Ecosystems - Food Chains & Food Webs (KS3)

DO NOW TASK

What do you think the arrows represent in this image opposite?

UNDERSTANDING FOOD WEBS

LEARNING OBJECTIVES

- Describe how food webs are made up of a number of food chains.

- Make predictions about factors affecting plant and animal populations.

- Analyse and evaluate changes in a food web.

KEY WORDS

food chain

population

food web

producer

consumer

decomposer

trophic level

What is an Ecosystem?

"A community of interacting organisms + their physical environment."

examples; area of a desert or a lake or even your skin.

A Food Chain

• The organisms in a food chain are dependent on each other

• How would you list this food chain?

• Another could be "grass - grasshopper - frog - snake - hawk" (you MIGHT add "fungi" to be complete).

Food Chains + Food Webs

• Food Webs show all the Food Chains together within a specific ecosystem.

• Q1. Please name me a Producer from this Food Web

• Q2. Which Consumers feed on Fruit Flies?

• Q3. Please give me one complete food chain.

• Q4. What could be the impact if lots of Frogs died because of some illness?

Trophic Levels

• We can organise the organisms into Trophic Levels.

• The word Trophic is to do with food, eating, or nutrition.

• The organism on the level above EATS the organism on the level below.

Trophic Levels

• Level 1 is always a PRODUCER - an organism that gets its energy from the Sun via photosynthesis.

• All the other levels are CONSUMERS

• Not all the energy flows up to the next level because each CONSUMER has to "waste" energy to find a meal