Transcript Food Chains & Energy Flow

Food Chains & Energy Flow
Food Chains vs. Food Webs
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Food chains show the path of food
from a producer to the final consumer
Food webs consist of interconnected
food chains
Food Chain
Food Web
Trophic Levels
•Primary consumers: (herbivores) feed directly on
producers
•Secondary consumers: (carnivores) feed on
primary consumers
•Tertiary consumers: feed on carnivores
Aquatic
Ecosystems
Terrestrial
Ecosystems
Food Chains
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Which are more
numerous in an
ecosystem:
producers or
consumers?
Producers are
always more
numerous than
consumers, why?
Energy Loss
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Of the energy that an organism consumes,
only a small fraction (ecological efficiency
of about 10%) is transferred to the next
trophic level
Where does that energy go?
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Most of the energy is lost as heat
That’s hot.
Drop it
like it’s
HOOOTT
“Rules” of Energy Pyramids
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Not everything in the lower levels
gets eaten
Not everything that is eaten is
digested
Energy is always being lost as
heat
House Analogy
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Just like how much
of the energy used
to heat a house is
wasted, much of
the energy used by
organisms is wasted
Efficiency Example
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Cars are only about 25%
efficient
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Only 25% of the total energy
in gasoline is used to make
cars move
What happens to the other
75%???
Energy Efficiency
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Why is it more energy efficient to eat
grains directly, rather than the meat of
grain-eating animals?
15 lbs. of feed
1 lb. of beef
Energy Efficiency
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Why is it more energy efficient to eat
grains directly, rather than the meat of
grain-eating animals?
6 lbs. of feed
1 lb. of pork
Energy Efficiency
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Why is it more energy efficient to eat
grains directly, rather than the meat of
grain-eating animals?
5 lbs. of feed
1 lb. of chicken
Energy Efficiency
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Why is it more energy efficient to eat
grains directly, rather than the meat of
grain-eating animals?
2 lbs. of feed
1 lb. of fish
Summary Question
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Why do food chains rarely have more
than 4 or 5 trophic levels?
Primary Productivity
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Gross primary productivity (GPP): the
rate at which an ecosystem's
producers convert solar energy into
chemical energy as biomass
Net primary productivity (NPP): the
rate at which energy for use by
consumers is stored in new biomass
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NPP = GPP – [rate producers use biomass]
Net Primary Productivity
Net Primary Productivity
The Food Chain RAP
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From the SUN ENERGY flows
Captured by plants this energy goes
CHLOROPHYLL and WATER plus CO2
Used in PHOTOSYNTHESIS to manufacture food
Plants get energy right from the sun
Making sugar for their food, a food chain has
begun
Plants are PRODUCERS, the first link in the chain
Animals eat these plants for energy is obtained
The Food Chain RAP
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Some can’t make food these are
CONSUMERS
They search for edibles this is no rumor
An animal like a mouse is the second
shackle
It’ll eat only plants but animals it won’t
tackle
The Food Chain RAP
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REFRAIN
OH OH OH
OH OH OH
OH OH OH
OH OH OH
PLEASE DON’T EAT ME!
PLEASE JUST LET ME BE
I’LL BE REAL GOOD
JUST DON’T MAKE ME FOOD
The Food Chain RAP
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Our mouse will nibble, on a plant as a treat
Mice don’t make food, only plants do this feat
Now this second link involves such a critter
Whose diet is plant material for lunch and dinner
The next animal could include a snake
Snakes are PREDATORS that sit and lie and wait
They’ll sit and stare with a watchful eye
Until a mouse comes passing by…
The Food Chain RAP
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REFRAIN
OH OH OH
OH OH OH
OH OH OH
OH OH OH
PLEASE DON’T EAT ME!
PLEASE JUST LET ME BE
I’LL BE REAL GOOD
JUST DON’T MAKE ME FOOD
The Food Chain RAP
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Now you gotta be quick you can’t be lazy
or this food chain will drive you crazy
You gotta be speedy you gotta be faster
to move too slow would be disaster
The snake had to act to stay alive
And that’s a fact it ain’t no jive
The snake will find food, and to its own dismay
Soon it too will become the PREY
The Food Chain RAP
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So the snake just feasted on the mouse
The snake better be careful he better look
out
Up in the air up in the sky
A hungry hawk is soaring by
The Food Chain RAP
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REFRAIN
OH OH OH
OH OH OH
OH OH OH
OH OH OH
PLEASE DON’T EAT ME!
PLEASE JUST LET ME BE
I’LL BE REAL GOOD
JUST DON’T MAKE ME FOOD
The Food Chain RAP
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On the snake the hawk will swoop
After it eats the hawk will poop
Who will clean up all this mess?
Here come the DECOMPOSERS at their best
If you’re a hawk you’ll eat a snake
A snake eats a mouse to stay in shape
A mouse eats some seeds and some grain
Put it together you have a FOOD CHAIN
The Food Chain RAP
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REFRAIN
OH OH OH
OH OH OH
OH OH OH
OH OH OH
PLEASE DON’T EAT ME!
PLEASE JUST LET ME BE
I’LL BE REAL GOOD
JUST DON’T MAKE ME FOOD