Which of the following mineral deficiencies will cause death of stem and root tips?
a)	Mo	b)	Ca	c)	S	d)	Fe

(b)

Calcium involved in selective permeability of cell membranes. It activates certain enzymes required for development of stem and root apex and as calcium pectate in the middle lamella of cell wall. The deficiency of calcium causes stunted growth, degeneration of meristems especially root apex, chlorosis, necrosis and curling.