Question

Which of the following is not a criterion for essentiality of an element ?

• A. Requirement of the element is specific
• B. Necessary for normal growth and reproduction
• C. Not replaceable by another element
• D. Indirectly involved in plant metabolism

Answer 1

The Correct Option is D

Arnon and Stout $(1939)$ proposed criteria for knowing the essentiality of an element. These are : (i) It is indispensable for the growth of plants. (ii) The element is directly involved in the metabolism of plants. (iii) A plant is unable to complete its vegetative or reproductive phase in the absence of the element. (iv) The element cannot be replaced by any other element. (v) The absence or deficiency of the element produces disorders. These disorders are a direct result of the lack or deficiency of the element. (vi) The element alone can correct the disorders produced by its absence or deficiency. Hence, it is clear that an element indirectly involved in plant metabolism does not fit into criterion for essentiality of an element.