Final answer:
Placing yeast into boiling water would kill the yeast cells by denaturing their enzymes, which would halt respiration and fermentation processes, leading to a rate of respiration that is effectively zero.
Step-by-step explanation:
If yeast is placed into boiling water to make a yeast suspension, the extreme heat would denature the yeast's enzymes, essential for respiration and fermentation. Yeast cells operate within a specific temperature range, and boiling temperatures exceed the upper limit of this range, leading to the proteins losing their structure and function. Consequently, the rate of respiration in yeast would drop effectively to zero because the yeast cells would be killed by the heat, stopping all metabolic activity.
Yeast is known for its ability to perform alcoholic fermentation in the absence of oxygen, producing ethanol and carbon dioxide as byproducts. This process is used in bread dough to cause it to rise due to the formation of carbon dioxide gas bubbles. However, in the context of extreme heat as in boiling water, this fermentation process would not occur because the necessary enzymes would be inactivated.