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Energy in Ecosystems
ALL LIVING THINGS USE ENERGY
The earth is SOLAR POWERED!
The source of all energy for ecosystems is the Sun.
The Sun:
1) lights and warms the surface of the Earth
2) provides energy needed to evaporate water from the oceans and lakes, to form rain and snow
3) provides energy used by green plants to make the compounds that maintain their lives and serve as food for all organisms
Of the energy that penetrates into the lower atmosphere, about 30% is reflected by clouds or the Earth’s surface.
The remaining 70% warms the surface of the planet, causing water to evaporate, and generating the water cycle and weather.
Only a very small portion (about 1%) of the sun’s energy is actually used by green plants for PHOTOSYNTHESIS.
Photosynthesis
process by which green plants use sunlight to produce carbohydrates (glucose/sugars)
trap light energy into chemical bonds of sugar
AUTOTROPHS = PRODUCERS- make their own food- main producers on land are green plants and in water they are algae
About 1% of sunlight is absorbed by primary producers
Photosynthesis (1:59 min): http://www.youtube.com/watch?v=LgYPeeABoUs&feature=related
Another song (1:52 min): http://www.youtube.com/watch?v=C1_uez5WX1o&feature=related
Photosynthesis
6CO2 + 6H2O + light energy C6H12O6
+ 6O2
carbon dioxide gas + water + sunlight glucose + oxygen gas
Cellular Respiration
process plants use to obtain energy from glucose
C6H12O6 + 6O2 6CO2 + 6H2O + energy
glucose + oxygen gas carbon dioxide gas + water + energy
Adv. Cell Resp. song (4:54 min): http://www.youtube.com/watch?v=3aZrkdzrd04&feature=related
Adv. Glucose song (2:45 min): http://www.youtube.com/watch?v=jJvAL-iiLnQ&feature=fvw
Cellular Respiration Plants use the energy released for all the
processes inside their cells as well as for growth, repair of tissues and reproduction.
Animals also carry out cellular respiration to release the energy but must obtain glucose by eating food containing carbohydrates.
- Energy is used for movement, digestion, growth, repair and reproduction.
Energy Movement in Ecosystems
By categorizing living things by their trophic (feeding) level in their ecosystem, we can better understand how energy flows
Energy flows through an ecosystem in a series of steps in which organisms transfer energy by being eaten
What happens to all the energy in organisms at each level?
90% of the energy is lost at each transfer, most of it as heat
Only 10% of the energy that the animal eats is able to be passed on to an animal that eats it
We can take a look at this transfer through:
Food chains- simple model that shows how matter and energy move through an ecosystem
Food webs- shows all possible feeding relationships in a community at each trophic level
- Represents a network of interconnected food chains
Food chains and Energy Song (2:46 min): http://www.youtube.com/watch?v=TE6wqG4nb3M
Calorie definition - a unit of heat equal to the amount of heat required to raise the temperature of one kilogram of water by one degree at one atmosphere pressure; used by nutritionists to characterize the energy-producing potential in food
Food chain Food web(just 1 path of energy) (all possible energy
paths)
Definitions
AUTOTROPHS = PRODUCERS
- make own food using photosynthesis
HETEROTROPHS = CONSUMERS
- get energy from consuming other organisms
Other Heterotrophs/Consumers:
HERBIVORES – eat only plants
CARNIVORES – eat only animals
OMNIVORES – eat both plants
and animals
Other Heterotrophs/Consumers
DETRITIVORES – feed on plant and animal remainsExamples: mites, earthworms, snails, crabs, vultures
DECOMPOSERS – break down and absorb organic matterExamples: bacteria and fungi
4th trophic level
3rd trophic level
2nd trophic level
1st trophic level
Energy/Trophic Levels
First Trophic level – producers/autotrophs
Second Trophic level – primary consumers, herbivores that feed directly on producers
Third Trophic level – secondary consumers, primary carnivore that relies directly on primary consumers
Fourth Trophic level – tertiary consumers, secondary carnivore that relies directly secondary consumers
Keeps going…..