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| Question | Answer |
| Testing For Carbohydrates: Starch | To test for starch, add iodine solution to a sample. If starch is present, there will be a colour change of yellow-brown to blue-black. |
| Testing For Carbohydrates: Reducing Sugars (all monosaccharides and some disaccharides) | Heat the reducing sugar with Benedict's solution, there us a colour change from blue to green to yellow to orange-red depending on the concentration of the reducing sugar. |
| Testing For Carbohydrates: Non-Reducing Sugars | Test a sample for reducing sugars to check there are none in the first place. Take a seperate sample and boil it with hydrochloric acid to hydrolyse the sucrose. Cool the solution and use sodium hydrogencarbonate solution to neutralise it, test for reducing sugars again. A positive result of green-yellow-orange- red signifies that non-reducing sugar was present |
| Testing for Lipids | By using the emulsion test; thoroughly mix the sample with ethanol, filter it, pour the solution into water in a clean test tube. A cloudy white emulsion indicates the presence of lipids (due to tiny lipid droplets coming out of solution when mixed up with water). |
| Testing For Proteins | Use the biuret test.. First add biuret A (Sodium Hydrocide) and then biuret B (Calcium Sulfate). If protein is present there will be a colour change from light blue to lilac (tests for peptide bonds). |
| Quantitative Test For Reducing Sugars | If there is more sugar the amount of precipitate increases as the amount of copper ions in solution decreases. The concentration of sugar is assessed by a colorimetry. With more reacted copper sulfate the supernatant is less blue, absorption of red light is low, percentage transmission is high. Use a blank sample in between to reset absorption. |
| Biosensors | They take a biological or chemical variable which cannot easily be measured, and convert it to electrical signals. Can be used to detect conntaminants in water, and pathogens/toxins in foods, as well as detecting airborne bacteria. |
| Chromatography | The aim is to separate a mixture into its constituents- biological molecules. Two phrases involved: stationary (chromatography paper made of celluose), mobile (the solvent, usually ethanol or water, as this solvent flows through and across the stationary phase the biological molecules flow through it) |
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