THE CELL WALL Before traversing the plasma membrane(p. m), ions must first cross bulk flow of soil solution couls the cell wall and contact the p The theoretically carry inorganic ions into the cell wall and through the apoplastic athway. the thickness of a cell wall is in the range of 500 to 1000 nm it is orousTHE CELL WALL • Before traversing the plasma membrane (p.m.), ions must first cross the cell wall and contact the p.m. The bulk flow of soil solution could theoretically carry inorganic ions into the cell wall and through the apoplastic pathway. The thickness of a cell wall is in the range of 500 to 1000 nm. It is porous