Energy Flow in Ecosystems

Energy Flow in Ecosystems

Middle School

​

Learning Objectives

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

• Model how energy flows through an ecosystem using food chains and food webs.

• Explain how energy is transferred and lost between different levels in a food chain.

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

Key Vocabulary

​

Producer

An organism that makes its own food, often using energy from the sun.

​

Consumer

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

​

Decomposer

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

​

Food Chain

A series in which one organism eats another to obtain energy and valuable nutrients.

​

Food Web

A food web is a more realistic model of overlapping food chains.

​

Energy Pyramid

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

Energy Roles in an Ecosystem

​

Producers

• ​Producers like plants have the unique ability to make their own food.

• ​​They make food by using sunlight for energy in a process called photosynthesis.

• ​They form the foundation of the ecosystem’s energy and support other organisms.

​

Consumers

• ​Consumers get their energy by eating other living things for their food.

• ​​Herbivores eat plants, while carnivores get their energy from other animals.

• ​Omnivores are a type of consumer that eats both plants and animals.

​

Decomposers

• ​Decomposers, like bacteria and fungi, play a very important recycling role.

• ​​They get their energy by breaking down dead organisms and animal waste.

• ​This process returns important nutrients to the soil for producers to use.

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.

​

​

Types of Consumers

• A herbivore is a consumer that gets energy by eating only plants.

• A carnivore is a consumer that gets energy by eating other animals.

• An omnivore is a consumer that eats both plants and animals for energy.

• A scavenger is a carnivore that eats the bodies of dead organisms.

Multiple Choice

An organism that eats both plants and animals to get energy is called a(n)...

• Omnivore

• Herbivore

• Carnivore

• Scavenger

​

​

Food Chains and Food Webs

• A food chain is the simplest model for showing energy flow.

• ​It shows a single path where arrows point to the organism that eats.

• A food web is a more realistic model of overlapping food chains.

• It shows organisms have multiple food sources, creating an interconnected web.

Multiple Choice

How does a food web differ from a food chain?

• 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 energy flowing from the eater to the eaten.

​

​

What Is an Energy Pyramid?

• An energy pyramid shows how energy moves through different feeding levels.

• Producers are at the base and have the most available energy.

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

• The other 90% is used by organisms or lost as heat.

Multiple Choice

Approximately what percentage of energy is transferred from one feeding level to the next in an energy pyramid?

• 10%

• 50%

• 90%

• 100%

​

​

What Is Bioremediation?

• Bioremediation uses living organisms like bacteria and fungi to clean up contaminants.

• It is a natural way of reducing pollution in the environment.

• For oil spills, chemicals first break oil into smaller droplets.

• Then, decomposers like bacteria break down and remove the oil.

Multiple Choice

What is the primary goal of bioremediation?

• To use living organisms to remove environmental contaminants.

• To add chemicals that neutralize all pollutants instantly.

• To physically block oil from reaching shorelines.

• To create new habitats for marine animals.

​

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 show the flow of energy and nutrients.
Decomposers destroy nutrients forever.	Decomposers recycle nutrients back into the environment.

Multiple Choice

A vulture eats the remains of a dead antelope. How would you classify the vulture in the ecosystem?

• A scavenger, which is a type of carnivore.

• A producer, because it provides energy to decomposers.

• A herbivore, because it is part of the food chain.

• A decomposer, because it breaks down a dead organism.

Multiple Choice

If producers in an ecosystem have 10,000 units of energy, why do the consumers at the top of the energy pyramid have significantly less energy available to them?

• Because most energy is lost as heat at each feeding level.

• Because top consumers do not require as much energy.

• Because energy is destroyed by the producers.

• Because decomposers use up most of the energy.

Multiple Choice

What is the most likely long-term outcome for an ecosystem if all decomposers were suddenly removed?

• The soil would become poor in nutrients, leading to a decline in producers.

• Consumers would have an unlimited supply of food.

• The amount of energy in the ecosystem would increase.

• Producers would start getting energy from consumers instead of the sun.

Multiple Choice

A new housing development removes a large forest, destroying the main food source for a population of herbivores. What is the most likely cascading effect on the food web?

• The populations of carnivores that feed on the herbivores will decrease due to lack of food.

• The producers in the area will grow uncontrollably.

• The decomposers will have nothing to break down.

• The energy in the ecosystem will be recycled more quickly.

​

Summary

• Producers, consumers, and decomposers have vital roles in the flow of energy.

• Food chains, webs, and pyramids model how energy moves through an ecosystem.

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

• Human activities can disrupt food webs, but bioremediation can help clean up damage.

Poll

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

• 1

• 2

• 3

• 4