1. 4-3-18 Modeling Energy Flow

2. Do Now: Take out your homework and answer the following questions in your science notebook
1 This type of consumer eats only producers.
A. carnivore
B. herbivore
C. detritivore
2. This type of consumer eats dead plant or animal material
A. omnivore
B. detritivore
C. herbivore
3. Which type of organism change the energy available in its environment into food energy it uses to live?
A. producers
B. carnivores
C. herbivores

3. HW Review: Key Concept Builder – How does energy move in ecosystems?
the Sun
changes light energy from the Sun into food energy
chemical processes that change the energy into food energy
changes chemical energy into food energy
Possible answers: plants, algae, some microorganisms
the Sun (also accept light energy)
bacteria near vents in the ocean floor
chemicals (also accept chemical energy)
Possible answer: animals
other organisms

4. HW Review: Key Concept Builder – How does energy move in ecosystems?
Possible answers: deer, cows
producers (also accept plants)
Possible answers: lion, sharks, snakes
other consumers (also accept animals)
Possible answers: humans, raccoons
producers and other consumers (also accept plants and animals)
Possible answers: fungi, worms, some bacteria
dead materials

5. How is the movement of energy in an ecosystem modeled?
Standard: SC.7.L.17.1
Lesson Objective: Students will be able to illustrate how to model energy movement in an ecosystem

6. Modeling Energy Flow
Food chains and food webs are models used to help understand how energy travels through a community.
food chain: a model that shows how energy flows in an ecosystem through feeding relationships.
Cadena alimentaria: modelo que explica como la energia fluye en un ecosistema a traves de relaciones alimentarias.
Note: arrows point in the direction that energy travels.
Food chains also show how the size of one population affects other populations. For example, if the amount of mice decrease, the snakes and grasshoppers might be affected.
Grasshoppers may increase as they have less predators.
Snakes may decrease as they have less prey.

7. Amount of available food energy decreases
Modeling Energy Flow
Each stage of a food chain has less available food energy than the last one because some food energy is converted to thermal energy (heat) and moves to the environment.
It takes a lot of plant material to feed one grasshopper, and then many grasshoppers to feed one mouse. A mouse uses some of that food energy and the rest is transferred into thermal energy.
Amount of available food energy decreases

8. Modeling Energy Flow
food web: a model of energy transfer that can show how the food chains in a community are interconnected.
Red alimentaria: modelo de transferencia de energia que explica como las cadenas alimentarias estan interconectadas en una comunidad.
Food webs show that food energy can move through several different pathways. For example, the energy in a mouse might be consumed by a fox or a hawk.
Food webs also show the amount of biodiversity in an ecosystem. Biodiversity contributes to the sustainability of organisms.
If there was a decrease in mice, the buzzard can still eat snakes or rabbits and may still survive.

9. Turn & Talk Compare a food chain with a food web.
A food web is a network of food chains that move energy throughout an ecosystem.

10. Modeling Energy Pyramids
Amount of available food energy decreases
Remember, as energy travels through different organisms, the amount of food energy decreases.
An energy pyramid is a model that shows the amount of food energy available in each link of a food chain.
Piramide energetica: modelo que explica la cantidad de energia disponible en cada vincula de una cadena alimentaria.
More food energy is available at the “base” of an energy pyramid, where producers are.
Each level is called a trophic level.

11. Modeling Energy Flow Tertiary consumers (usually carnivores)
Secondary consumers (usually carnivores)
Primary consumers (usually herbivores)
Producers

12. Video Summary: Amoeba Sisters – Food Webs and Energy
Homework: Complete Key Concept Builder worksheet – How is energy transfer modeled?
Video Summary: Amoeba Sisters – Food Webs and Energy

13. Mini-Lab: How is energy transferred in a food chain?
Purpose: to illustrate that only a fraction of the available energy is transferred at each trophic level in a food chain. 1. Each student is assigned a role. One student is the Sun. Others might be plants, mice, or an owl. The Sun will give one cup of dried beans (to represent energy) to each plant. 2. Each plant should keep 20 of its beans and put the rest into a box. This represents energy that the organism does not pass on. 3. Each mouse takes 20 beans (representing usable energy) from the plants in its group. Each mouse can use only 8 beans. Each mouse should keep 8 beans and put the rest into the box. 4. The owl should take 8 beans from each mouse. The owl uses only 1 bean and puts the rest of the beans into the box.
Pd. 1: 29 students (1 sun, 18 plants, 9 mice, 1 owl)