2 Wednesday, April 12, 2017Food Chains & Food WebsTo understand food chains and food webs, and the transfer of energy within these
3 E.g. rabbit fox means the rabbit is eaten by the fox Food ChainsWhat is a food chain?A food chain shows what is eaten by what – each arrow means ‘eaten by’E.g. rabbit fox means the rabbit is eaten by the fox
4 Food ChainsWhat is the food chain in the following habitat: -
5 Food ChainsThis food chain shows a leaf is eaten by a caterpillar, which is eaten by a bird, which is eaten by a catProducer1° Consumer(Herbivore)2° Consumer(Carnivore)3° Consumer(Carnivore)Why do the organisms eat one another?Energy is transferred from one organism to another, in the direction of the arrow
6 EnergyFood chains are never very long (usually only 4/5 stages at most) – why is this?Remember the arrow shows the energy being transferred from one organism to the next - between each step energy is lost in a variety of ways, including: -Growth of the organismReproductive costsLost through waste products (poo)Lost through heatThis is why food chains are never that long - as lots of energy is lost from one stage to the next
7 Food ChainsYour task is to make 3 food chains consisting of at least 3/4 organisms in each – e.g. leaf caterpillar bird catFor each food chain draw out your animals, adding the key words: producer, consumer (1°; 2°; 3°) and if you can: herbivore, carnivore or omnivoreOnce you have done this complete a food chain for your favourite celebrity / sports person / musician / actor etc… with a paragraph underneath explaining how they live based on this food chain
8 Food WebsIn most habitats organisms normally eat / are eaten by more than one other organismTo represent this we use food webs (like food chains but they interlink with one another), e.g. a pondHere the producers are the pondweed and the microscopic algaeMayfly nymphs eat the pondweed and microscopic algae, and freshwater shrimp eat the microscopic algaeDragonfly nymphs and brown trout eat the mayfly nymphs and freshwater shrimpBrown trout also eat the dragonfly nymph!
10 Food WebsYou have 5 minutes to have an answer to every question (you do not need to write your answers down): -Name the producerName 2 herbivoresName 2 top carnivoresHow many 2° consumers are there?Which food chains include a moth larvaPlantsVole; moth larva; aphidStoat; owl5 - stoat; spider; ladybird; blue tit; owlBlue and orange food chain
11 Key termsProducer - utilise the sun’s energy to produce their own food, e.g. plants and algaeConsumer - organisms that require eating other organisms for their energy supply. These can be primary consumers which eat the producers; secondary consumers which eat the primary consumers; or tertiary consumers which eat the secondary consumers etc…Carnivore - an organism that eats other consumers, e.g. lionHerbivore - an organism that eats other producers (plants), e.g. cowOmnivore - an organism that eats both producers and consumers, e.g. human
12 Carnivore, Herbivore Or Omnivore? Are the following carnivores, herbivores or omnivores?
13 Carnivore, Herbivore Or Omnivore? Are the following carnivores, herbivores or omnivores?HerbivoreCarnivoreHerbivoreOmnivoreCarnivoreOmnivoreCarnivoreOmnivoreHerbivore
14 Food ExamplesComplete the food chains and food webs worksheet
16 BalancePopulations in a food chain are dependent upon one another – there is a balance between the producers and consumers in the food chainFor example if there are lots of giraffes they will eat a large quantity of the trees and shrubs until there may be insufficient amounts to support them. If this is the case many will begin to starve and die.Fewer giraffes means less food for lions, which will eventually see a population decrease.Less giraffes will allow more shrubs and tress to survive, so the giraffe population recovers, leading to the lion population recovering, until the process repeats itself…