Explain the terms chlorosis and necrosis.

(N/A) $\Rightarrow$ Chlorosis is the loss of chlorophyll,which leads to the yellowing of leaves.
$\Rightarrow$ This symptom is caused by the deficiency of elements $N, K, Mg, S, Fe, Mn, Zn$,and $Mo$.
$\Rightarrow$ Necrosis refers to the death of tissues,particularly leaf tissue.
$\Rightarrow$ It is caused by the deficiency of $Ca, Mg, Cu$,and $K$.