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Living Things!
Factors that affect living things are:
• Biotic factors – things that are alive or were alive (other organisms)
• Abiotic factors – things that are non-living (temperature, water etc.)
• The interaction of all biotic and abiotic factors creates an ecosystem.
Roles of Organisms
All living things need energy to survive and grow. The source of
this energy is the sun.
Plants are autotrophs and through photosynthesis (an
endothermic process) create food (sugar), to store energy for
later use.
To release stored energy from the sugar the plants carry out
respiration ( an exothermic process).
Not all organisms can produce their own food , so some must
depend on other organisms as a source of food (energy) and are
heterotrophs.
• Organisms can be either producers or consumers in
terms of energy flow through an ecosystem.
Producers:
These are autotrophs that can make organic molecules (glucose)
by the process of photosynthesis by using inorganic molecules
(carbon dioxide - CO2 and water - H2O).
Examples: Algae, grasses, trees, etc.
The Consumers:
They are the heterotrophes, that depend on other living organisms for food.
They cannot make their own food.
Primary Consumers:
Herbivores that each vegetation
Ex. : Grasshoppers, rabbits,
snails, etc.
Secondary Consumers:
Carnivores that eat the herbivores
Ex. : cats, foxes, owls, etc.
Tertiary Consumers:
Top carnivores (may eat other consumers)
Ex. : Lions, bears, wolves, etc.
The Decomposers:
They decompose (break down) dead organic material and return essential
nutrients to the soil which helps plants grow.
Ex. : Bacteria and mushrooms
Trophic level
• Refers to the organism’s position in the food chain
• Autotrophs are at the base (first trophic level).
• Organisms that eat autotrophs are called herbivores
or primary consumers (second trophic level).
• An organism that eats herbivores is a carnivore and a
secondary consumer. (third trophic level)
• A carnivore that eats a carnivore that eats a herbivore
is a tertiary consumer (forth trophic level).
• Omnivores eat both animals and plants.
Feeding Levels
Energy and Nutrient Flow Through the Ecosystem
The movement of energy is shown by the dark arrows.
The movement of the inorganic nutrients is shown by the open arrows.
Inorganic nutrients are cycled, energy is not.
ENERGY
• At each level of the food chain, about 90% of the energy is
lost in the form of heat.
• The total energy passed from one level to the next is only
about one-tenth of the energy received from the previous
organism.
• Therefore, as you move up the food chain, there is less
energy available.
• Animals located at the top of the food chain need a lot
more food to meet their energy needs.
Food Chains
• A food chain is the path of food from a given final
consumer back to a producer.
grass  grasshopper  mouse  snake  hawk
• The real world is more complicated than a simple food chain.
A more realistic depiction of who eats whom is called a food
web that depicts interlocking food chains.
Example of a food chain (out of order) and the associated
trophic (feeding) levels - complete
Organisms
Type
Trophic
Levels
Raven
Grasshopper
Ladybug
Grasses
Mushrooms
Bacteria
Example of a food chain (our of order) and the associated
trophic (feeding) levels
Organisms
Raven
Grasshopper
Ladybug
Grasses
Mushrooms
Bacteria
Type
Tertiary
Consumer
(top
carnivore)
Primary
Consumer
(herbivore)
Secondary
Consumer
(carnivores)
Producer
(plants)
Decomposer
Trophic
Levels
Fourth
Second
Third
First
Feed off all
levels
• http://www.youtube.com/watch?v=TE6wq
G4nb3M (ecology song)