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 Energy from sunlight CO 2 absorbed from air O 2 released to air H 2 O absorbed from soil Photosynthesis Sugar synthesized Minerals absorbed from soil Growth

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 determines the population size of each trophic level More organisms at lower trophic levels

A Food Web Simple food web on a short-grass prairie Numbers represent trophic levels =producer 2=primary consumer 3=secondary consumer 4=tertiary consumer

Energy Transfer and LossHeat Heat Producer Primary Consumer Secondary Consumer Detritus Feeders Heat Chemicals

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 a Prairie 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