Ecosystems Food Webs

Energy exchange

Questions• Which of the following would represent a good

investigative experiment testing for affects of a drug on pregnancy?

• 1) A pregnant mouse given 1 ml of a drug and a non-pregnant mouse given 1 ml of a placebo.

• 2) A pregnant mouse given 1 ml of a drug and a non-pregnant mouse given 1 ml of a drug.

• 3) A pregnant mouse given 1 ml of a placebo and another pregnant mouse given 1 ml of a drug.

• 4) A non- pregnant mouse given 1 ml of a drug and a non-pregnant mouse given 1 ml of a placebo.

Ecosystems

• On a blue index card: Write down a definition of an ecosystem. Time limit is 2 minute.

• Pair-Share your definition and then on a green index card write a shared definition between you and your partner.

Ecosystems

• A community of organisms (i.e. plants and animals) living together with their environment (non-living aspects), functioning as a unit.

Energy Flow, Nutrient

Cycling, & Feeding

Relationships

•Nutrients (purple) neither enter nor leave cycle

•Energy (yellow) is not recycled

–Captured by producers

–Transferred through consumers (red)

–Each transfer loses energy (orange)

Primary Productivity: Photosynthesis

• Life uses < 0.03% of the sun's incident energy

• Most is lost as heat from respiration

EnergyEnergyfromfrom

sunlightsunlight

COCO22 absorbed absorbedfrom airfrom air

OO22 released released

to airto air

HH22OO absorbed absorbedfrom soilfrom soil

PhotosynthesisPhotosynthesisSugarSugarsynthesizedsynthesized

MineralsMineralsabsorbedabsorbedfrom soilfrom soil

GrowthGrowth

Colored index cards

• Use a purple index card. It has been said that all flesh is grass. Explain in a couple of sentences why that statement could be true.

Food Chains• (a) A simple terrestrial

food chain.

• (b) A simple marine food chain.

• 10% law determinesthe population sizeof each trophic level

• More organisms at lower trophic levels

A Food Web•Simple food web on a short-grass prairie

•Numbers represent trophic levels

11

1122

22

22

2222

22

2222

33

33

33

33

3333 44

44

44

1=producer2=primary

consumer3=secondary

consumer4=tertiary

consumer

Energy Transfer and LossHeatHeat

HeatHeat

ProducerProducer

PrimaryPrimaryConsumerConsumer

SecondarySecondaryConsumerConsumer

DetritusDetritusFeedersFeedersHeatHeatHeatHeat

ChemicalsChemicalsChemicalsChemicals

Energy transfer

• Only 10% of the total energy is used at each level

– In other words if a producer has 100 calories of useable energy then an herbivore has only 10 calories of useable energy and a carnivore only has 1 calorie

An Energy Pyramid for aPrairie Ecosystem: The 10% Law

Food web exercise• Grab a name tag• Wait for instructions• Producers = candy

– Dinoflagellates=tootsie rolls– Green algae=butter toffee– Diatoms=hard candy– Brown algae=butterscotches

• Consumers– Primary=Turquoise– Secondary=dark green– Tertiary=Fluorescent green

• Primary pickup as many candy as possible in 30 seconds• Secondary tag as many producers as possible• Tertiary tag as many secondary

Food web exercise• Goal: ?• 10 % rule• Modify for fourth graders?

Questions

Which of the following statements best describes the movements of energy through an ecosystem?– 1. Energy flow through

– 2. Energy cycles

– 3. Energy increases

– 4. Energy recycles

Questions

• The amount of life that can be supported by an ecosystem is determined by the

• 1) Efficiency of the consumers

• 2) Number of producers and their efficiency

• 3) Number of heterotrophs and their efficiency

• 4) Number of decomposers and their efficiency

Questions

• If a wolf eats a rodent that ate a smaller insect that ate a plant, the wolf would be a(n):

• 1) primary consumers

• 2) decomposers

• 3) producers

• 4) secondary consumers

• 5) tertiary consumers