient recycling by organisms.
1. Outline and draw the Carbon Cycle.
2. Outline and draw the Nitrogen Cycle.
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Nutrient Recycling
Minerals / nutrients such as:
1. Carbon
2. Nitrogen
found in plants and animals are continously
recycled in the environment when they die.
Organisms / decomposers bacteria and fungi
break down the remains and release the
nutrients back into the environment. which are
taken up by other plants and used to make new
organic material.
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Carbon Cycle
Carbon forms part of all organic nutrients –
carbohydrates, fats and proteins.
1.Plants remove C02 from the environment
during photosynthesis
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2. Carbon dioxide is returned to the
environment by:
– Respiration in plants, animals & microorganisms.
– Combustion i.e. burning fossil fuels
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The Carbon Cycle
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Summary of Carbon Cycle
The carbon cycle
The-carbon-cycle
teachertube - carbon cycle drawn
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• The Carbon Cycle Song
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• Carbon Cycle Rap
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The Nitrogen Cycle
All organisms need nitrogen for protein, DNA &
RNA manufacture
78% of the Earth’s atmosphere is nitrogen gas,
but it cannot be used in this form by plants and
animals.
There are 5 stages:
1.Nitrogen Fixation
2.Absorption
3.Decomposition
4.Nitrification
5.Denitrification
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1. Nitrogen Fixation
•
•
Nitrogen-fixing bacteria that live in the soil /
root nodules (swellings) of certain plants
convert N2 gas in the air into Nitrates.
Lightening storms and fuel burning in car
engines produce nitrates, which are washed
by rain into the soil water.
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2. Absorption
• Plants absorb the Nitrates and convert them
into plant protein
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3. Decomposition
• When organisms die, their proteins are
converted to ammonia by bacterial
decomposition.
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4. Nitrification
• Nitrifying bacteria in the soil convert
2_
ammonia (NH3) into
nitrites (NO2 ) and then
_
into nitrates (NO3 ).
• Nitrates can then be absorbed by plants to
continue the cycle.
• The Nitrogen cycle
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5. Denitrification
• Denitrifying bacteria convert soil nitrates into
N2 gas, which is released into the atmosphere.
• The Nitrogen cycle drawn
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The Nitrogen Cycle
Summary of Nitrogen Cycle
The nitrogen cycle 15mins
The -nitrogen-cycle 3mins
http://www.schooltube.com/video/11297b97b
6406af0151e/The-Nitrogen-Cycle
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Summary of Nitrogen Cycle
Nitrogen
in Air
1
Nitrite
NO2
6
7
8
5
Ammonia
NH3
4
5
Nitrate in
Soil NO3
2
Plant Protein
1. Nitrogen Fixation &
Lightning
2. Absorbed by roots and
used by plants –
Assimilation
3. Animal feeding, digestion
& assimilation
4. Excretion: urea 
Ammonia
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Animal Protein
5. Death &
decomposition –
putrefying bacteria
6. Nitrification: NH3 
NO2
7. Nitrification: NO2 
NO3
8. Denitrification: NO3 
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NO2  N
Learning check 5
1. What is meant by nutrient recycling?
2. What process(es) remove Carbon dioxide
from the atmosphere?
3. What process(es) add Carbon dioxide to the
atmosphere?
4. Nitrogen gas must be ‘fixed’ – what does this
mean?
5. In what form is nitrogen absorbed by plants?
6. What is nitrification?
7. What do denitrifying bacteria do?
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YouTube - Mercy Mercy Me
(The Ecology Song)
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END
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