Food Chains and Food Webs

•Producer•Consumer•Herbivore•Carnivore•Omnivore

•Predator•Prey•Habitat• Food Chain• Food Web

Design questions where each of the preceding key words is the answer.

You have 7 minutes.

Then swap with someone on our lab bench.

Food Chain / Food Web Revision

1. What do the arrows represent in a food chain?Flow of energy (food chains are sometimes called energy-transfer chains)

2. What is the difference between a food chain and a food web?Food chains show what eats what in a community; food webs show food chains for an entire ecosystem

3. Label the following food chain using all of your fancy vocabulary:

grass → gazelle → cheetah

Copy the following food chains into your books and then answer the questions on

the next slide

Hawk

Fox Owl Human

Chicken Mouse Chicken

Wheat Wheat Berries

1. Combine the three food chains to form a food web2. Name two producers and two herbivores3. Name a secondary consumer4. List two predator-prey relationships5. Explain how a fox is a well-adapted carnivore6. Imagine that a disease has killed off some of the

mice. What affect would this have on:a) the owls?b) the chickens?

Copy the following food web and answer the questions on the next slide

sea bird

crab

barnacle

starfish

dog whelk

limpetmussel

small algae

SEA SHORE FOOD WEB

1. How many primary consumers are there?2. How many secondary consumers are there?3. Draw a food chain with 5 links from the food web4. Suppose all the starfish died from pollution.

Explain what would happen to the number of:a) mussels?b) small algae?

5. A fishing village nearby captures most of the crabs from the food web. Explain what affect this would have on the numbers of barnacles.

Biology for You

Page 323Questions 1, 2, 3

Homework

Complete the worksheet for next lesson (Thursday)

Pyramids of Numbers

• Food chains and food webs can show the feeding relationships in a community.

• But they do NOT tell us how many living organisms are involved.

• Scientists often represent the numbers in a food chain using a pyramid of numbers

oak leaves (600) caterpillars (100)

shrews (10)

owl (1)

• The area of each box in a pyramid of numbers shows how many living things there are at each stage of a food chain.

• Always start with the producer at the bottom of your pyramid

• Draw a pyramid of numbers for this food chain

oak leaves

caterpillars

shrews

owl

But be careful...pyramids of numbers do NOT always have this ‘pyramid’ shape...

Draw a pyramid of numbers for this food chainoak tree

caterpillars

blackbirds

buzzard

caterpillars

blackbirds

buzzard

oak tree

rose bush greenfly

ladybirds

parasites

Draw a pyramid of numbers for this food chain

greenfly

ladybirds

parasites

rose bush

Quick Recap

Complete the GCSE Worksheet