Biological Molecules & Food Lab

Biological Molecules & Food Lab

1.)  A positive result for lipids (fats) is that the paper would be glossy and not as opaque. A positive result for starch is that it would turn black. The positive result for glucose is that it turns a yellow/ orangey color.

2.) The building blocks of a starch molecule is made up of a glucose molecule.

3. Carbohydrate molecules are made up of glucose molecules, so when the carbohydrates are heated up they break up

4. The four stages of digestion are ingestion, digestion, absorption, and elimination. Ingestion is the process of putting the food or drink into your mouth and digestion begins as soon as you start chewing the cookie. Mechanical digestion is when you use your teeth and tongue to chew your food until it id small enough to swallow. The little ball of food that you swallow is called a bolus which is covered with saliva in order to make the journey easier. Chemical digestion occurs because of an enzyme found in your saliva which helps speed up a chemical reaction. This enzyme is called amylase and it breaks down the bolus by breaking down the complex carbohydrates into simple carbohydrates or sugars. Once the cookie is swallowed it passes through the pharynx which is where the airway passage and digestive system meet. The airway tube is covered by a flap of flesh called the epiglottis. This flap covers the airway for when you swallow. The cookie then makes it way to the esophagus which connects the pharynx to the stomach. Food is then propelled through by a process called peristalsis which is caused by the contractions of muscles. Once in the stomach gastric juices called HCL, mucus, and pepsin break down the bolus into a liquid called chyme. There are two muscles at each end of the stomach called sphincters; these are round muscles that open to let things through. Once the chyme makes it through the sphincter it enters the small intestine and the second stage of digestion is complete once food leaves the duodenum, the first meter of the small intestine. Once through the duodenum digestion is complete and nutrients can be absorbed in the small intestine. The small intestine is covered in little folds called villi which provides more surface area and increases the rate of absorption. It takes about five to six hours to move from the small intestine into the large intestine. The large intestine takes undigested materials from the small intestine and reabsorbs water and minerals. The process of peristalsis occurs here once again and this time it takes about twelve to twenty-four hours. Any undigested materials leaving the large intestine are now considered as feces. This waste is stored in the rectum until it can be eliminated through the anus.