Fermentation involves enzymes that break down sugar, releasing carbon dioxide gas. The volume of gas released can be used to measure the rate of fermentation.
A student investigates how temperature affects the rate of fermentation in yeast. They measure the volume of carbon dioxide released over 15 minutes at 30∘C30^\circ\text{C}30∘C and 35∘C35^\circ\text{C}35∘C using a gas syringe.
Explain why using a gas syringe to collect the gas is better than collecting it over water in a measuring cylinder.
The student's results are shown in the table below:
| Temperature (∘C^\circ\text{C}∘C) | Volume of carbon dioxide gas (cm3\text{cm}^3cm3) released in 15 minutes | ||
|---|---|---|---|
| Trial 1 | Trial 2 | Trial 3 | |
| 30 | 38 | 41 | 41 |
| 35 | 51 | 47 | 52 |
Calculate the mean rate of gas produced at 30∘C30^\circ\text{C}30∘C in cm3/minute\text{cm}^3/\text{minute}cm3/minute. Give your answer to 1 decimal place. Show your working.
The rate of gas produced at 35∘C35^\circ\text{C}35∘C is greater than at 30∘C30^\circ\text{C}30∘C. Use ideas about enzymes and kinetic theory to explain why.
Heavy metal ions can act as non-competitive inhibitors by binding to a site on the enzyme away from the active site. Suggest how this inhibits the enzyme.