Fill in the blanks:
The rhythmic contraction and explanstion of heart is called............ .

What are the contraction and relaxation of the heart called ?

Rhythmical contraction is noticed in

The rhythmic expansion and contraction of the heart is called ______.

Fill in the blanks: The combination of two or more cells is called a ________.

Cardiac muscles undergo rhythmic contraction and relaxation throughout life.

Fill in the blanks: The process of obtaining and utilization of food by an organism is called.............. .

Fill in the blanks. The slow process of conversion of dead vegetation into coal is called__________.