A student investigates the breakdown of starch by amylase at a fixed temperature and pH.
At regular intervals, the student tests a sample with iodine solution and judges by eye when the iodine first stays orange-brown. The student could use a colorimeter to assess the colour of each sample.
Why would using a colorimeter improve the measurement of the end point?
It records the time of the end point more precisely than a stopclock.
Its readings are precise enough that each test only needs to be done once.
It gives a numerical colour reading, reducing variation caused by personal judgement.
It finds the concentration of amylase from the final colour of the iodine.
184 exam-style questions on OCR GCSE Biology 1.2 What happens in cells (and what do cells need)?, covering 1.2.1 Structure of DNA, 1.2.2 Nucleotides and complementary bases, 1.2.3 Protein synthesis, 1.2.4 DNA structure and the proteins made, 1.2.5 Investigating enzymatic reactions, and 1.2.6 Mechanism of enzyme action. Each one has a worked solution and a mark scheme showing where the marks go.