Final answer:
Stirring the yeast suspension ensures the even distribution of cells and provides the necessary oxygen for optimal yeast growth and fermentation activity, which allows for consistent experimental results.
Step-by-step explanation:
Stirring the yeast suspension at the start of the experiment is important for several reasons. One primary suggestion could be that stirring helps to evenly distribute the yeast cells throughout the suspension, ensuring that each part of the suspension has a consistent concentration of cells. This uniform distribution is crucial for experimental consistency, particularly if the suspension will be used for further experimental procedures. Furthermore, stirring can also aid in aerating the suspension, providing oxygen that yeast cells require for optimal growth and activity, as oxygen is a key component in aerobic respiration, which yeast can carry out in oxygen-rich environments. Oxygen is vital for the yeast to produce energy efficiently, thus stirring may increase the metabolic rate of the yeast, leading to more active fermentation and production of desired byproducts such as ethanol and carbon dioxide.