Question

1. Prepared slides of a hyacinth root tip specimen was also examined with a microscope. The number of cells per zone and the total number of mitotic figures per zone (that is, cells that are in prophase, metaphase, anaphase, or telophase) were recorded. Calculate the length of each zone (in mm and to two decimal places) and the Mitotic Index (M.I.) to one decimal place. Your lab manual shows how to determine the length of each zone in the root tip. 4 marks

          M.I. = number of mitotic figuresx 100

                                                          total number of cells

Zone Number	Total number of cells	Total number of mitotic figures	Distance of zone from the root tip (in mm)	Mitotic Index
1	51	3	0.43	5.88
2	62	20	0.86	32.26
3	58	39	1.29	67.24
4	41	16	1.72	39.02

1. In a plant root, which zone had the most mitotic activity? Which had the least? Why? 4 marks

Answer 1

The four regions are root cap , Zone of division , zone of elongation and zone of maturation .

Of all the four zones in the zone of division maximum cell division will be found with maximum mitotic index

Greater mitotic index shows maximum cell division.

Reason for high mitotic index in zone of cell division:

The zone of cell division has Apical meristematic tissue , the characteristic feature of apical meristem tissue to show rapid proliferation. Meristem are actively dividing tissues . So maximum mitotic index is seen.

And in the cap region where quiescent centre is located ​​​​​,the cell division is very slow quiescent word itself indicates dormant or resting condition where the division process is slow , so the mitotic index in this region is low .