Question

Explain an activity to show that saliva breaks down starch which is a complex molecule to give sugar

Answer 1

Saliva contains an enzyme called as Amylase which breaks down the amylose in starch into amylopectin. Amylase causes hydrolysis reaction and breaks down the starch particles into smaller particles, leading to the final production of simple carbohydrates like maltose, maltotriose, and dextrins.

Experiment to show the effect of saliva on starch:-

1. 2 test tubes labeled A and B are taken, where tube A contains 1 tsp of boiled rice and tube B has 1 tsp of rice which has been chewed for 3-5 mins.

2. 4 ml water is added to both the test tubes and then 2-3 drops of iodine solution is also added to each test tube.
 
The color in the tube A changes to bluish-black color, whereas the color in the tube B remains unchanged.

This is because the rice in the tube B has been chewed and the saliva has acted on it and broken down the starch molecules into smaller sugar particles. But, the starch in the tube A was not chewed so the starch molecules are intact in it. The starch reacts with the iodine to give a bluish-black color. This indicates the action of saliva on starch.

Answer 2

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