Why is that in certain plants deficiency symptoms appear first in parts of the plants while in others, they do so in mature organs?

Explanation

When deficiency symptoms appear first, we can notice the diffferences in old and younger leaves. It is mainly due to mobility of minerals . Besesd on this, they are classifiedinto minerals . Besed on this , they are classified into 1. Actively mobile mineals and 2. Relatively immobile minerals
(a) Actively mobile minerals : Nitrogen , phosphorus , potassium magnesium,chlorine,sodium,zinc and molybdenum. Deficiency sympotoms first appear on old and senesenescent leaves due to active movement of minerals to younger leaves.
Relatively immoblie minerals: Calcium ,sulphur, Iron, bron and copper, here, deficiency symptoms first appear on young leaves due to the ommobile nature of minerals .