Lesson 4 continued

Energy Flow in

Ecosystems

Energy• Energy is needed for all life

processes, such as breathing, moving, growing, etc.

• The ultimate source of energy for almost every living thing is the sun.

2 key components•Producers•Consumers

What is a producer?

What is a consumer?

The Movement of Energy

• Living things do not create energy.

• Energy is just passed from one organism to another.

• It is released from food through the process of cellular respiration.

From the Sun to Producers

• Plants (producers) use the sun’s energy to make food (photosynthesis).

• They use most (~90%) of the energy stored in their food to grow, reproduce, etc.

• The food that is not used by the plant (~10%) is stored in the plant to be used later.

From Producers to Primary Consumers

• When primary consumers eat plants, they receive the energy that was stored in the plant.

• They use this energy (~90%) to move, grow and for all of the other processes necessary to stay alive.

• The energy that is not used up (~10%) is stored in their bodies.

From Primary Consumers to Secondary Consumers

• When secondary consumers eat primary consumers, they receive the energy that was stored in those organisms.

• They use this energy (~90%) to move and grow and for all of the other processes necessary to stay alive.

• The energy that is not used (~10%) up is stored in their bodies.

…and so on.• This energy is eventually

passed on to tertiary consumers, when the tertiary consumers eat them.

Energy Pyramid• An energy pyramid is a diagram

that shows the amount of energy that flows through an ecosystem.

HowStuffWorks Videos "Assignment Discovery: Energy Flow"

Energy Pyramid• The shape of the energy

pyramid represents two things: – the decrease in the amount of

energy moving from producers to primary consumers to secondary consumers to tertiary consumers

– the decrease in the number of organisms in an ecosystem as you move up the food chain.

Energy Pyramid

Questions

1. Why would there be less energy available to move from one level to the next?

2. Why would an ecosystem have fewer organisms as you move up the food chain?

Answers

1. The reason there is less energy available from one level to the next is because some of the energy was used up by the organisms in the previous level to carry out life processes. Not all of the energy was stored in their bodies. In fact, only about 10% of the energy taken in at a level is passed on to the next level, while 90% is used up.

Answers

2. If there is less energy passed on to each level, then there is not enough energy to support a lot of organisms.