Which of the following elements is a constituent of biotin?

The deficiencies of micronutrients not only affect the growth of plants but also vital functions such as photosynthetic and mitochondrial electron flow. Among the list given below,which group of three elements shall affect most,both photosynthetic and mitochondrial electron transport?

Which of the following enzymes requires copper for its activity?

Which mineral element is essential for proteins,enzymes,and nucleic acids in plants?

Excess of $Mn$ in soil leads to deficiency of $Ca, Mg$ and $Fe$. Justify.

Which element is present in the structure of thiamine and biotin?