Energy Flow in EcosystemUNIT FIVE, LESSON 5.4BY MARGIELENE D. JUDAN

LESSON OUTLINEEnergy FlowEnergy-Flow Pyramids and Food PyramidsFood Chain and Food WebShort Quiz (10 items)

All organisms require energy,for growth, maintenance, reproduction, locomotion, etc.

Hence, for all organisms there must be:

1. A source of energy2. A loss of usable energy

Life on earth depends largely on the flow of energy coming from the sun.

34% solar radiant energy reaches the earth

Much of the energy is immediately reflected by the atmosphere, clouds and the Earth’s surface that

ONLY 1% REMAINS FOR THE ORGANISMS THAT LIVE ON EARTH.

Of this 1%, only 3% (0.03) or less is captured by the green plants and used in the process of photosynthesis

to produce compounds such as

carbohydrates, lipids (fats), and proteins.

Consumers obtain energy by eating and then oxidizing (using) all organic materialsDecomposers obtain energy by acting on organic waste materials/

ENERGY FLOWThe passage of energy from one organism to another

Energy Flow Diagram

Note that heat is always released, proving that not all energy are used..

Energy Flow Pyramids and Food Pyramids

Terminology of Trophic LevelsProducers - capture energy, produce complex organic compoundsPrimary consumers-feed on producers (herbivores)Secondary consumers-feed on primary consumers (carnivores)Tertiary consumers-feed on secondary consumers (carnivores)

The SUN is present at all trophic levels.

Note that only 10% of the original energy is left to feed the next level. This 10% is stored in the tissues of the organism in the form of ATP (adenosine triphosphate). The 90% is lost as heat.

kJ stands for kilojoule, a unit of energy

1000 kJ

100 kJ

10 kJ

1 kJ

10% loss of energy

producers

primary consumers

secondary consumers

tertiary consumers

heat heat

heat

An average human needs about 2000 calories per day.So if you want more energy next time, eat plants!Note: The more we go up a food chain/web/pyramid, the less energy becomes.

This is why we have so much plant life at the bottom of each food chain yet so few consumers at the top of each food chain. So the next time you take a car ride, you’ll know why there’s so many green plants and so few animals. It’s all about energy!

Food Chain and Food WebTogether, these groups (consumers, producers, etc.) make up a food chain.Food chains in both land and aquatic ecosystems always begin with the producers and are eaten by one or several consumers, and finally end with the decomposers. (producers > consumers > decomposers)

HerbivoreCarnivore Producer

100%

10%

1%

Problems

Too simplisticNo detritivoresChains too long

Food WebMore typically, food chains interact to form a food web.A food web is a combination of two or more food chains.

Plants have the most energy.

Several food chains also exist:Plant > rabbits > foxesPlant > squirrels > hawks and owlsPlant > herbivorous insects > predaceous insects > toads > snakesAnd many more…

Short Quiz tomorrow about this lesson.

Sources:Science Links 7https://www.csun.edu/science/scale/4th.../ppt/energy_ecosystem.ppthttp://shawmst.org/biology/chapter/how_do_living_things_get_energy/