Neco 2023 Biology Question 4

Students investigated the effect of temperature on the rate of respiration in *Saccharomyces cerevisiae* (baker's yeast) using a closed respirometer. The procedure was as follows: 1. 5 g of dried yeast was added to 100 ml of 5 % (w/v) glucose solution in a 250 ml sealed flask. 2. The flask was connected to a gas syringe that was initially set to 0 ml (zeroed). The system was placed in a water bath. 3. The flask was first kept at 30 °C for 30 minutes; the volume of gas displaced was recorded. 4. The temperature was then raised to 40 °C and the flask was kept for a further 30 minutes; the cumulative gas volume was recorded. The observations were: - After 30 min at 30 °C, the gas syringe read 45 ml. - After a further 30 min at 40 °C (total 60 min), the gas syringe read 120 ml. Assume the gas collected is CO₂ and that the mass of yeast remains constant throughout the experiment. Answer the following: