14. 2 Energy Flow In Ecosystems

Essential Question:

How Do Living Things Affect One Another?

What are the Energy Roles in an Ecosystem?

How Does Energy Move Through an Ecosystem?

Energy Flow In Ecosystems

Pgs. 482-489

7th GradeMs. De Los Rios

Populations and Communities

Vocabulary

Producer – An organism that can make its own food

Consumer – An organism that obtains energy by feeding on other organisms

Herbivore – A consumer that obtains energy by eating only plants

Carnivore – A Consumer that obtains energy by eating only animals

Omnivore – A consumer that obtains energy by eating both plants and animals

Scavenger – A carnivore that feeds on the bodies of dead or decaying organisms.

Vocabulary

Decomposer – An organism that gets energy by breaking down wastes and dead organisms and returns raw materials to the soil and water

Food chain – A series of events in an ecosystem in which organisms transfer energy by eating and by being eaten

Food web – The pattern of overlapping feeding relationships or food chains among the various organisms in an ecosystem.

Energy pyramid – A diagram that shows the amount of energy that moves from one feeding level to another in a food web.

My Planet Diary pg. 482

I’ll Have the FishScientists have noticed something fishy going on with the wolves in British Columbia, Canada. During autumn, the wolves ignore their typical food of deer and moose and feast on salmon instead. Salmon are very nutritious and lack the big horns and hoofs that can injure or kill wolves. Plus, there are plenty of fish in a small area, making them easier to find and catch. Many animals depend upon the salmon’s annual mating trip upstream. Losing this important food source to overfishing would hurt the populations of bears, wolves, birds, and many other animals.

1.What are two reasons the wolves may eat fish in autumn instead of deer or moose?

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2. What effect could overfishing salmon

have on an ecosystem?

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What are the Energy Roles in an Ecosystem? Pg. 483

Just like an instrument has a role in a piece of music or a song, each organism has a role in the movement of energy through the environment. how it obtains energy

An organism’s energy role is determined: it interacts with other organisms

Each of the organisms in an ecosystem fills the energy role of : producer, consumer, or decomposer.

ProducersEnergy enters most ecosystems as sunlight.

An organism that can make its own food is a producer. Plants, algae, and some types of bacteria, capture the energy of sunlight

and store it as food energy. These organisms use the sun’s energy to turn water and carbon dioxide

into food molecules in a process called photosynthesis.

Producers are the source of all the food in an ecosystem.

Some producers make their own food without sunlight.Ex. Some bacteria can make their own food using the energy in hydrogen sulfide, a gas in their environment in rocks deep beneath the ground.

ConsumersConsumers Herbivores Carnivores Omnivores Scavengers

Organisms that obtain energy by feeding on other

organisms.

Consumers that eat only

plants

Consumers that eat only

animals

Consumers that eat both plants

and animals

Carnivores that feed on the

bodies of dead organisms

Fig. 1 Producers pg. 483

Producers are organisms that can make their own food.

Identify: Complete the shopping list below to identify the producers that are part of your diet.

WheatCornBanana

Decomposers

Decomposers break down wastes and dead organisms and return the raw materials to the ecosystem.

Mushrooms and bacteria are common decomposers.

What Happened Here? Fig. 2 pgs. 484-485

What Happened Here?While you were hiking, some hungry animals turned your

campsite upside down.

What Happened Here?

Can you determine the order in which the

organisms visited the campsite?

Assess Your Understanding pg. 485

1a. Describe: an organisms energy role is determined by how it obtains __________ and how it ____________with other organisms.

b. Explain: What is the main source of energy for all three energy roles? Why? __________________________________________________________________________________________________________________

I get it! Now

I know that the energy roles in an ecosystem are

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How Does Energy Move Through an Ecosystem pg. 486

Energy moves through an ecosystem when one organism

eats another.

A food chain is a series of events

in which one organism eats

another and obtains energy.

A food web consists of many

overlapping food chains in an

ecosystem.

Organisms may play more than one role in an ecosystem. Just as food chains overlap and connect, food

webs interconnect also.

Food Chains pg. 486

One way to show how energy moves in an ecosystem is with a food

chain. A food chain shows a series of events in which one organism eats another and obtains energy.

Food Webs Most consumers are a part of many food chains. Food webs are a more

realistic way to show the flow of energy through an ecosystem.

Food Webs are many overlapping food chains.

A food web consists of many interconnected food chains.1.Pick two organisms from the food web. Draw arrows connecting them to the decomposers. 2.How can the fox be both a second-level and third-level consumer?

Food Web

pg. 487

Energy Pyramids pg. 488

When an organism in an ecosystem eats, it obtains energy. The organism uses some of this energy to move, grow, reproduce, and carry out other life activities. These activities produce heat, a form of energy, which is then released into the environment. When heat is released, the amount of energy that is available to the next consumer is reduced.

A diagram called an energy pyramid shows the amount of energy that moves from one feeding level to another in a food web. The most energy is available at the producer level of the pyramid. As energy moves up the pyramid, each level has less energy available than the level below.

Energy Pyramids

.

Energy PyramidsSuppose that the producers at the baseof an energy pyramid contain 330,000 kilocalories. How much energy would beavailable at each level of the pyramid?

1.If mice ate all of the plants, how much energy would be available to them as first-level consumers?

2. If all of the mice were eaten by snakes, how much energy would the snakes receive?

3. If all of the snakes were eaten by the owl, how much energy would the owl receive?

4.About how much energy would the owl use for its life processes or lose as heat?

5. How much energy would be stored in the owl’s body?

Energy Pyramids

Assess Your Understanding pg. 489

2a. Define: A food (web / chain) is a series of events in which one organism eats another and obtains energy. A food (web / chain) consists of any overlapping food (webs / chains).

b. Compare and contrast: Why is a food web a more realistic way of portraying an ecosystem than a food chain?

c. Relate Cause and Effect: Why are there usually fewer organisms at the top of an energy pyramid?

Now I know that energy moves through an ecosystem when

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