Starches, Lipids, and Sugars Lab

On Friday we completed a lab testing different food samples for the presence of lipids, starch and simple sugars.  You can post your observation pictures and results chart(s) to your blog and then work on the following lab questions to post as well.
QUESTIONS
1.  Describe a positive result for each of the tests that you performed in the lab.

For a positive test on lipids, we looked for smuding on the paper. If the smudge was see through, then the result was positive for lipids. To find a positive result for starch, the food had to turn black after putting a few drops on iodide on the food. For the simple sugar, the food tested postitive if the test tube changed from a clear, blue liquid, to a yellow/orange opaque liquid. 

2.  Starch molecules are large carbohydrate polymers.  Find and post an image of the molecular structure of starch.  What are the building blocks that starch molecules are made of?

Starch molecules are made up of glucose.

3.  Thomas and Josh had interesting results to their simple sugar test - if you are following either of their blogs, look at their picture of their test tubes after they took them out of the hot water bath.
After 2 minutes, only 2 of the test tubes were yellow/orange, and the rest remained blue.  They took the two positive test tubes out of the hot water bath and left the others in the hot water bath for 2 more minutes.  At the end of the two extra minutes all the test tubes indicated a positive result.  Based on your knowledge of carbohydrate molecules, why do you think they got these results? 

Due to the heat of the hot water, the food slowly got broken down. Since carbohydrates are made up of glucose, eventually the were broken and became positive for glucose.

4.  Making connections - Describe the passage of one of your food items through the digestive system, starting with the mouth & ending at the anus.  Include the specific enzymes, accessory organ secretions & internal conditions the food/chyme would pass through from start to finish.

After taking a bit out of an bread, your teeth start breaking down the chunk into tiny pieces while the tongue moves the food into the appropriate teeth. Salivary glands also start to produce salivary amylase, and chemically break down the bread. The salivary amylase breaks down the starch in the bread, to maltose. The food, or bolus, which is it now called, goes down the esophagus via peristaltic contractions. From the esophagus, the bolus goes through the cardiac sphincter and enters the stomach. the food is stored there, and the hydrochloric acid turns the bolus into chyme. After that, peristalsis moves it from the stomach, through the pyloric sphincter and enters the duodenum. In the duodenum, the maltose breaks down into the monomer glucose. The small intestine is structured in finger like projections called villi, which maximize the surface area for absorbing the nutrients from the food. The food then goes through the large intestine, where it is stored and water is absorbed. The food (now called feces) is stored in the large intestine until it is ready to be passed through through the rectum, and out the anus, using the anal sphincter. 

RESULTS
        Positive for:     Starch.                           Lipids.                      Simple Sugars

1. Bread.            Yes.                               No.                                 Yes
2. Tomato.          No.                                No.                            Not used
3. Lettuce.          No.                               No.                                   No
4. Orange.         No.                                No.                              Not used
5. Pancake.        Yes.                              No.                                  Yes 
6. Cheese.         No.                                 No.                                  No 
7. Butter.            No.                               Yes.                             Not used
8. Apple            No.                                No.                                 Yes
9. Cupcake.       Yes.                               Yes.                               No

OBSERVATIONS

Simple Sugars Result