A technician tests a glucose solution for contamination by microorganisms.
Equal volumes of the solution are placed in two identical insulated containers. Disinfectant is added to container D and an equal volume of water is added to container U. The disinfectant does not release heat. Both containers are fitted with loose cotton wool plugs and kept under the same conditions for 24 hours.
| Container | Treatment | Temperature at start (°C) | Temperature after 24 hours (°C) |
|---|---|---|---|
| D | Disinfectant added | 20.0 | 20.2 |
| U | Water added | 20.0 | 24.0 |
A technician concludes that the glucose solution was contaminated by microorganisms. Explain whether the results support this conclusion.
113 exam-style questions on OCR GCSE Biology 1.3 Respiration, covering 1.3.1 Cellular respiration supplies ATP, 1.3.2 Aerobic and anaerobic respiration, 1.3.3 Sugars and carbohydrates, 1.3.4 Amino acids and proteins, and 1.3.5 Fatty acids and lipids. Each one has a worked solution and a mark scheme showing where the marks go.