What is a centromere? How does the position of centromere form the basis of clasification of chromosomes. Support your answer with a diagram showing the position of centromere on different types of chromosomes.

Classify the chromosomes based on the position of centromere.

Chromosomes at anaphase are of various shapes depending upon position of centromere. It is J shaped when centromere is

[A]: Metacentric chromosomes are V-shaped [R]: In these chromosomes, the centromere occurs in the centre forming two equal arms.

Analyse the observation table which shows variation of image distance [v] with object distance [u] in the case of a convex lens. Answer the questions that follow without doing any calculations. {:("Sl.No","Object distance","Image distance"),(,"u [cm]","v [cm]"),(1,-90,+18),(2,-60,+20),(3,-30,+30),(4,-20,+60),(5,-18,+90),(6,-10,+100):} (a) What is the focal length of the convex lens ? Given reasons to support your answer. (b) Write the Sl.No of the observation which is not correct. How did you arrive at this conciusion ? (c ) Use an appropriate scale to draw the ray diagram for the observation at Sl. No 4 and find the approximate value of magnification.