Investigating Anaerobic Respiration in Yeast

Investigating anaerobic respiration in yeast Problem statement: what are the product of fermentation? Procedure : 1. Prepare 2 boiling boiling tube and label it boiling boiling tube tube A and B 2. boiling tube A is filled with 5 ml of yeast suspension and 15 ml of boiled glucose solution 3. boiling tube tube B is filled with with only 15 ml of boiled glucose glucose solution 4. A thin layer of paraffin paraffin oil is put on top of the contents of both  boiling tubes 5. boiling tubes tubes are corked corked with stoppers stoppers with delivery delivery tubes tubes 6. the end of each delivery delivery tube is placed placed into a test tube tube filled with 2 ml of lime water  7. the initial initial temperatures temperatures of the contents contents in both boiling tubes are recorded 8. the apparatus apparatus is is left aside aside for for one hour  hour  9. after one hour, hour, the final temperatures temperatures are recorded recorded and the change in lime water is noted 10. 10. the stopp topper erss are are rem removed oved and any any sm smell ell tha thatt is is rel relea ease sed d from the boiling tubes is noted 11. the resu results lts are are record recorded ed in the the table table

results Boiling tube

A

B

At the beginning of  At the end of the the experiment experiment

At the beginning of  At the end of the the experiment experiment

Temperature (C)

30

31

30

30

Lime water

clear

cloudy

clear

Clear  

Smell

Smell of ethanol is Smell of ethanol is Smell of ethanol is Smell of ethanol is not detected detected not detected not detected

Discussion 1. an aerobic aerobic condition condition occurs when when a glucose solution solution is boiled and  paraffin oil is added to cover the glucose solution. This prevent air from dissolving in the glucose solution. The glucose solution is boiled to remove dissolved oxygen 2. test tube tube B is set up as as a control control experim experiment ent 3. after one hour the contents contents of boiling tube tube A are cloudy and foamy whereas the contents of boiling tube B remain clear and non foamy 4. anaaerobic respiration respiration occur in boiling tube A because the lime lime water in test tube A turns cloudy, the temperature of the contents increases and the smell of ethanol is detected 5. the cloudy cloudy lime water indicates the presence presence of carbon carbon dioxide. dioxide. The increase in temperature indicates that heat energy is released. The semll of ethanol confirms that anaerobic respiration has taken place in boiling tube A. 6. the process that has taken place in in boiling tube A is fermentation. 7. Fermentation by yeast yeast produces ethanol, carbon carbon dioxide and energy energy conclusion in the absence of oxygen, yeast undergoes anaerobic respiration to produce

carbon dioxide, ethanol and energy. energy. The hypothesis is accepted