Energy Flow

B4e

OBJECTIVESKey Objective• Explain the flow of energy in the environment

• Construct pyramids of numbers from given information and explain what they show (C/D)

• Construct pyramids of biomass from given information and explain what they show (C/D)

• Distinguish between pyramids of numbers and pyramids of biomass. (B/A)

• Explain how the efficiency of energy transfer explains the shape of pyramids of biomass. (B/A)

• Explain how the efficiency of energy transfer explains the limited length of food chains. (B/A)

• Calculate the efficiency of energy transfer. (A*)

• Look at the picture of the freshwater aquarium above and answer the following questions.

1. Using the organisms in the tank, draw as many food chains as you can. Remember that the direction of the arrows shows the flow of energy (from plants).

2. Combine your food chains to form a food web.3. Name two producers. 4. Name two consumers.

STARTER

Food chainsA food chain shows where the energy goes in a food chain (in other words, “what gets eaten by what”):

Cabbage

Rabbit Stoat Fox

The arrows indicate where the energy is going

Plants convert the sun’s energy into

food

ProducerHerbivore (primary

consumer)

Secondary

consumer

Top carnivore (tertiary

consumer)

Match these words…Tertiary

consumer

Herbivore

Top carnivore

Producer

Secondary

consumer

Consumer

Omnivore

Carnivore

Primary

consumer

Usually plants. Starts off a food

chain

Animals that only eat plants

An animal that eats producers

An animal that eats primary

consumers

An animal that eats secondary

consumers

A general word for “an eater”

Eats only animals

Not eaten by anything else

Eats both animals and plants

Pyramids of numberIn this food chain we can see that the number of organisms in each stage is less than in the previous stage:

Cabbage

Rabbit Stoat Fox

We can draw a “Pyramid of Numbers” to show this pattern:

Lots of cabbagesSome rabbitsA few stoats

One fox

“Funny looking” pyramidsConsider this food chain instead:

Tree Greenfly Ladybird

Bird

ONE treeMany greenflySome ladybirds

One bird

Pyramids of biomassIn this food chain we can see that the mass of organisms in each stage is less than in the previous stage:

Cabbage

Rabbit Stoat Fox

We can draw a “Pyramid of Biomass” to show this pattern:

Mass of cabbagesMass of rabbitsMass of stoatsMass of foxes

Energy flow in a food chainConsider the energy flow in this food chain:

Cabbage

Rabbit Stoat Fox

100% 10% 1% 0.1%

Clearly, not all of the ___’s energy that becomes stored in the _______ will end up in the fox. Only around ______ is passed on to the next stage in each food chain.Energy is lost at each stage because of a number of

reasons: 1) Each organism has to ____, keep warm etc2) Energy is lost through faeces (______)Words – 10%, move, sun, waste, cabbage

Your Task…

• Research the meaning of the terms biomass and biofuels.

• Then find out;– The different methods of transferring energy

from biomass– Biofuels (how they are manufactured & uses)– Pros (reasons for development) and cons