Which one of the following elements is present in the green pigment of leaves ?

The green pigment in leaves, known as chlorophyll, is a vital biomolecule essential for photosynthesis [4]. Structurally, chlorophyll consists of a light-absorbing 'head' called a porphyrin or chlorin ring and a long hydrocarbon phytol tail [1]. At the absolute center of this porphyrin ring, a magnesium ion (Mg2+) is coordinately bonded to four nitrogen atoms. This central magnesium atom is crucial for the molecule's stability and its ability to capture and transfer light energy efficiently. Magnesium deficiency in plants leads to chlorosis, a condition where leaves lose their green color and turn yellow due to impaired chlorophyll synthesis. While iron is found in hemoglobin, magnesium is the specific metallic element that defines the chlorophyll structure in plants.

Sources

1. [3] Science-Class VII . NCERT(Revised ed 2025) > Chapter 10: Life Processes in Plants > FASCINATING FACTS > p. 143
2. [4] https://www.arsdcollege.ac.in/wp-content/uploads/2020/03/Role-of-Mg.pdf
3. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 25: Agriculture > Nitrogen (N) > p. 363