(a) With the help of an activity, explain the action of saliva on the food we eat. (b) Why is bile juice important in the process of digestion?

(a) The action of saliva on food can be demonstrated through a simple activity:

• Take two test tubes, A and B.
• In test tube A, add one teaspoon of boiled rice.
• In test tube B, add one teaspoon of boiled rice that has been chewed for 3 to 5 minutes.
• Add 3.4 mL of water to both test tubes.
• Add a few drops of iodine solution to each test tube.

Results:

• In test tube A, the rice changes colour due to the absence of enzymes.
• In test tube B, there is no colour change because the amylase enzyme in saliva breaks down the starch into simple sugars.

(b) Bile juice plays a crucial role in digestion:

1. It breaks down fats into fatty acids, making them easier to absorb.
2. Bile also provides an alkaline fluid that neutralises the acidic food from the stomach.