No carbon dioxide was produced for Tubes 1, 2, and 5. Since no carbon dioxide was produced, cellular respiration did not occur. Tube 1 contained albumin (protein) while Tube 2 contained butter (lipid). For this experiment, yeast was used as the experimental subject. Since yeast does not require proteins nor lipids, these substrates were left untouched. Furthermore, proteins and lipids are not sugars that are needed for cellular respiration to occur. Meanwhile, Tube 5 is the negative control. It contained distilled water, which is neither a substrate nor a sugar, so it was expected that cellular respiration will not occur. Yeast cannot digest food in water, thus it was also left untouched. On the other hand, carbon dioxide was produced in Tubes 3 and 4. This means that cellular respiration occurred. Tube 3 contained glucose (monosaccharide) while Tube 4 contained sucrose (disaccharide). Glucose and sucrose are both simple sugars. Since yeast requires simple sugars, these substrates were used for its cellular respiration. Tube 3 with glucose is the positive control. Since it is directly used for cellular respiration, it was expected to have the highest volume of carbon dioxide produced and the highest rate of carbon dioxide production. But as seen from the data above, the result for Tube 4 with sucrose had a higher volume of carbon dioxide produced and a higher rate of carbon dioxide production than that of Tube 3 with glucose. This may be because of some experimental error like inaccurate measurements. If it were not for the experimental error, then theoretically, the simpler the sugar or substrate, the higher the rate of cellular respiration of yeast. Nevertheless, through this experiment, it can be concluded that the nature of substrate affects the cellular respiration of yeast. For sugars used as substrates, the rate of cellular respiration increases over time, and as the rate of carbon dioxide production increases, the volume of carbon dioxide produced also increases.
cellular respiration and carbon dioxide