Food chains and Food websObjective: To understand where energy comes from and how it flows from organism to organism.

What would happen if?

The sun disappeared

What would happen if?

There were no insects?

What would happen if?

There were no rats or mice?

What would happen if?

We could grow no plants

All living things need energy to survive

The flow of energy from organism to organism is called a FOOD CHAIN

A food chain is:

A simple relationship that shows energy flow from one organism to another

It is a flow chart

All food chains start with the sun

Plants get their energy from the sun to grow,

Animals get their energy by consuming plants

These relationships are actually quite complex, and they are shown in FOOD WEBS

Food chains and food webs

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Producers consumers and decomposers

Different organisms have different roles in the food chain1. Producers

2. Consumers

3. Decomposers

FOOD WEBS start with the sun Sun gives out light energy Plants uses energy to make their food

Producers

Plants are called producers because they can make their own food

All organisms are dependent on the oxygen that plants produce

Producers (continued)

Plants trap sunlight in their leaves and use chlorophyll to help them use sunlight to make carbohydrates.

This is called photosynthesis:

Consumers

Animals are called consumers because they are unable to make their own food and must eat plants or other animals

There are 3 types of consumers:1. Herbivores

2. Carnivores

3. Omnivores

Types of consumers

Herbivores: eat only plants

Types of consumers

Carnivores: eat only meat

Types of consumers

Omnivores eat both plants and animals

Decomposers:

Decomposers get the energy they need as they break down dead matter

If plants or animals die without being eaten, the body is broken down by bacteria and fungi

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Food Chain

Energy flow through a food web

Not all energy is passed on in the web

Some is lost as heat, or used by the organism that consumes for growth and movement

Energy is also lost in the cellular reactions each organism carries out to survive

As you move up the web, there is less energy to be passed on

This means fewer organisms at each level

Biomass pyramid

Your task

Explain why all food webs start with the sun

In your workbook, answer questions 1 – 4 on page 237 of your textbook