Food Webs

1. Food Webs IGCSE Biology

2. grass fox STARTER: Changes in food chain populations The organisms in a food chain are dependenton each other. Changes in the number of organisms in one part of the food chain can have dramatic effects on the rest of the food chain. rabbit What would happen to the number of rabbits and foxes if all the grass died out? • Rabbit numbers would decrease because they would have less to eat and may starve or stop reproducing. • Fox numbers would also fall as there would not be as many rabbits to eat.

3. plants aphid ladybird blue tit owl plants moth blue tit owl plants vole stoat plants vole owl What is a food web? Why is it a good idea for an organism to have different sources of food? Animals usually eat many different things and are involved in lots of different food chains: These food chains can be put together in a food web, which shows how the food chains are connected. What would the food web for these food chains look like? LETS ACT IT OUT!!

4. bluetit owl moth ladybird vole spider aphid plant Food webs chiffchaff stoat

5. TrophicLevel: the position anorganismhold in a foodchainFood web: a network of manyfoodchains

6. Reminder of keyvocabulary! • Primary producers (organisms that make their own food from sunlight are the base of every food chain • Primary consumers are animals that eat primary producers; they are also called herbivores • Secondary consumers eat primary consumers. They are carnivores and omnivores • Tertiary consumers eat secondary consumers. • Quaternary consumers eat tertiary consumers. • Food chains "end" with top predators, animals that have little or no natural enemies. • When any organism dies, it is eventually eaten by detrivores (like vultures, worms and crabs) and broken down by decomposers (mostly bacteria and fungi), and the exchange of energy continues.