Study the diagram given below and answer the questions that follows.

(a) Name the parts labelled 1, 2 and 3 in the diagram.

(b) Mention the collective terms for the membranes covering the brain.

(c) What is the function of cerebrospinal fluid?

After examining a prepared slide under high power microscope, a student concludes that the given slide shows stage of mitosis. Write his observation on the basis of which this conclusion can be drawn.

'A' forms the outer portion of the kidney and 'B' form the inner portion of the kidney. Name A and B.

Define alleles.