ecology 3 - food chains webs energy transfer
TRANSCRIPT
7/27/2019 Ecology 3 - Food Chains Webs Energy Transfer
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ECOLOGY
Food Chains,
Food Webs &
Energy Transfer
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Lesson Outline• Food Chains
• Food Webs• Energy Transfer
• Carbon Cycle
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Food chains
• A food chain shows the feeding
relationship among a series of organisms
through which energy is transferred in the
form of food.
• It always starts with a primary producer
and ends with a consumer .
• Each level or step in a food chain is called
a trophic level.
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Food chains
1. Plants are the primary producers
• use light energy from the sun toproduce food (sugar) from carbon
dioxide and water
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Food chains
2. Animals are the consumers
• Herbivores (primary consumers)
• Carnivores that eat herbivores(secondary consumers)
• Carnivores that eat other carnivores(tertiary consumers)
• Omnivores eat both plants & animals• Scavengers feed on dead animals
e.g. vultures
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Food chains
3. Decomposers breakdown deadorganisms
• releases mineral salts back into the
food chain for plants as nutrients• Bacteria, fungi
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Food Chain –
Trophic Level• Each step/level in a food chain or food web
is known as a trophic level.
• Sequential from producer to primary
consumer to secondary consumer to
tertiary consumer.
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Producer Primary
Consumer
Secondary
Consumer
Tertiary
Consumer
green plant grasshopper spider bird
Food Chain
Trophic
level 1
Trophic
level 2
Trophic
level 3
Trophic
level 4
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Food webs• Most animals eat more than one kind of
food in order to meet their food and energy
requirements.
• A food web is several
food chains connected
together .
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green plant
aphid
grasshopper spider bird
caterpillar
Food Web
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green plant
aphid
grasshopper spider bird
caterpillar
Food Web
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green plant
aphid ladybird
grasshopper spider bird
caterpillar
Food Web
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Food web
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Food Web-sitesFood chain BrainPOP video
• http://magma.nationalgeographic.com/ngex
plorer/0309/quickflicks/index.html
Food chain crossword puzzle
• https://reader009.{domain}/reader009/html5/04
puzzle.htm
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1
Sun (light
energy)
1. In any
ecosystem, the
ultimate source of
energy is the sun.
Energy flow
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1
2
Sun (light
energy)
photosynthesis
Producers (Green plants)
Energy flow
2. Light energy
absorbed bychlorophyll in
producers is
converted into
chemicalenergy during
photosynthesis.
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1
2
3
3
4
4
4
5
5
Sun (light
energy)
photosynthesis
feeding
feeding
respiration
respiration
respiration
excretion
excretion
egestion
egestion
Secondary
consumers
(carnivores)
Primary consumers
(Herbivores)
Producers (Green plants)
Energy flow
5. Energy is also lost
through faeces, excretory
waste and dead organisms.
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1
2
3
3
4
4
4
5
5
Sun (light
energy)
faeces and excretory products
+ dead bodies of organisms
decomposition
photosynthesis
feeding
(holozoic nutrition)
feeding
respiration
respiration
respiration
excretion
excretion
egestion
egestion
Secondary
consumers
(carnivores)
Primary consumers
(Herbivores)
Producers (Green plants)• Decomposers break down dead
organic matter and use some of
this trapped chemical energy for
their own needs.
Energy flow
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1
2
3
3
4
4
4
5
5
Sun (light
energy)
faeces and excretory products
+ dead bodies of organisms
decomposition
heat released to environment
photosynthesis
feeding
feeding
respiration
respiration
respiration
excretion
excretion
egestion
egestion
Secondary
consumers
(carnivores)
Primary consumers
(Herbivores)
Producers (Green plants)Some heat is also lost to theenvironment during
decomposition.
Energy flow
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1
2
3
3
4
4
4
5
5
+ CO2
Sun (light
energy)
faeces and excretory products
+ dead bodies of organisms
decomposition
heat released to environment
photosynthesis
feeding
feeding
respiration
respiration
respiration
excretion
excretion
egestion
egestion
Secondary
consumers
(carnivores)
Primary consumers
(Herbivores)
Producers (Green plants)
Energy flow
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1
2
3
3
4
4
4
5
5
+ CO2CO2 Sun (light
energy)
faeces and excretory products
+ dead bodies of organisms
decomposition
heat released to environment
photosynthesis
feeding
feeding
respiration
respiration
respiration
excretion
excretion
egestion
egestion
energy lost in uneaten body
parts, faeces and excretory
products (usable energy)
heat lost to
environment
heat lost to
environment
Secondary
consumers
(carnivores)
Primary consumers
(Herbivores)
Producers (Green plants)
Energy flow
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Energy flow• Energy flows from one trophic level to
another.
• The flow is non-cyclic as it does not return
to the organism which released it.
• It is lost mainly as heat.
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Why are shorter food chains
more efficient than long foodchains?• Since energy is lost at each trophic level, less
and less energy is available for the organism atthe next level
• A shorter food chain means more energy isavailable to the final consumer because less
energy is lost to the environment• Most food chains have not more than 5 trophic
levels
Discuss with
your partner!
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Energy flow• about 10% of light energy from the Sun is
stored in the plant tissues.
• If an animal eats the plant, only 10% of this
is used to build new animal tissues.
• The rest is used by the animal to stay alive,
keep warm and move about, and some islost in its faeces and urine.
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Energy flow• Thus from one trophic level to another:
–Only 10% of the energy is transferred.
–Remaining 90% is lost.
• 10% is used to build new cell matter and
stored.
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Energy flow
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Energy flow1. Energy lost as heat to the environment
during respiration
2. Energy lost in faeces and excretory
products
3. Energy lost in dead organisms
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Carbon Cycle• Carbon, oxygen, nitrogen & water are
essential nutrients for life.
• Nutrients are not lost to the environment
but are recycled instead.
• Nutrients are finite and thus, must be
recycled.
• Carbon cycle used as an example.http://www.epa.gov/climatechange/kids/movies/carbon_cycle_version
2.swf
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Carbon Cycle
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Carbon Cycle• Photosynthesis:Carbon dioxide + water glucose + oxygen + water
Light energy
chlorophyll
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Carbon CycleRelease of CO2 into the environment:
• Respiration of living organisms
• Combustion of fossils fuels
• Decay of dead organisms
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Carbon Cycle Absorption of CO2 from the environment:
• Photosynthesis
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Carbon Cycle• The cycle plays an important role in
maintaining a balanced amount of carbon
dioxide in the atmosphere.• What would upset this balance?
• What are some of the effects of such an
imbalance?
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References• http://warnell.forestry.uga.edu/warnell/kahrs/h/habitats.html
• http://www.sheppardsoftware.com/content/animals/kidscorner/foodch
ain/producersconsumers.htm
• http://www.geographyalltheway.com/ib_geography/ib_ecosystems/imagesetc/food_web_300.gif
• http://www.epa.gov/climatechange/kids/movies/carbon_cycle_version
2.swf
• http://ez002.k12.sd.us/Chapter%20Two%20Science.htm
• http://www.ebi.ac.uk/2can/biology/organisms4.html