Question

Which of the following is a micro-nutrient?
(a)Copper
(b)Phosphorus
(c)Magnesium
(d)Calcium

Answer 1

This element activates some enzymes in plants which are involved in lignin synthesis, it is essential in several enzyme systems, and helps in the process of photosynthesis. This element is also essential for plant respiration and assists in plant metabolism of carbohydrates and proteins

Complete answer:
The plants require sixteen nutrients which are absorbed by the plants and they are classified as macronutrients and micronutrients. The nutrients that are absorbed in the large quantity are macronutrients like hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, carbon, and sulfur. There are 7 essential plant nutrient elements defined as micronutrients and they are the nutrients required in a small amount like boron (B), zinc (Zn), manganese (Mn), iron (Fe), copper (Cu), molybdenum (Mo), and chlorine (Cl). They all constitute less than 1% of the dry weight of most plants. They help plants to produce enzymes, hormones, and other substances essential for proper growth and development.
Comparatively iron in the tissue is 20 times higher than that of copper. Copper helps to intensify flavor, color in vegetables, and color in flowers. Copper deficiency symptoms occur in the newer leaves. Symptoms vary depending on the plant and it might start as cupping and slight chlorosis between the veins of the new leaves or the whole leaf or browning of leaf tips. Small necrotic spots may form on the chlorosis area, especially on the leaf margins. If it continues the newest leaves are smaller in size then they are supposed to be also they will lose their sheen and in some cases, the leaves may wilt. It will stop the growth of lateral branches and the apical meristems may become necrotic and die. If other elements like potassium, phosphorus, or other micronutrients are in excess then it can indirectly cause copper deficiency.
So, the correct answer is 'Copper'.

Note: In plants the meristem is a type of tissue and is capable of continually dividing, allowing the plant to grow. There are three primary meristems: the protoderm, the ground meristem, and the procambium. Apical meristem is meristems in root and shoots tips of plants that are capable of division and give rise to the primary plant body. They are responsible for the extension of the roots and shoots.