Final answer:
If yeast were placed in warm sugar water in a closed container, evidence of alcoholic fermentation, such as the production of ethanol and carbon dioxide gas, would be expected due to anaerobic cellular respiration.
Step-by-step explanation:
Evidence of Anaerobic Respiration in Yeast
If yeast were placed in a closed container with warm sugar water, one would expect to find evidence of anaerobic cellular respiration, specifically alcoholic fermentation. Yeast, being a single-celled eukaryotic organism, performs alcoholic fermentation in the absence of oxygen. The detectable evidence of this process would include the production of ethanol and carbon dioxide gas (CO2). These products result from the conversion of sugars such as glucose through the biochemical process of fermentation.
Lab Investigation and Results Interpretation
During a lab investigation designed to measure CO2 production, gas pressure sensors or other means could detect the increase in pressure as a result of CO2 being produced. Additionally, in a TSI slant test, which measures the fermentation of glucose, the appearance of a dark red color on the slant would indicate aerobic respiration, whereas acid production only in the butt suggests fermentation. Microbes such as yeast undergo fermentation when oxygen is not available for aerobic respiration.
The balanced chemical reaction representing the fermentation of glucose by yeast would be:
C6H12O6 → 2 C2H5OH + 2 CO2
This equation shows glucose (C6H12O6) being converted into ethanol (C2H5OH) and carbon dioxide (CO2), with the additional benefit of recycling NAD+ from NADH, allowing glycolysis to continue producing ATP in the absence of oxygen.