Observing The Production Of Carbon (IV) Oxide By Anaerobic Respiration In Yeast.

Yeasts, which are tiny fungi, can brake down the pyruvic acid from glycolysis into ethyl alcohol (ethanol) and Carbon (IV) oXide in the absence of oxygen.
This process us called alcoholic fermentation.

In the following activity, you will investigate the production of Carbon (IV) oxide in anaerobic respiration in yeast.

Boil some water to expel all the dissolved oxygen and cool the water to room temperature.

Make up a 5% solution of glucose and a 10% suspension of dried yeast.

Place about five (5) centimeter cubed of the glucose solution and one(1) centimeter cubed of the yeast suspension in a test tube and cover it with a thin layer of liquid paraffin to exclude atmospheric oxygen from the mixture.

Fit a delivery tube as shown in the diagram below.

Dip the end of the open delivery tube into clear lime water.

With gently warming, observe the set up after ten (10) to fifteen (15) minutes and record your observations.

When the lime water turns milky, it indicates production of Carbon (IV) oxide from the fermentation (anaerobic respiration) of the yeast.

Experiment to show carbon production during anaerobic respiration (fermentation) in yeast.

Set up a controlled experiment in the same way but use a boiled yeast suspension which will not ferment.
The fact that the living yeast produces carbon dioxide despite being deprived of oxygen us evidence to support the contention that, anaerobic respiration is taking place.