Question

Only two of the following statements accurately describe what happens in the mouth.
1. Amylase breaks down large starch molecules into smaller maltose molecules.
2. Chewing increases the surface area of food for digestion
3. Saliva emulsifies fats into smaller droplets.
4. Teeth breakup large insoluble molecules into smaller soluble molecules.
Which statements are correct?
A. 1 and 2
B. 2 and 3
C. 3 and 4
D. 1 and 4

Answer 1

The two correct statements are:

1. Amylase breaks down large starch molecules into smaller maltose molecules.

2. Chewing increases the surface area of food for digestion.

(option A. 1 and 2)

Let us analyze each statement.

1. Amylase breaks down large starch molecules into smaller maltose molecules.

Working of Amylase

• Amylase is an enzyme found in the saliva of the human mouth.
• It is responsible for the hydrolysis of starch.
• Almost 30% of the total starch digestion is facilitated by salivary amylase.
• It converts starch into maltose- a disaccharide- and dextrins(smaller carbohydrate forms).

2. Chewing increases the surface area of food for digestion

• Before the food is ingested into the digestive tract, it has to be broken down into smaller particles to allow movement in the tract.
• The food is broken down in multiple steps throughout its digestion. The first breakdown is in the mouth.
• Teeth are used to chew food into a more digestible form- the bolus.
• Bolus has more surface area to allow enzymes and digestive juices to act on it easily.

3. Saliva emulsifies fats into smaller droplets.

• As established in the explanation of statement 1, salivary amylase acts on carbohydrates, not proteins.
• Bile, in the liver, is responsible for the emulsification of fats into smaller droplets.
• Hence, this statement is incorrect.

4. Teeth break up large insoluble molecules into smaller soluble molecules.

• Teeth help in the breakdown of food particles.
• However, they do not necessarily make insoluble particles soluble.
• They only have the mechanical effect of breaking down and increasing the surface area of the food.
• Hence, this statement is incorrect.

Therefore, the correct option is A. 1 and 2.

Answer 2

Answer

Option A) 1 & 2

Explanation

Chewing increases the surface area of food. Large food particles are broken down into small fragments. Salivary amylase secreted by salivary glands acts on carbohydrates (starch) present in food and converts it into maltose. Saliva does not act on fats.