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…..