Digestion Lab: Day 2

When we returned to science class today, not much from our lab had changed. In test tube A, the pepsin had crystallized around the egg whites. The pepsin in test tube B had dissolved into the water and made it foggy. Test tube C still had no reaction. Test tube D had the most change. The egg whites had shrunk a little bit and there were bubbles. The materials that were best at breaking down the egg were the hydrochloric acid and pepsin. Alone, the pepsin did not do much to break down the egg white.  Hydrochloric acid, alone, also did not do much. Together, they had broken down the egg a little bit. In the end of the lab I concluded that the chemical digestion of protein in food is a slow reaction. This is my conclusion because none of the test tubes had broken down the egg whites.

Digestion Lab: Day 1

Today in science class we began a lab. This lab was about the human digestive system’s way of breaking down food. When doing this lab we used hydrochloric acid, pepsin, boiled egg whites, and water. The hydrochloric acid represented the acid in our stomach that helps break down food. The boiled egg whites represented the food in our stomach. First, we placed egg whites and pepsin in test tube A. After a few minutes the egg whites started turning a light yellow color. Next, we put water, pepsin, and egg whites in test tube B. The water sat at the top while the pepsin sank to the bottom of the test tube. Then, we placed only egg whites and hydrochloric acid in test tube C. There was no immediate reaction in test tube C. In test tube D we put hydrochloric acid, pepsin, and egg whites. The mixture inside the test tube bubbled a little. I predicted that the next day, test tube D would have been the only test tube that had broken down egg whites in it. In the end, we used litmus paper to test the presence of an acid. Litmus paper turns pink when it touches an acid such as hydrochloric acid. Test tubes A and B tested negative for acid, but test tubes C and D tested positive for acid.