1. What is the role of teeth in our mouth?
The teeth are our main tools for breaking down the food in the mouth.
 
2. What is a taste bud? Draw to show the different taste zones on the tongue.
The tongue contains taste buds on its surface. There are four types of taste buds located at different parts of our tongue. They help us in recognizing whether the food is sweet, salty, sour or bitter.  

 
3. What happens to the food in the stomach?
After the food is chewed and turned into a pasty ball by the saliva, it is swallowed. From the mouth, the food goes into the stomach through the food pipe. Several digestive juices produced from the stomach mix with the food and digest it further. The stomach takes about four hours to digest the food. From the stomach, the food goes to the small intestine. More digestive juices are added here and the digestion of food is completed.
 
4. Define the following terms:
i) Saliva           ii)Glucose
 
i) Saliva is a liquid secreted by salivary glands in our mouth.
ii) Glucose is the simplest form of sugar.
 
5. Digestion begins in mouth. Explain .
When we eat food, it is broken down into very small pieces by the chewing action of our teeth. Digestion begins in the mouth. As teeth crush and grind the food, an enzyme in saliva begins breaking down the starches into sugar.The tongue helps in the movement of food inside the mouth. The food becomes wet when it mixes with saliva. Saliva heps in moistening the food and makes it a lump of pasty food which can be swallowed easily.
 
6. What happens to the food in the small intestine?
 When food from stomach  reaches small intestine, more digestive juices are produced here and the digestion is completed.
 
7. Bread tastes sweet when chewed for a while. Give reason .
Bread contains a lot of starch or carbohydrates. Saliva contains digestive juices. These digestive juices change the starch present in the bread into a simpler form of sugar called maltose. This maltose has a sweet taste.  
 
8. How tongue helps us to recognize different tastes of food?
The main function of the tongue is to taste food. The tongue contains taste buds on its surface. There are four types of taste buds located at different parts of our tongue. They help us in recognizing whether the food is sweet, salty, sour and bitter.
 
9. A person suffering from low sugar level is given glucose solution. Why?
When a person is suffering from low sugar level, glucose solution is injected into his body through a drip. This gives instant energy to the patient.
 
10. You should chew your food well before swallowing. Give reason.
When we eat food, it is broken into very small pieces by the chewing action of our teeth. The food becomes wet when it mixes with saliva, a liquid secreted by salivary glands in the mouth. Saliva helps in moistening the food and makes it a lump of pasty food which can be swallowed easily.
 
11. Define the following: i) Tongue, ii) Digestion
i) Tongue: The tongue is an elongated fleshy structure. It is fixed on its far side but free at the front.
ii) Digestion:  Breaking down of food into simple form is called digestion.

12. Label the different types of teeth in the given picture of jaw.

13. Label the parts of the digestive system.