Energy Flow and Food Webs

Ms. Petrauskas

The spheresHydrosphere: all of the earths water (as a solid, liquid

or gas)

Lithosphere: the earths solid outer layer (rocks, earth etc.)

Atmosphere: the layer of gases surrounding the earth

Biosphere: the zone around the earth where life can exist ( part of the lithosphere, hydrosphere and atmosphere)

Source of all energy…

Radiant energy- the energy radiated from the sun

Composed of ultraviolet rays and visible light70% absorbed by the hydrosphere and the

lithosphere and converted to thermal energyThermal energy warms the earthThe rest goes back to space

Solar Radiation Distribution

PhotosynthesisLight energy is used by some organisms and

is converted to chemical energy (plants, some algae and some protists)

Carbon dioxide + water sugar + oxygen

Carbon, Oxygen, and Hydrogen are rearranged via light energy into sugar and oxygen

Light Energy

Cellular Respiration The process by which sugar and oxygen are

converted to carbon dioxide and water to provide energy for the cell (Ex. Human cells use sugar to make energy)

Sugar +Oxygen carbon dioxide +water

EquilibriumA balance of photosynthesis and cellular

respiration are part of a stable and healthy ecosystem

Trophic levelsAutotroph –producer

Primary consumer – herbivore

Secondary consumer – usually carnivore or omnivore

Tertiary consumer- usually carnivore/ omnivore/ detrivore

Decomposer

A. Autotrophs (Producers)

Organisms that photosynthesize ( produce their own food)

Ex. Plants, algae and some bacteria

B. Heterotrophs (Consumers)

Organisms that must consume (eat) other organisms to obtain energy and building materials

4 types of consumers depending on what they eat. (Herbivores, Carnivores, Omnivores, Scavenger/ Detrivores)

1. Herbivore

Eat only plantsEx. Deer, giraffes, cows,

pandas, humming birds, grasshoppers

2.CarnivoresEat only animals (including insects)Ex. Killer whales, praying mantis, lions,

tigers, wolves, hawks

3.OmnivoreEat both plants and animalsEx. Bears, robins, raccoons, blue jays, fox,

humans

4. Scavengers/DetrivoresFeed on dead or decaying animal matterEx. Crows, crayfish, vultures –ScavengersEx. Worms, wood beetles

C. DecomposersAnother trophic levelConsume remaining dead or decaying

materialBreak down organic matter to its nutrientsNutrients are returned to the soilEx. Mould, yeast, mushrooms

Food chainA series of predator-prey relationships

(predators eat prey)Each chain begins with the sunProducers are next as they use the sun’s

energy to produce glucoseConsumers eat the producersDecomposers return nutrients to the soil

Create your Own food chainStart with the sun producer primary

consumer secondary consumer tertiary consumer end with the quanternary consumer or decomper

Arrows point in the direction of energy flow.

TRY IT!!!!!!

Food WebsA more accurate way to show feeding

relationships within a community

Consumers feed on many species, therefore reducing the vulnerability of any one prey species and reliability on one prey species

Useful to see what happens when one species is removed from the web or added to the web (invasive species)

Ecological PyramidsDisplay relationships between trophic levels.

As the pyramid narrows it shows that energy has been lost

Can represent energy, biomass or numbers of organisms

Energy lossAs one organism consumes another energy is

transferredSome energy is lost as thermal energy

Consider how much heat you lose compared to a plant!

Only 10% of the energy consumed by one trophic level is passed onto the next trophic level

10% is transferred between trophic levels

Carnivore (20J)

Herbivore (200J)

Plants(2000J of sun’s energy)

Create your own…..start with 1,000,000J of energy

100,oooJ

10,000J

1,000J

100 J

AnalogyCut a pie into 10 equal slicesOnly 1 piece is available to the next trophic

levelCut that slice into 10 smaller slicesOnly 1 of those is available to the next

trophic levelEnergy Available

Biomass Pyramid: mass of all living organisms in an areaPredato

r, parasite

sInsect herbivore

Grass

Normal