Anaerobic respiration in yeast cells involves a series of enzyme-controlled reactions that break down sugars, releasing carbon dioxide gas as a waste product. The volume of carbon dioxide released can be monitored to determine the rate of respiration.
A student investigated the effect of temperature on the rate of respiration in a strain of baker's yeast (Saccharomyces cerevisiae). They measured the volume of carbon dioxide gas produced over a period of 16 minutes at 24∘C24^\circ\text{C}24∘C and 29∘C29^\circ\text{C}29∘C using a gas syringe.
Explain why using a gas syringe to collect the gas is more suitable than collecting it over water in an inverted measuring cylinder.
The student's measurements are recorded in the table below:
| Temperature (∘C^\circ\text{C}∘C) | Volume of carbon dioxide gas (cm3\text{cm}^3cm3) released in 16 minutes | ||
|---|---|---|---|
| Trial 1 | Trial 2 | Trial 3 | |
| 24 | 51 | 56 | 52 |
| 29 | 73 | 79 | 76 |
(i) Calculate the mean rate of carbon dioxide gas produced at 24∘C24^\circ\text{C}24∘C in cm3 min−1\text{cm}^3\text{ min}^{-1}cm3 min−1. Give your answer to 1 decimal place. Show your working.
The rate of gas production at 29∘C29^\circ\text{C}29∘C is higher than at 24∘C24^\circ\text{C}24∘C. Use kinetic theory and your knowledge of enzymes to explain why.
Heavy metal ions, such as silver ions (Ag+\text{Ag}^+Ag+), can act as non-competitive inhibitors of key respiratory enzymes by binding to a site away from the active site. Suggest how this inhibits the enzyme's activity.