(a) List five classes of food other than carbohydrates.
(b) Explain why glucose is taken by an athlete ready for a race rather than corn meal.
(c) Describe the test for starch.
Explanation
(a) Classes of food other than carbohydrates are: protein, fats and oils / lipids, water, vitamins, mineral salts.
(b) The reasons why glucose is taken by an athlete before a race are: glucose is the simplest form of carbohydrate, i.e. soluble form of cabohydrate; which does not require any form of digestion. Hence, it is absorbed in the ileum, small intestine, where it diffuses and enters into the blood stream, circulatory system. It is then assimilated and oxidized; within the shortest time to give energy to the athlete. But corn meal is a complex carbohydrate, polysaccharide, starch, which will require series of carbohydrate / hyrolysis, starting from the mouth and later in the duodenum. Due to the processes, carbohydrate has to pass through it to the small intestine, ileum, which takes a longer time to produce energy for use, i.e cannot give immediate energy.
(c) To test for starch, obtain tuber of yam, cassava, potato, sweet potato, maize, cereal or any starchy food and macerate (crush). Then, add water to the mash to prepare starch solution; put a few drops of the starch (mashed material or a bit of the macerate on a white tile) test tube or watch glass. Add one to two drops of iodine and the material or solution will turn blue black, or black indicating presence of starch.