Q.The element which is not remobilized?

Minerals differ in how easily a plant can withdraw them from mature tissue and relocate them to younger, actively growing parts, and this mobility is what decides where a deficiency symptom first becomes visible. Actively mobile minerals - nitrogen, phosphorus, potassium, magnesium, chlorine, sodium, zinc and molybdenum - are readily translocated out of older, senescing leaves into younger leaves when supply runs short, so deficiency symptoms appear first on the oldest leaves, which are effectively sacrificed to protect new growth. Relatively immobile minerals - calcium, sulphur, iron, boron and copper - cannot be withdrawn and relocated once deposited, often because they become bound into structural components such as cell walls, so their deficiency symptoms appea …