IN: Where did you get your energy today? The ultimate source of energy on planet earth is the sun! Energy flows when organisms eat.

I. Trophic Structure and the Flow of Matter and Energy A.Trophic (Feeding )Levels = organisms that are the same number of steps from the sun a. Primary producers (autotrophs) Incorporate sunlight into chemical bonds of glucose by photosynthesis b. Primary, secondary & tertiary consumers Break chemical bonds of glucose to get energy by cellular respiration

B.Matter and Energy a. Flow in and out of ecosystems b. Are recycled within ecosystems c. Matter + Energy (IN) = Matter + Energy (OUT) Ecosystems Flow Cycle Conserved

Flow Cycle Conserve

C. Laws of Matter and Energy Apply to Trophic Structure a. Matter and energy can not be created or destroyed. b. C, H, O, and N are conserved (combine and recombine) to make new molecules as they move through ecosystems. c. There is a gradual loss of energy as it flows through ecosystems. d. Organisms use energy for growth, metabolism, and repair. Or, it is lost as heat to the environment. First Law Second Law

II. Ecological Pyramids = graphical representations (pictures) of trophic structure (feeding levels)

A. Three Types of Ecological Pyramids a. Numbers Pyramid = represents the total number of individuals per unit area Large numbers of producers form the base.

b. Biomass Pyramid = represents the amount of biomass (dry weight) of living organisms in a given area at a given time What are the units used for a biomass pyramid?

c. Productivity (Energy) Pyramid = represents the flow of energy through each trophic level at a fixed time What are the units used for an energy pyramid?

What do you notice about the numbers in each of the pyramids below ?

III. 10 % Rule a.Only about 10% of the energy entering a trophic level is transferred to the trophic level above. b.90% LOST at each level c. Energy pyramids have a step-like pattern because less energy enters each trophic level up the food chain. _4WORZB5ZcqIvhtZefDq7HHVxb1f92l8 DO DEMO 100% 10% 90% LOST

DEMO Materials: food coloring, 1000, 100, 10 ml graduated cylinders, one graduated 1ml transfer pipette Fill a 1000ml Flask with colored water. (Have student write 1000 ml on board) Pour 100 ml into 100 ml graduated cylinder. (Have student write 100 ml on board) Ask: What should I do with the rest of the water in the flask if it represents the energy available in the producers? (throw it away…..lost) Repeat for 100 ml and 10 ml cylinders (Have student write 10 ml and write 1 ml on board) Show off tiny 1 ml transfer pipette. Ask: What does 1ml volume represent? (the only energy left to the 3 rd level consumers) Ask: Where did all the lost energy go if this is a model of energy flow in a real ecosystem? ( growth, metabolism, repair, lost as heat to the environment) Ask: Why do fewer organisms occupy the higher trophic levels? (Inefficiency in energy transfer between each trophic level)

OUT: Grass Mouse Cat Coyote 10,000 calories Suppose 10,000 calories of energy are available at the level of the grasses. What is the total number of calories LOST by the time energy reaches the coyote? a. 90 calories b. 990 calories c calories d calories D.10,000 units in grass 1000 units in mouse (10,000 X.9 = 9000 lost; 1000 left) 100 units in cat (1000 X.9 = 900 lost; 100 left) 10 units left in coyote (100 X.9 = 90 lost; 10 left ) 10,000 – 10 = 9990 Easiest Way

Knowledge Targets Students know atoms of carbon, oxygen, hydrogen, and nitrogen are conserved (i.e., combined and recombined) to make new molecules as they move through the ecosystem. Students know energy flow, mass, and populations in ecology can be represented by pyramids. Students know only a fraction of matter consumed at lower trophic levels is transferred to higher trophic levels to produce growth and release energy through cellular respiration. Students know most energy is not transferred to higher trophic levels because it is used for growth, maintenance, repair, or lost as heat to the environment. Students know a small fraction of the energy from one trophic level is transferred to the next higher trophic level. Students know there are fewer organisms at the higher trophic levels of a food web. Performance Targets Students can apply the concept of conservation of matter and energy to food webs and trophic levels. Students can identify the relative proportion of organisms at each trophic level (i.e., lowest trophic level has the greatest biomass and stored energy). Students can use mathematical representations to account for the energy transferred through each trophic level within a food chain. Students can explain there are fewer organisms occupying the higher trophic levels due to inefficiency in energy transfer between each trophic level.