Question

The micronutrients
A. Are less important in nutrition than macronutrients
B. Are as important in nutrition as macronutrients
C. Be omitted from culture media without any detrimental effects on the plants.
D. Called as a macro because they play only a minor role in plant nutrition

Answer 1

Hint: Nutrients that are required for plants to complete their life cycle are considered as essential nutrients. Whereas, nutrients that enhance the growth of plants but are not necessary to complete the plant's life cycle are considered non-essential nutrients. Seventeen elements or nutrients are essential for plant growth and reproduction. They are carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, iron, boron, manganese, copper, zinc, molybdenum, nickel and chlorine.

Complete step by step answer: The micronutrients are essential for plants. In their order of importance, macronutrients include iron, manganese, zinc, copper, boron, chlorine and molybdenum. Though, these nutrients are required in very small amounts but are very essential to plant health. Most of these nutrients are required in enzymatic reactions that are involved in plant metabolism. They are generally available in the mineral component of the soil, but the heavy application of phosphates can cause a deficiency in zinc and iron by the formation of insoluble zinc and iron phosphates. Iron deficiency, stemming from plant chlorosis and rhizosphere acidification, may also result from excessive amounts of heavy metals or calcium minerals (lime) in the soil. Excessive amounts of soluble boron, molybdenum and chloride are toxic.
Hence, the correct answer is option B.

Note: The nutrients adsorbed onto the surfaces of clay colloids and soil organic matter provide a more accessible reservoir of many plant nutrients (e.g. K, Ca, Mg, P, Zn). As plants absorb the nutrients from the soil water, the soluble pool is replenished from the surface-bound pool. The decomposition of organic matter present in the soil by microorganisms is another mechanism whereby the soluble pool of nutrients is replenished – this is important for the supply of plant-available N, S, P, and B from the soil.