The Effect of Temperature on Yeast Respiration

The Effect of Temperature on Yeast Respiration

PLAN

Aim:

To determine the effect of temperature upon respiration of Yeast.

Prediction:

I predict that the respiratory rate of the yeast will increase in

speed as the temperature of the water increases. However, it may reach

a peak, and slowly decline as the temperature increases further.

My reason for the above prediction is that, anyone who has cooked,

knows that yeast is supposed to respond in warm water, so I believe

that the warmer the water, the more bubbles of CO² produced. Also, the

oxygen produced in the initial stages of the experiment will allow the

speed of reaction, of converting glucose to energy, to increase

additionally. It will decrease once all the material has reacted,

and/or because the temperature is too high for the yeast to respire as

the heat has denatured the yeast's enzymes and they can no longer fit

their substrate, and therefore decreasing their capability to work.

Method:

The yeast is put into a glucose solution, this is because the glucose

provides the energy for the yeast to respire.

We will take 7 readings of heated water (starting with 10°c), each

with a 10°c interval, and observe how many bubbles of CO² each

temperature allows the yeast, placed in the beaker of water, to

produce.

I chose to take 7 readings as 7 is an easy number to work with to

obtain and record sensible, clear results. A 10ºc interval allows us

to see a broad range of temperatures and therefore, a useful and

varied set of results.

Prior to this investigation, we carried out a shorter, irregular

experiment of the same kind which produced our preliminary results.

This helped as it gave me some indication of what the 'real'

experiment would prove and how much/little the variables needed

altering.

Precise and reliable evidence will be produced as the suggested method

is specific and easy to follow yet will produce a range of results;

accurate results will be obtained by repeating the experiment 3 times,