Ijmb Model Questions Vol1 2018 Biology Question 4

Students investigated the effect of sugar concentration on the rate of cellular respiration in baker's yeast. The procedure was: 1. Prepare three fermentation broths (250 mL each) containing 0 % (control), 2 % (w/v) and 5 % (w/v) glucose respectively. 2. Add 5 g of active dry yeast to each broth, seal the flask with a rubber stopper fitted with a graduated gas‑collecting tube (water displaced), and place the flasks in a water bath at 30 °C. 3. After 30 min, record the volume of CO₂ collected (mL) in each tube. Three independent trials were performed for each concentration. The recorded volumes are: | Glucose concentration | Trial 1 | Trial 2 | Trial 3 | |-----------------------|--------|--------|--------| | 0 % (water control) | 0.2 | 0.1 | 0.15 | | 2 % | 1.8 | 1.9 | 1.7 | | 5 % | 1.2 | 1.1 | 1.3 | Using the data above, answer the following: