Respiration- an introduction for GCSE

by S J Freedman

Merchant Taylors’ School,

Crosby

What is respiration ?

• Breathing ?

• NO !

• Sweating ?

• NO !

What is respiration ?

• oxidising food

• releasing energy

• ...similar to burning

The main points

• Food (usually glucose, a sugar) “burns” using oxygen

• releasing useful energy

• producing carbon dioxide and water as waste products

In other words...

GLUCOSE

carbon dioxide & water

oxygen

ENERGY

Click to continue

Is that all there is to it ?

you should be so lucky...

There are two main stages...

carbon dioxide & water

oxygen

ENERGY

GLUCOSE

PYRUVIC ACID

AEROBIC

ANAEROBIC

energy

Click to continue

But...

Pyruvic acid is VERY poisonous !Pyruvic acid is VERY poisonous !Pyruvic acid is VERY poisonous !Pyruvic acid is VERY poisonous !

So it has to be destroyed!

PYRUVIC ACID

carbon dioxide & water

oxygen

ENERGY

GLUCOSE

AEROBIC

ANAEROBIC

energy

So it has to be destroyed!

GLUCOSE

ANAEROBIC

energy

And so, of course, it can’t be oxidised to release all that lovely energy!

What happens to it ?

• That depends what sort of organism you are

Plant Animal MicrobeClick on the picture to find out

or here to move on

Animals(in their muscles) make

LACTIC ACID

Ouch!

The lactic acid is a pain!

It’s what makes muscles hurt when they’ve been used a lot -

so much, in fact, that they can’t get oxygen fast enough and have to respire…

ANAEROBICALLY

Plants and microbesmake

CARBON DIOXIDEand

ETHANOL

Yeast

• Yeast is a FUNGUS.• It respires

anaerobically• to make carbon

dioxide.

• and ETHANOL

Some useful links

• Introduction

• Aerobic respiration

• Anaerobic respiration

• Fermentation – anaerobic respiration in microbes.

Return to start Finish