Biology 3 GCSE (Micro-organisms)

Notes about Yeast and respiration.

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  • Created by: Edi Akpan
  • Created on: 25-03-12 14:25


Anaerobic (Fermentation) 

Glucose --> Ethanol + Carbon Dioxide + Energy

Used to make Beer


Glucose + Oxygen --> Carbon Dioxide + Water + Energy

Used to make bread

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Yeast converts sugars to carbon dioxide and some ethanol.

The carbon dioxide is what makes the bread rise.

As the carbon dioxide expands, it gets trapped in the dough, making it lighter.

The dough is kneaded, trapping air which provides a source of oxygen for Aerobic respiration. 

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Conditions For Bread Making

Temperature - Enzymes like to work in warm conditions (about 35°C)

Glucose - needed for respiration

Aerobic Conditions - Maximises CO2 produced

pH - Doesn't really matter

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