Which of the following are trace elements?

$S$ - Statement: Sulfur is present in the structure of cysteine and methionine amino acids.
$R$ - Reason: Phosphorus does not participate in energy exchange processes.

Which element shows the given characteristics?
$(i)$ It maintains an anion-cation balance in cells.
$(ii)$ It is also involved in protein synthesis.
$(iii)$ It is required for the opening and closing of stomata.
$(iv)$ It is required for the maintenance of the turgidity of cells.

Which of the following is a structural component of vitamins like biotin and thiamine?

Copper is a component of:

$Ca^{2+}$ is an essential element in plants. The major function it performs is