Which of the following elements is most mobile in plant metabolism?
A. Calcium
B. Phosphorus
C. Carbon
D. Magnesium

Hint: Plant metabolism is defined as the complex of physical and chemical events of photosynthesis, respiration, and the synthesis and degradation of organic compounds. Plants and all living things, need nutrients and minerals to exist. Chemical elements are needed for growth, metabolic functioning, and completion of its life cycle.

Complete answer:

Option- A - Calcium- Calcium is an important plant nutrient. It is needed for structural roles in the cell wall and membranes, as a counter‐cation for inorganic and organic anions in the vacuole, and as an intracellular messenger in the cytosol.

Option-B- Phosphorus- Phosphorous can be called as relatively mobile as it is immobile when present in nucleic acids. But other than nucleic acids phosphorus is mobile and participates in reversible phosphorylation reactions of ADP to generate ATP.

Option-C- Carbon- Carbon is a framework mineral which is tightly bound through covalent bonds in biomolecules and forms the basic framework of the plant body. plants take in carbon dioxide which is then converted to energy for growth carbon in plants ensure to foster healthier and more productive growth of the plants.

Option-D-Magnesium- Magnesium is the central core of the chlorophyll molecule that is present in plant tissue.If there is deficient of Mg,the shortage of chlorophyll will result in poor and stunted plant growth. Magnesium even helps in activating specific enzyme systems in the plants.

So, the right answer to this question is option B “Phosphorus”.

Note:
Phosphorus is the most mobile element in terms of plant metabolism and even participates in reversible phosphorylation reactions of ADP to generate ATP. Phosphorus is an essential macronutrient for plants that is used in plant metabolism.