(MAE) Energy Flow Lesson

Energy Flow Lesson

Glucose is a simple sugar that supplies energy to many organisms. Plants use the energy from the sun to produce glucose during photosynthesis. Grasshoppers obtain energy from glucose when they eat plants. A mouse obtains energy when it eats the grasshopper. Energy is transferred to the owl when it consumes the mouse. The sequence of events or feeding order in which an organism obtains energy within a community is called a food chain. It almost always begins with an organism that captures its energy from the sun.

 

Every organism has an energy role in the food chain. It is determined by how that organism obtains energy by interacting with other living organisms in its ecosystem. The three main energy roles are producer, consumer, and decomposer. Producers harness energy from the sun to make their own food. Every food chain begins with the producer. Plants are the primary type of producers but some bacteria, algae, and protists can also make their own food. Consumers are organisms that can't make their own food. They must feed on, eat, or consume other organisms. All animals are consumers. They can be classified based on what they consume or eat. The four types of consumers are herbivores, carnivores, omnivores, and scavengers.

 

See if you can match the consumer with the correct definition.

 

Unlike your pet hamster or goldfish, when a lion in an African jungle dies there is no one to bury its remains. The hamster, goldfish, and lion do have one thing in common. When they die, their remains are recycled into the ecosystem by decomposers. The organic matter in dead animals is broken down into simpler molecules that can become part of the soil. Decomposers feed on dead organisms so that the food chain is not broken but will continue to move energy through an ecosystem. Some common decomposers are bacteria and mushrooms.

Look at the food chain below. The arrows always point in the direction of energy flow.

In a food chain, the organism that eats the producer is known as the first-level consumer. The second-level consumer eats the first-level consumer. The third-level consumer eats the second-level consumer. This course of action takes place as the levels of the food chain increase.

 

Complete the following activity.

 

A food chain shows only one pathway of how energy can be transferred in an ecosystem. However, just like me and you, almost every animal's diet consists of a variety of organisms. Many consumers eat more than one type of food. For example, wolves are carnivores. They will eat animals as large as an elk or moose. Wolves will also eat mice, birds, fish, and even berries if necessary to prevent starvation. Grizzly bears eat elk, moose, fish and berries too. Thus, many organisms such as the elk and moose are part of more than one food chain. They can be eaten by grizzly bears or wolves. The overlapping food chains in an ecosystem make up a food web. It shows how many food chains are interconnected. Can you find the squirrel in the food web? It is a part of three food chains. Did you notice that the squirrel eats a variety of organisms which will help ensure it will have an adequate supply of food?

 

See description of diagram Links to an external site.

 

The diagram shaped like a triangle above is called an energy pyramid. Each level is known as a trophic level. The trophic levels get smaller as they move up the pyramid. An energy pyramid is a diagram that shows the amounts of energy that moves from one level to the next in a food web. The greatest amount of energy is at the bottom of the pyramid. The producers such as grass, trees, and shrubs are located at the bottom of the pyramid. Only about 10% of energy is transferred from one trophic level to the next. The other 90% is used by the organism to carry out its life processes or it is lost to the environment as heat. Imagine a sheep grazing on a farm. There is a lot more grass on the farm compared to sheep. Grass is at the bottom of the pyramid and it has the greatest amount of biomass. Since grass gets its energy from the sun, it also has the greatest amount of energy available. Energy is measured in kilocalories. Let's say there is 1,000 kcal of energy available in the grass. When the sheep eat the grass, they are going to store 10% of that energy in their bodies and use 90% of it. There will be about 100 kcal of energy stored in the sheep. If a second-level consumer such as a fox eats the sheep; it will gain 100 kcal of energy. The fox will use 90% of that energy it got from the sheep. The wolf will contain only 10 kcal of energy for the next predator. The biomass of all the organisms at each trophic level decreases as the amount of energy decreases up a food chain. There are more producers (grass) than first-level consumers (sheep). There are more first-level consumers than second-level consumers (foxes). Therefore the size of the population of organisms decreases at each higher level of the food chain.

The following video explains how matter and energy are organized in living systems in such a way that they help the organism adapt to its environment. The video is approximately 20 minutes long. Pause the video when necessary to make notes.

 

Organization in Living Systems Presentation

 

 

 

Prepare to take a tour of the food chain. Come along on an expedition with Dr. Brian Jerome to examine how energy and matter are transferred through the environment. We will learn about food chains and webs by studying the interactions of the various species of plants and animals. The video is approximately 17 minutes long. Pause the video when necessary to make notes.

 

Food Chains and Webs Presentation

 

 

[CC BY 4.0] UNLESS OTHERWISE NOTED | IMAGES: LICENSED AND USED ACCORDING TO TERMS OF SUBSCRIPTION