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Food chains and Food webs

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Presentation on theme: "Food chains and Food webs"— Presentation transcript:

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

2 What would happen if? The sun disappeared

3 What would happen if? There were no insects?

4 What would happen if? There were no rats or mice?

5 What would happen if? We could grow no plants

6 All living things need energy to survive
The flow of energy from organism to organism is called a FOOD CHAIN

7 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

8 Food chains and food webs

9 Producers consumers and decomposers
Different organisms have different roles in the food chain Producers Consumers Decomposers FOOD WEBS start with the sun Sun gives out light energy Plants uses energy to make their food

10 Producers Plants are called producers because they can make their own food All organisms are dependent on the oxygen that plants produce

11 Producers (continued)
Plants trap sunlight in their leaves and use chlorophyll to help them use sunlight to make carbohydrates. This is called photosynthesis:

12 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: Herbivores Carnivores Omnivores

13 Types of consumers Herbivores: eat only plants

14 Types of consumers Carnivores: eat only meat

15 Types of consumers Omnivores eat both plants and animals

16 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

17 Food Chain

18 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

19 Biomass pyramid If one organism is removed, another must replace it or it will upset the balance.

20 Your task Explain why all food webs start with the sun
In your workbook, answer questions 1 – 4 on page 237 of your textbook

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