Bread Lab Energy Transformations in the Bread Lab

This is how your notebook will look at the end of the lab. In today’s activity, you will be diagraming each step and labeling your diagram.

Digestion is a physical and chemical process. The energy transformation that occurs during digestion is: chemical  thermal Record this information in your journal.

Torn bread represents teeth tearing food. (P) Step 1:

Water added represents saliva. (C) Bread is gently mashed representing chewing (P) Step 2:

This is what your notebook should look like at this point. Remember to draw arrows between sketches. Torn bread represents teeth tearing food. (P) Water added represents saliva.(C) Bread is gently mashed representing chewing (P)

Step 3: Bile from the liver and pancreatic juices are added to the nutrients in the small intestine (C). The intestines squeeze and push the nutrients along (P).

Also record observations of any color, temperature, and other changes you may observe in your journal.

The wastes are moved into the large intestine where excess water is squeezed out and recycled into the bloodstream. (P) Similar to absorption of nutrients in the small intestine Wastes Absorption of water Step 4:

The solid wastes are held in the rectum and excreted through the anus (P). Large intestine Anus Waste Rectum Step 5:

During chemical digestion, complex carbohydrates like starch are broken down into simper carbohydrates like sugar, which are small enough to be absorbed into the bloodstream. Chemical  Thermal Energy Transformation Explained: Smaller Molecules Starch Sugars Amino acids When bonds are broken, HEAT is released. Large Molecules Protein Fat Glycerol & fatty acids

Conclusion: Answer the following in your journal in complete sentences: 1. What did this action of tearing the bread into pieces represent in digestion? Label as physical or chemical. 2. Why were the drops of water added to the bag? 3. After adding the digestive juices to the bag and gently mashing the contents, what change in temperature did you observe? Change in state of matter (solid, liquid, gas)? 4. What type of energy transformation is taking place when the bread is mashed with the digestive juices? (HINT: think about the temperature change!) 5. Why is it necessary for large molecules to be broken down into smaller molecules?