Anaerobic Respiration of Yeast

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Anaerobic Respiration of Yeast

Aim: To investigate the effect of temperature on anaerobic yeast


Basic outline plan: I plan to force a solution of yeast and glucose to

anaerobicly respire. I plan to measure the gas collected at allotted

intervals during a set period of time, when the solution is at

different temperatures. I will need equipment to accurately measure

the volume of gas collected, and an indicator to show me that all no

oxygen is present in my solution. I will also need to make a way to

force it to anaerobicly respire by creating an air tight layer over

the top of the substance.

Prediction & Background information:

I predict that a gas will be given off and this gas will be CO2 as we

are anaerobicly respiring yeast.

We know that Anaerobic Respiration In yeast has the following formula.

[IMAGE]Glucose Carbon Dioxide + Ethanol + Energy

[IMAGE]C6H12O6 2CO2 + 2C2H5OH + 210 KJ/Mole.

I predict that the volume of gas expelled will increase with

temperature. I believe this for a few reasons. The first is due to the

'Kinetic theory', this states that the extent of a molecules movement

depends on its state and temperature. As temperature increases, the

particles become more 'exited', and so move around and collide and

react more frequently and rapidly. It is these collisions which cause

the reaction. We also know that heat is a catalyst in all reactions.

I also know that yeast is an enzyme and all enzymes have an optimal

temperature at which they work best, this is around 45º for yeast.

However I predict that if the temperature is raised too much, then the

reaction will not occur at all. I believe this because yeast is an

enzyme, and according to the, 'GCSE revision guide' and the lock and

key theory, enzymes are protein molecules, and each enzyme has a

different shape for a certain reactant to fit into. This is called the

active sight. But protein molecules and the active sight become

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