Question

The deficiencies of micronutrients, not only affects the growth of plants but also vital functions such as photosynthetic and mitochondrial electron flow. Among the list is given below, which group of three elements shall affect most, both photosynthetic and mitochondrial electron transport.
A. Cu, Mn, Fe
B. Co, Ni, Mo
C. Mn, Co, Ca
D. Ca, K, Na

Answer 1

Hint:- : Some elements in plants are absolutely necessary for supporting normal growth and reproduction and thus those elements are known as essential elements. The deficiency of any essential element cannot be met by supplying some other elements as they are directly involved in the metabolism of the plant.

Complete step-by-step solution:-
- The elements that are needed in very small amounts, i.e., (less than 10 m mole /Kg of dry matter) are called micronutrients or trace elements. Examples of micronutrients are iron, manganese, copper, molybdenum, zinc, boron, chlorine, and nickel. The role and deficiency of some micronutrients are discussed below:
- Calcium: Calcium is used in the synthesis of the cell wall during cell division, particularly as calcium pectate in the middle lamella. The formation of mitotic spindles is also enhanced by Ca.
- Potassium: Potassium helps to maintain the turgidity of cells and also regulates an anion-cation balance in cells. Protein synthesis, opening, and closing of stomata, activation of enzymes are important functions of potassium.
- Molybdenum: Several enzymes participating in nitrogen metabolism including nitrogenase and nitrate reductase are having an important component as molybdenum.
- Copper: Copper is a component of enzymes of redox reactions of electron oxidative phosphorylation and photophosphorylation.
- Manganese: Manganese has a vital role in activating enzymes involved in photosynthesis, respiration, and nitrogen metabolism and some enzymes of the Krebs cycle. Manganese plays an essential role in the splitting of water to liberate oxygen during photosynthesis.
- Iron: The transfer of electrons like ferredoxin and cytochromes is facilitated by iron and it further activates catalase enzyme and is essential for the formation of chlorophyll.
Thus, Cu, Mn, and Fe are mostly important in photosynthetic and mitochondrial electron transport. Hence, the correct answer is option A, Cu, Mn, Fe.

Note:- The critical concentration is the minimum concentration of the essential element below which plant growth retarded. Whenever a deficiency of any of these essential elements causes symptoms called deficiency symptoms such as chlorosis, necrosis, stunted growth, and impaired cell division.