Chlorosis is caused due to the deficiency of:

Apple fruit develops internal cork due to the deficiency of:

Deficiency of molybdenum causes:

Necrosis,or death of tissue,particularly leaf tissue,is due to the deficiency of ........

It is observed that the deficiency of a particular element shows its symptoms initially in older leaves and then in younger leaves. Does it indicate that the element is actively mobilized or relatively immobile?

Deficiency symptoms of mineral elements appear first in young leaves. - $P$
Deficiency symptoms of mineral elements appear first in senescent (older) leaves. - $Q$
$P$ and $Q$ are respectively: