A student carried out four tests for biological molecules on a sample of milk. The tests and their results were as follows. • Heating to 80 °C with Benedict's solution gave a brick red colour. • Adding Biuret solution gave a purple colour. • Adding iodine solution gave an orange colour. • Boiling with acid, followed by neutralisation, then heating to 80°C with Benedict's solution gave a brick red colour. Which biological molecules must be present in the milk? 1 non-reducing sugars, 2 protein, 3 reducing sugars, 4 starch