question_answer 1)

All elements that are present in a plant need not be essential to its survival'. Comment. 

Answer:

All elements that are present in a plant need not be essential to its survival because they do not directly involved in the composition of their body. However, if the concentration of micronutrients such as Fe, Mn, Cu, Zn, Cl, etc., rise above their critical values, they appear to be toxic for the plant.