1. We used a variety of foods for this test, namely tomato, cheese, cupcake, lettuce, bread, apple, orange, carrot, and pancake. For the simple sugars test, tomato and carrot tested positive.
Cupcake, bread, and pancake tested positive for starch; tomato and cheese had a few specs of black which showed the reaction between the starch and iodine.
Butter, cupcake, and bread tested positive for lipids.
2. The building blocks of starch molecules is glucose. Glucose polymers are made up of Amylose and Amylopectin. When water is added, starch breaks down into glucose molecules. The following is an image of the molecular structure of starch (I hope D:):
3. Simple carbohydrates digest or break down into sugar quickly. The reason some test tubes needed to remain in the hot water bath longer before turning a cloudy orange or yellow, is because the more complex a carbohydrate is, the longer it takes to break down.
4. Starting at the mouth, using our teeth and tongue, we chew up food to increase surface area, therefore making the process of digestion slightly easier. As we chew, salivary amylase is secreted, which digests complex carbohydrates. The bolus of food is then sent to the back of the mouth, through the pharynx, and into the esophagus. The bolus makes its way down to the stomach through muscle contractions called peristalsis, which can be found throughout the entire digestive tract. Upon making it through the cardiac sphincter, and reaching the stomach, the bolus experiences more mechanical digestion, along with chemical digestion, with the help of gastric juice, composed of hydrochloric acid, mucus and the enzyme pepsin. The pH inside the stomach is 2, which is why mucus is an essential component of the stomach; it lines the stomach walls to prevent corrosion due to the HCl. Proteins begin to digest in the stomach. The food (chyme) then passes through the pyloric sphincter, into the duodenum. This is where the accessory organs, the liver, gall bladder, and pancreas, come into play. The pancreas has pancreatic juice, containing pancreatic amylase, trypsin, lipase, nuclease, and sodium bicarbonate; it also produces insulin and glucagon. The liver produces bile, and the gall bladder stores it. The pancreas secretes sodium bicarbonate as the food enters the duodenum, so the acid from the stomach is neutralized and does not harm the small intestine. Bile from the liver is also received by the duodenum. In the small intestine we are introduced to nucleosidase, maltase, and peptidase; these make up small intestine juice. Also present in the small intestine are villi and microvilli; they increase surface area, thus increasing the absorption rate of nutrients. The matter then makes its way in to the large intestine, passing the appendix; the job of the large intestine is to absorb water. The large intestine also contains E.Coli, which is an essential bacteria for our protection. At this point the chyme has become feces, and is ready to make its way through the rectum, anus, and anal sphincter, subsequently ending the process of digestion.
That's all, folks.
