A technician monitors a starch mixture treated with amylase during syrup production. At each time, a drop of the reaction mixture is added to iodine solution. The table shows the colour of the iodine solution. The rate is calculated using rate=1000t\text{rate} = \dfrac{1000}{t}rate=t1000, where t t\,t is the time in seconds for all the starch to be broken down.
Use the results to calculate the rate of this reaction, in s−1\mathrm{s^{-1}}s−1. Explain how the results show when all the starch has been broken down.
| Time / s | Colour of iodine solution |
|---|---|
| 0 | Blue-black |
| 20 | Blue-black |
| 40 | Blue-black |
| 60 | Orange-brown |
| 80 | Orange-brown |
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.