Within an animal cell, the most abundant inorganic constituent of protoplasm is

Protoplasm is the living substance of a cell, comprising both organic and inorganic constituents. Among the inorganic components, water is the most abundant, typically constituting between 65% to 90% of the total protoplasm weight [2]. It serves as the primary biological solvent for various mineral ions, salts, and organic compounds like proteins and carbohydrates. While other inorganic substances such as sodium, potassium, magnesium, and phosphate ions are essential for maintaining osmotic pressure, enzymatic activities, and energy transfer (ATP), they collectively constitute only about 1% of the cell's mass. In contrast, water provides the aqueous medium necessary for all biochemical reactions and structural stability within the animal cell [2]. Therefore, water is the predominant inorganic constituent, far exceeding the concentration of mineral salts or trace elements like iron.

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1. [2] https://www.ncbi.nlm.nih.gov/books/NBK9879/