Which essential mineral element plays a significant role in both respiration and nitrogen metabolism in plants?

Which mineral is essential for the repair of worn-out cells in our body?

Calcium gets accumulated in which of the following?

Tryptophan synthesis,carboxylase activity,and little leaf of plants are all associated with:

Mark the statements as true/false by choosing the correct option from the set $(I-IV)$ given below:
$I.$ Magnesium is a constituent of chlorophyll and helps to maintain the ribosome structure.
$II.$ Calcium is needed during the formation of mitotic spindle.
$III.$ Magnesium is essential for the photolysis of water.
$IV.$ Zinc helps in sugar translocation.

Which mineral element is present in enzymes involved in the metabolism of carbohydrates,fats,and proteins?