State the four ways in which saliva is useful to us.

The four ways in which saliva is useful to us are:

1. It moistens and lubricates the mouth cavity and the tongue to make speaking and swallowing easy.
2. It cleans the mouth and destroys germs.
3. The saliva binds the food particles and makes it into a mass called the bolus.
4. Digestion begins in the mouth. Saliva contains an enzyme (amylase) which helps in the breakdown of starch to simple sugars (maltose).