3 questions of nutrition in animals

Why do we get instant energy from glucose?

Glucose is a simple sugar. It easily breaks down in the cell with the help of oxygen and provides instant energy to the organisms, glucose does not need digestion. Hence, when glucose is directly taken, it does not get digested and acts as an instant source of energy.

What do you understand by rumen and rumination?

When you ruminate you chew something over, either literally or figuratively. Literal rumination may seem a little rumination, but to cows, chewing your cut (that's partially digested food brought up from the stomach for another chow) is just a natural part of life.

How many pairs of salivary glands are present in human and what is the function of saliva?

The are through which most of the saliva is secreted and symmetrically located on both sides of the jaw. They secrete saliva through ducts. These glands are sublingual.