What Happens in Cells (& What do Cells Need?) (OCR GCSE Biology A (Gateway))

Fermentation involves enzymes that break down sugar releasing carbon dioxide gas.

The volume of carbon dioxide released can be used to measure how fast these enzymes are working.

A student investigates if fermentation works faster at 25°C or 30°C.
She measures the volume of carbon dioxide released in 10 minutes.
The diagram shows the apparatus she uses.

The student could have measured the volume of carbon dioxide by collecting the gas over water in a measuring cylinder.

Why is it better to use a gas syringe?

The student’s results are shown in the table.

(i) Calculate the mean rate of gas produced at 25°C in cm³/minute.

Give your answer to 1 decimal place.

Mean rate of gas produced at 25°C = .................. cm³/minute [3]

(ii) The rate of gas produced at 30°C is greater than at 25°C. Use ideas about enzymes to explain why.

[3]

Phenols are chemicals that inhibit enzymes during fermentation.

They bind to amino acids on enzyme molecules.

Suggest how phenols inhibit enzymes.