Igcse Model Questions Vol1 2017 Biology Question 3

A student is investigating the effect of temperature on the activity of the enzyme amylase in breaking down starch. Five test tubes each containing 5 mL of 1 % (w/v) starch solution were prepared. To each tube 1 mL of amylase solution (concentration constant) was added and the mixture was incubated for 5 minutes at the temperatures shown in the table below. After incubation 1 mL of iodine solution was added and the colour intensity was recorded using the scale 0 = no colour (starch completely hydrolysed) to 5 = deep blue (starch present). The experiment was repeated three times for each temperature. | Temperature (°C) | Replicate 1 | Replicate 2 | Replicate 3 | |------------------|------------|------------|------------| | 10 | 4 | 3 | 4 | | 25 | 2 | 3 | 2 | | 37 | 0 | 0 | 0 | | 50 | 3 | 4 | 3 | | 70 | 5 | 5 | 4 | Using the data above, answer the following questions: