Concept:Living organisms differ in their ability to respire with or without oxygen.
Explanation:Mould is an aerobic organism that requires oxygen for respiration.
In a low-oxygen environment, mould cannot respire adequately, so it dies after a few days.
Yeast cells, however, can switch to anaerobic respiration in the absence of oxygen.
This anaerobic respiration is known as fermentation.
During fermentation, glucose is broken down without oxygen to release energy.
The simplified equation for fermentation is:
C6H12O6→2C2H5OH+2CO2Because yeast can respire anaerobically, it still produces energy and survives in the low-oxygen environment.
Thus, the observation shows that respiration can occur in yeast even when oxygen is absent, but mould cannot do the same.
Answer:C. Respiration can take place in yeast cells in the absence of oxygen