You are aware of the $Polio$ $Eradication$ $Programme$ in your city. Children are vaccinated because:

What do you mean by active and passive immunisation?

$(a)$ Why do parents immunize their newborn babies?
$(b)$ What are the ways to prevent mosquitoes from breeding?

Raju of Class $IX$ was suffering from chickenpox. His friends Priya and Shaurya wanted to visit him. Shaurya's parents did not allow him to go. Priya had already suffered from it a few months before. Priya's parents allowed her to visit him. What could be the reason behind their parents' decision? What is the basis of the principle of immunisation?

State whether the following statement is true or false:
Antibiotics commonly block biochemical pathways important for bacteria. However,viruses do not use these pathways at all,which is the reason why antibiotics do not work against viral infections.

List four preventive measures against communicable diseases.