A respirometer is a piece of apparatus that can be used to measure the rate of respiration of living tissue such as germinating peas. A simple respirometer is shown in Fig. 6.1. [Figure 6.1] A student carried out an investigation to determine the effect of temperature on the rate of respiration of germinating peas. • The student set up the respirometer as shown in Fig. 6.1 and placed the respirometer in a water-bath at 10°C. • After five minutes, the student used the syringe to adjust the position of the coloured liquid in the right-hand side of the U-shaped tube so that it lined up with 0 cm on the ruler. • The student immediately started a timer. • The germinating peas used up oxygen, causing the coloured liquid in the U-shaped tube to move. • The student measured the distance moved by the coloured liquid after 20 minutes. • The student repeated the experiment at temperatures of 20 °C, 30°C, 40°C and 50°C.