Trypsin is a protease enzyme. A student compared the activity of trypsin from two different species: the Atlantic salmon, Salmo salar, and the domestic pig, Sus scrofa domesticus. [Figure 2.1] shows an Atlantic salmon and [Figure 2.2] shows domestic pigs. Atlantic salmon are fish and are ectothermic, which means that the internal body temperature fluctuates with the surrounding environmental temperature. The water temperature in the habitat of Atlantic salmon can decrease to -0.5°C. Domestic pigs are mammals and maintain an internal body temperature of approximately 38 °C. The student was provided with trypsin from Atlantic salmon, trypsin from domestic pigs and cubes of gelatine. Gelatine is made from the protein collagen. The student measured the time taken for the trypsin from each animal species to break down the gelatine cubes at 20°C. The student: • used 10cm³ of 5% trypsin solution from each animal species • placed each trypsin solution in separate test-tubes, maintained at 20 °C in a water-bath • placed a gelatine cube in each test-tube of trypsin solution • recorded the time taken to break down the gelatine cube in each test-tube. The student repeated this 12 times for each type of trypsin. The results of the experiment are shown in Table 2.1. Table 2.1 replicate | time taken to break down gelatine cube/seconds | Atlantic salmon | domestic pigs 1 | 125 | 130 2 | 121 | 127 3 | 128 | 134 4 | 119 | 128 5 | 132 | 135 6 | 125 | 130 7 | 131 | 132 8 | 127 | 128 9 | 126 | 128 10 | 131 | 137 11 | 131 | 133 12 | 129 | 131 mean | 127.1 | standard deviation (s) | 4.1 |