An Investigation to Show the Effects of Changing Temperature in Yeast Respiration

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An Investigation to Show the Effects of Changing Temperature in Yeast Respiration

Brief

Investigate one of the variables that effect respiration in yeast.

Background Knowledge ====================

Yeast is one of the various single celled fungi that form masses of miniature circular or oval cells by budding. When placed in sugar solution the cells multiply and convert the sugar solution into alcohol and carbon dioxide. Yeasts are used as fermenting agents in baking, brewing and the making of wine and spirits. Brewers yeast is a rich source of vitamin B.

Respiration in yeast is the production of the energy in the mitochondria of the cells. There are 2 types of respiration,
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If we heat the sugar solution too much then the enzyme will change shape and it will become impossible for it to join with the sugar to form a complex. This is called denaturing the enzyme, I predict that this will happen at 70 - 80 C.

Plan ====

First I will set up the apparatus as show above. I will add 1.5 grams of sugar to 25ml of water and dissolve it. When we have the water at the correct temperature I will add the same amount of yeast to the sugar solution. When the water is at the correct temperature I will let it stand for 5 minutes. The first test I am going to do will be at normal tap temperature (20 C). I am going to increase the temperature by 15 C each time until I get to 80 C. I will measure the amount of respiration by counting the carbon dioxide bubbles entering the second test tube.

Fair Test =========

To keep this investigation fair I am going to:

· Keep the amount of sugar and yeast the same throughout the investigation

· Keep the amount of water the same throughout the investigation

· Let the solution stand for the same amount of time each time, five minutes

· Add the yeast only when the sugar solution is at the correct temperature

Safety ======

This investigation isn't very dangerous; I will only have to be careful when handling the hot water.

Analysis ========

From my

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