Biological Molecules & Food Lab

1) The positive and negative results were different for all three tests that took place last class. A lipid test would be positive if there was a stain left on the paper from when you rubbed the food item against it. A starch test would be positive if the food item turned black once it came in contact with the chemical. A glucose test would be positive if the items in the test tube changed to orange or yellowish colour after being heated for about two minutes.

2)

 

Glucose is the building block that starch molecules are made up of.

3) I think that all the test tubes indicated a positive result at the end of the additional two minutes because the carbohydrate molecules received the additional time they required to break down and release the simple sugars known as glucose. 

4) The Journey Of A Cupcake From The Start To The End:
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 cupcake. 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 cupcake 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 cupcake 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.