Waec Model Questions Vol1 2019 Biology Question 4

Students investigated the effect of temperature on the rate of respiration in germinating mung bean seeds using a closed respirometer. Five seeds were placed in a sealed 250 ml flask containing a drop of water. The flask was connected via a graduated tube to a water‑filled inverted burette to collect the volume of CO₂ produced (shown as a decrease in water level). The water bath temperature was maintained at either 20 °C (control), 30 °C or 40 °C. The volume of gas collected was recorded at 0, 5, 10 and 15 min for each temperature as shown in the table. | Temperature (°C) | 0 min (ml) | 5 min (ml) | 10 min (ml) | 15 min (ml) | |------------------|------------|------------|-------------|-------------| | 20 | 0 | 4.2 | 8.1 | 12.0 | | 30 | 0 | 6.5 | 13.0 | 19.5 | | 40 | 0 | 9.0 | 18.5 | 27.5 | Assume the volume change is directly proportional to the amount of CO₂ produced.