Transcript SUSTAINING ECOSYSTEMS - Halton District School Board

Energy in Food Chains
B. ENERGY: THERMODYNAMICS
Living things and the cells that make them up must follow the
laws of thermodynamics. Cells take energy and convert it into
different forms.Important principles in biology that govern the
chemical process of metabolism

1st Law

energy can neither be created nor destroyed it
merely changes form
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
solar  chemical  mechanical  heat
2nd Law
every
time energy changes form some energy is
lost as “waste” or useless energy in the form of
heat (less energy at the end of the transfer than at the beginning)
ENERGY: THE SUN


source of all energy for living organisms
absorbed or reflected by:
gases
in the air
water (clouds, ice, lakes, etc…)
rocks and soil
living organisms

photosynthesis
collect
solar energy
convert to chemical energy (food)
ENERGY: PHOTOSYNTHESIS



green plants (some single celled organisms)
collect sunlight using a green pigment called
chlorophyll
plants convert light, CO2 and water to glucose
(sugar)
plants serves as the origin of food for all other
organisms:
indirectly from other animals (carnivores) eating the herbivores
directly from herbivores eating green plants
ENERGY IN FOOD CHAINS
energy passed to consumer
producer 10% primary (1o)
consumer
90%
10% secondary (2o)
consumer
90%
energy used to live
10% Rule:
only 10% of the energy in an organism is stored and passed on to
the next trophic level (90% of the energy is used to live).
ENERGY IN ECOSYSTEMS & TROPHIC LEVELS
The term trophic level describes the place in a food chain
that an organism feeds
1st TROPHIC LEVEL
• producers or autotrophs that feed themselves
2nd TROPHIC LEVEL
herbivores or primary [1o] consumers that eat producers
3rd TROPHIC LEVEL
carnivores or secondary [2o] consumers that eat
herbivores
4th TROPHIC LEVEL
carnivore or tertiary [3o] consumers that generally eat
other carnivores
All consumers are called heterotrophs.
All producers are called autotrophs
A food web is a series of interconnected food chains
HAWK
BOBCAT
WEASEL
FROG
MOUSE
GRASSHOPPER
SEEDS
GRASS
VOLE
BACTERIA
FALLEN LEAVES
HAWK
BOBCAT
WEASEL
FROG
MOUSE
GRASSHOPPER
SEEDS
GRASS
VOLE
BACTERIA
FALLEN LEAVES
Identify an autotroph produces its own food
Identify a primary consumer eats a producer (herbivore)
HAWK
BOBCAT
WEASEL
FROG 2o consumer
MOUSE
GRASSHOPPER
o
VOLE 1 consumer
BACTERIA
SEEDS
producer
GRASS
FALLEN LEAVES
Identify a secondary consumer
a carnivore that eats other herbivores
HAWK
BOBCAT
WEASEL
FROG
MOUSE
GRASSHOPPER
SEEDS
GRASS
VOLE
BACTERIA
FALLEN LEAVES
Identify an organism at the fourth trophic level
HAWK
BOBCAT
WEASEL
FROG
MOUSE
GRASSHOPPER
SEEDS
GRASS
VOLE
BACTERIA
FALLEN LEAVES
Identify a decomposer something that eats dead things
Identify an omnivore something that eats plants & animals
HAWK
BOBCAT
WEASEL
FROG
MOUSE
GRASSHOPPER
SEEDS
GRASS
VOLE
FALLEN LEAVES
Explain what would be the effect on voles of fewer hawks
 hawks =  weasels and  mice
 mice & weasels =  grasshoppers
 grasshoppers =  grass
 grass =  food for voles =  voles
BACTERIA
HAWK
BOBCAT
WEASEL
FROG
MOUSE
GRASSHOPPER
VOLE
BACTERIA
GRASS
FALLEN LEAVES
SEEDS
Explain what would be the effect on bobcats of fewer grasshoppers
OVER THE SHORT TERM
grasshoppers =  grass & seeds =  food for frog, weasels & mice
 food for frogs means frogs leave or die
 frogs means less food for bobcats =   bobcats
OVER THE LONG TERM
grass = more food for voles =  voles
 voles = more food for bobcats =  bobcats
HAWK
BOBCAT
WEASEL
FROG
MOUSE
GRASSHOPPER
SEEDS
VOLE
GRASS
BACTERIA
FALLEN LEAVES
Explain, what would be the effect on grasshoppers of fewer leaves
OVER THE SHORT TERM
 fallen leaves =  food for voles
OVER THE LONG TERM
 food means some voles leave
 voles =  food for bobcat
voles now eat more grass
 grass for grasshoppers =  grasshoppers
(they die off/ or leave area as less food)
bobcats now eat more frogs
 frogs = weasels eat more grasshoppers
 fewer grasshoppers
HAWK
BOBCAT
WEASEL
FROG
MOUSE
GRASSHOPPER
SEEDS
GRASS
VOLE
BACTERIA
FALLEN LEAVES
Explain what would be the effect on hawk of fewer bobcats.
OVER THE SHORT TERM
OVER THE LONG TERM
 bobcats =  voles and frogs
 voles eat more grass =  grass
 frogs =  food for weasels
 grass for grasshoppers & mice
some weasels leave or die off =  food for hawks  grasshoppers & mice
= fewer hawks
=  food for hawks  fewer hawks