11.2 · Why Everything Depends on Producers

From Ohio 5th Grade Science Power Workbook · Chapter 11 · Lesson 11.2.

Big idea: Producers bring energy into the ecosystem, so every other organism depends on them.

Learning goals: Explain why producers are the foundation of a food web

Trace a consumer's energy back to a producer

Predict what happens if producers are lost

The energy has to come in somewhere

Consumers cannot make food. They have to eat.

Whatever a consumer eats was either a producer, or an animal that ate a producer. Trace any meal back far enough and you reach a plant.

That is why producers are the foundation of the food web.

Remove them and it stops

Take the producers out of an ecosystem and no new energy comes in.

The animals that ate plants run out of food first. Then the animals that ate those animals run out too.

Worked examples

Question: A fox eats a rabbit. The rabbit ate grass. Where did the energy in the fox's meal originally come from?

Steps: Start at the fox and work backwards. The fox got energy from the rabbit.

The rabbit got its energy from the grass.

The grass is a producer. It made its food using the sun's energy.

Answer: From the sun. The grass used sunlight to make food, the rabbit ate the grass, and the fox ate the rabbit.

Common mistakes

Meat eaters depend on plants too

A hawk never eats a plant, so it can look as though it does not need them.

It does. The hawk eats animals that ate plants. Take the plants away and the hawk's food supply disappears too, just one step later.

Check your thinking: Keep tracing backwards until you reach a producer. You always will.

Remember

Trace it back to a plant

For any animal, ask what it ate. Then ask what that ate. Keep going and you always arrive at a producer, and then at the sun.

Practice tip

Remember: 'Trace the energy' means go backwards.

Tip: When Ohio says trace the energy, start at the animal in the question and work backwards through what it ate. Keep going until you reach a producer and then the sun.