Which of the following is not a macronutrient ? A. C B. P C. N D. Zn
Hint: Macronutrients are the nutrients which are required in large quantities by plants for their growth while micro-nutrients are those which are required in lesser quantities. Plant takes these nutrients through soil. Micro and Macro nutrients both are essential nutrients or elements for plants.
Complete answer:- Macro-nutrients are required in relatively large quantities like one to 10 milligram per gram of dry matter. Examples: Carbon, Hydrogen, Oxygen, Phosphorous, Potassium, Calcium, Magnesium, Nitrogen and Sulphur. Here, Carbon, phosphorus and nitrogen are macronutrients which play an important role in plant growth and development. Micronutrients are required in minute quantities like 0.1 mg per gram of dry matter or less than that. Also called as trace elements. Examples: Manganese, Boron, Cobalt, Copper, Molybdenum, Iron, Zinc and Chlorine are required in very small quantities. Here, Zinc is an essential micronutrient. It is required as an essential element for activity of a number of enzymes like alcohol dehydrogenase, carbonic anhydrase etc.
Thus, the correct answer is option D.
Note:- Both macro and micro nutrients are equally important for plant growth and development but they are divided according to the amount that plant requires. Nitrogen, phosphorus and potassium are the primary macronutrients. Essential elements perform various functions. They carry out several metabolic processes in the plant cells like the maintenance of turgidity of cells, transportation of electrons, membrane permeability and enzyme activity. Essential elements also act as important constituents of the biomolecules and co-enzymes.