To understand anaerobic respiration in our school laboratory, I will demonstrate that CO2 is released during anaerobic respiration.
The following apparatus to be set accordingly:
Thermos flask, split corks, thermometer, wash bottle, glass tubes, liquid paraffin, glucose solution, yeast cells, bicarbonate solution.
1. Glucose solution after heating is poured into a thermos flask.
2. The thermos flask containing glucose solution is heated for a minute to remove dissolved oxygen from glucose solution and then kept to cool �t without shaking.
3. Some yeast is added to the glucose solution and fixes two-holed rubber stopper to the flask.
4. Oxygen supply from the air is cut off by pouring a layer of liquid paraffin on the mixture (Thermos is heat resistant can’t be used for boiling).
5. Insert one end of the thermometer into the thermos flask. See the end of thermometer kept in the solution.
6. Gas released is collected in a tube containing bicarbonate solution or lime water as shown in apparatus setup. Keep the apparatus undisturbed for one or 2 days.
1. After two days it is observed that lime water turns into milky white precipitate.
2. Increase in temperature noted on yeast cells respire and release energy.
3. The smell of alcohol comes from the flask.
These observations indicate that yeast cells respire anaerobically and release carbon dioxide.
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