Name any two types of cells that act as 'cellular barriers' to provide innate immunity in humans.

Indiscriminate diagnostic practices using X-rays etc., should be avoided. Give one reason.

Why sharing of injection a needle between two individuals is not recommended?

A team of students are preparing to participate in the interschool sports meet. During a practice session you find some vials with labels of certain cannabinoids.

(a) Will you report to the authorities? Why?

(b) Name of a plant from which such chemicals are obtained.

(c) Write the effect of these chemicals on human body.

A student on a school trip started sneezing and wheezing soon after reaching the hill station for no explained reasons. But, on return to the plains, the symptoms disappeared. What is such a response called? How does the body produce it?