Chemical Digestion - Lab Activity

SBI 3U

Ms. GirvanDate: ______

Chemical Digestion - Lab Activity

Purpose: The purpose of this lab is to predict and analyze the results of mixing different types of foods with three digestive compounds (amylase, pepsin and bile salts).

Set-up:

Each of the following foods was treated separately with the three digestive compounds:

Soda crackers
Rice cakes
Cooked pasta
Cooked ground beef
Processed ham
Boiled egg
Processed cheese
Vegetable Oil

In the chart below predict whether you expect to observe chemical digestion:

Digestive Compound / Soda Cracker / Rice Cakes / Pasta / Ground Beef / Ham / Egg / Cheese / Oil
Salivary Amylase
Pepsin
Bile Salts

After you have made your predictions examine the observation sheets. In the results section, state whether chemical digestion has occurred for each food? If the answer is not what you expected, give a reason why.

Observations:

Soda Cracker / -liquid solution
-same colour as crackers
-slimy
-crackers are dissolved in saliva and no longer solid
Rice Cakes / -liquid solution
-same colour as rice cakes
-slimy
-cakes dissolved in saliva and no longer solid
Pasta / -liquid
-slimy
-pieces of pasta have broken off into solution
Ground Beef / -no changes in the beef
-solution is clear and colourless
Ham / -no changes in the ham
-solution is clear and colourless
Egg / -no changes in the egg
-solution is clear and colourless
Cheese / -no changes in the cheese
-solution is clear and colourless
Oil / -no changes in the oil
-solution is clear and colourless
-solution in 2 phases

Table #1: Observation of substances after addition of salivary amylase.

Soda Cracker / -cracker is still mostly sold
-not as solid as before
Rice Cakes / -cake still mostly solid
-not as solid as before
Pasta / -small particles of pasta in solution
-clear, colourless solution can still be seen
Ground Beef / -ground beef is still solid
-particles are present
-clear, colourless solution can still be seen
Ham / -no change in ham
-clear, colourless solution
Egg / -yellow solution, with small egg white particles
Cheese / -little change in cheese
-some particles of cheese in solution
-clear, colourless solution can still be seen
Oil / -2 phases
-oil is on top of clear, colourless solution

Table #2: Observation of substances after addition of pepsin.

Soda Cracker / -solid cracker
-brown
-no liquid
Rice Cakes / -solid cake
-brown
-no liquid
Pasta / -solid pasta
-brown solution
-small particles in solution
Ground Beef / -solid beef
-many particles in brown solution
Ham / -brown solid ham
-some particles in brown solution
Egg / -brownish-yellow solution with small egg white particles
Cheese / -brown cheese in brown solution with many particles
Oil / -one phase
-brown
-liquid

Table #3: Observation of substances after addition of bile salts.

Results:

Result #1: Salivary Amylase (4 marks, ½ each)

Soda Cracker
Rice Cakes
Pasta
Ground Beef
Ham
Egg
Cheese
Oil

Result #2: Pepsin (4 marks, ½ each)

Soda Cracker
Rice Cakes
Pasta
Ground Beef
Ham
Egg
Cheese
Oil

Result #3: Bile Salts (4.5 marks, ½ each)

Soda Cracker
Rice Cakes
Pasta
Ground Beef
Ham
Egg
Cheese
Oil

Discussion:

(Hint: You may need to refer to your textbook for some of the answers)

1. Each of the foods were mechanically digested before adding any enzyme. Why was this necessary? (1 mark)

2. Which organ makes salivary amylase? (1 mark)

3. What does salivary amylase break polysaccharides down into? (1 mark)

4. Where does this reaction occur? (1 mark)

5. The pepsin enzyme was prepared in a slightly acidic solution. Why was this necessary? (1 mark)

6. What macromolecule does pepsin digest? (1 mark)

7. What organ makes pepsin? (1 mark)

8. When does pepsin stop working? Why? (2 marks)

9. What macromolecules do bile salts digest? How? (2 marks)

10. What organ makes bile salts? (1 mark)