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

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, Anaerobic

and aerobic. At first aerobic respiration will be present but only

until the oxygen that is already dissolved in the water. When the

oxygen is used up anaerobic respiration will be present which produces

the alcohol. The word equation for anaerobic respiration in yeast is:

Glucose Alcohol + Carbon Dioxide + Energy

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Anaerobic respiration is different in humans than it is in yeast

because we break down glucose into lactic acid whereas yeast breaks it

down into alcohol.

Input Variables

There are several different variables in this experiment such as:

The temperature of the water

Amount of Water

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Amount of Yeast

Amount of sugar

The time it is left for

In this experiment I will be changing the temperature of the water.

Prediction

==========

I predict that the hotter the water is the more carbon dioxide bubbles

will...

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reason why my test was accurate was that we used a thermometer to

check the temperature that is an accurate means of measuring heat. It

would have been even more accurate if we used an electronic

thermometer.

Improvements to Plan

====================

The only major improvement that I think would have been useful would

be to increase the temperature by only 5 C each time instead of 15 C.

This would help us to get a more accurate measurement of when the

yeast respires best. If I had more time I would have done this and

would have been able to find the optimum temperature for the yeast.

Another improvement would have been to measure the amount of carbon

dioxide given off instead of counting the bubbles. This would have

been a good improvement as bubble sizes change, they are never the

same size.