Energy Flow in Ecosystems

Energy Flow in Ecosystems

Middle School

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Learning Objectives

• Describe the energy roles of producers, consumers, and decomposers in an ecosystem.

• Model the flow of energy through an ecosystem using food chains and webs.

• Explain how energy is transferred and lost between different feeding levels.

• Analyze how human activities can impact the flow of energy in an ecosystem.

Key Vocabulary

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Producer

An organism that can make its own food, often using sunlight, is called a producer.

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Consumer

An organism that obtains energy and nutrients by feeding on other living organisms in an ecosystem.

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Decomposer

An organism that breaks down biotic wastes and dead organisms, returning raw materials to the ecosystem.

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Food Chain

A series of events in which one organism eats another and obtains energy and valuable nutrients.

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Food Web

A model consisting of many overlapping food chains that shows how energy cycles through an ecosystem.

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Energy Pyramid

A diagram that shows the amount of energy that moves from one feeding level to another.

Key Vocabulary

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Carnivore

A type of consumer that gets its energy and all of its nutrients by eating animals.

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Herbivore

A type of consumer that obtains its energy and all of its nutrients from eating plants.

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Omnivore

A type of consumer that obtains its energy by eating a diet of both plants and animals.

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Scavenger

A specific type of carnivore that gets its energy by feeding on the bodies of dead organisms.

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Bioremediation

This process uses natural living things like bacteria and fungi to reduce contaminants in an environment.

Energy Roles in an Ecosystem

• Producers, like plants, make their own food using sunlight.

• Consumers get energy by eating other living things.

• Decomposers recycle nutrients by breaking down dead organisms.

Multiple Choice

What is a producer in an ecosystem?

• An organism that makes its own food.

• An organism that eats other living things.

• An organism that breaks down dead things.

• An organism that recycles sunlight.

Multiple Choice

What is the key difference between how consumers and decomposers obtain energy?

• Consumers eat living organisms, while decomposers break down dead organisms.

• Consumers get energy from sunlight, while decomposers get energy from water.

• Consumers make their own food, while decomposers eat living organisms.

• Consumers recycle nutrients, while decomposers make their own food.

Multiple Choice

What would be the most likely impact on an ecosystem if all decomposers were removed?

• The recycling of nutrients in the soil would stop.

• Producers would no longer be able to make their own food.

• Consumers would have an unlimited food supply.

• The ecosystem would have too much sunlight.

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Modeling Energy Flow: Food Chains & Webs

Food Chain

• A food chain is the simplest way to model the flow of energy.

• It shows a single path where one organism eats another to obtain energy.

• Arrows point in the direction that energy flows, from the eaten to the eater.

Food Web

• A food web is a more realistic model that shows many overlapping food chains.

• It shows how organisms can have multiple food sources in their environment.

• Human actions can disrupt food webs, affecting the entire ecosystem’s health and balance.

Multiple Choice

What is the primary purpose of a food chain model?

• To show how energy flows from one organism to another in an ecosystem.

• To list all the different types of plants in a habitat.

• To describe how organisms reproduce and raise their young.

• To explain how animals build their shelters.

Multiple Choice

How does a food web differ from a food chain in representing energy flow?

• A food chain shows a single path of energy, while a food web shows many interconnected paths.

• A food web shows a single path of energy, while a food chain shows many interconnected paths.

• A food chain only includes producers, while a food web only includes consumers.

• A food web shows how energy flows from the eater to the eaten.

Multiple Choice

Based on the structure of a food web, what can be predicted about the effect of a significant, human-caused decrease in one organism's population?

• The disruption can affect the health and balance of the entire ecosystem.

• The food web will immediately convert into a simple food chain.

• Only the organisms that are directly connected will be impacted.

• The energy in the ecosystem will increase to compensate for the loss.

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The Energy Pyramid

• An energy pyramid shows how energy moves between feeding levels.

• Producers form the base and have the most available energy.

• Only about 10% of energy transfers from one level to the next.

• Most energy is used for life activities and lost as heat.

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Multiple Choice

What is the main purpose of an energy pyramid?

• To show how energy moves between feeding levels.

• To count the number of species in an ecosystem.

• To illustrate how organisms grow over time.

• To map the physical locations of producers.

Multiple Choice

Why does only about 10% of energy transfer from one feeding level to the next?

• The energy is destroyed by the producers.

• Organisms at the next level do not need much energy.

• Most of the energy is used for life activities and lost as heat.

• The energy is saved by the organism for later use.

Multiple Choice

If a disease reduced the amount of energy transferred between levels from 10% to 5%, what would be the most likely outcome for the ecosystem?

• The producers would have less available energy.

• The energy available to top consumers would be significantly reduced.

• The total amount of energy in the pyramid would increase.

• Organisms would stop using energy for life activities.

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What Is Bioremediation?

• Bioremediation uses living things like decomposers to clean up environmental contaminants.

• An example is the Deepwater Horizon oil spill in the Gulf of Mexico.

• Chemicals were used to break the large oil patches into smaller droplets.

• Bacteria and fungi then broke down the oil, removing it from the water.

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Multiple Choice

What is the primary goal of bioremediation?

• To use living organisms to remove environmental contaminants.

• To physically block oil from reaching shorelines.

• To create new habitats for marine animals.

• To add chemicals that neutralize all pollutants instantly.

Multiple Choice

In the Deepwater Horizon oil spill example, what was the specific function of the bacteria and fungi?

• They acted as decomposers that broke down the oil.

• They were used to absorb the chemicals.

• They grouped the small oil droplets back into large patches.

• They consumed the fish that were harmed by the spill.

Multiple Choice

What is the most likely reason that chemicals were first used on the oil spill before the bacteria and fungi did their work?

• The cleanup would be less effective because the bacteria and fungi would have less surface area to break down the oil.

• The cleanup would be faster because the chemicals would not get in the way of the decomposers.

• The oil would have floated instead of forming droplets.

• The bacteria and fungi would have been unable to survive in the water.

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Common Misconceptions

Misconception	Correction
Energy is created in an ecosystem.	Energy flows from the sun and is transferred between organisms.
Food webs show which animals are bigger.	Food webs illustrate the flow of energy and nutrients between organisms.
Decomposers destroy nutrients forever.	Decomposers recycle nutrients back into the soil and water for producers.

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Summary

• Producers, consumers, and decomposers each have a role in the flow of energy.

• Food chains and food webs model how energy moves between different organisms.

• Energy pyramids show that only about 10% of energy moves to the next level.

• Decomposers are essential for recycling nutrients back into the ecosystem for producers.

• Human activities can disrupt the natural flow of energy in food webs.

• Bioremediation uses decomposers to clean up environmental damage like oil spills.

Poll

On a scale of 1-4, how confident are you about explaining how energy flows through an ecosystem?

• 1

• 2

• 3

• 4