It is observed that deficiency of a particular element showed its symptoms initially in older leaves and then in younger leaves.
(a) Does it indicate that the element is actively mobilised or relatively immobile ?
(b) Name two elements which are highly mobile and two which are relatively immobile.
(c) How is the aspect of mobility of elements important to horticulture and agriculture ?

Explanation

Symptoms of deficiency of mobile elements are more pronounced in older leaves and symptoms of deficiency of relatively immobile element appear first in younger leaves. This information can be utilised by horticulturist and agriculturist to get a broad idea of the deficiency elements in plants.