How it could be apoplast as the ions have entered in the cell through ion channels via plasma membrane

Movement of ions through ion channels: Apoplast or Symplast?

Introduction:
The movement of ions through ion channels is a crucial process in plants for various physiological functions, including nutrient uptake and signal transduction. It occurs through two pathways: the apoplast and the symplast. The apoplast refers to the extracellular space outside the plasma membrane, while the symplast refers to the interconnected cytoplasmic continuum inside the cells.

Apoplast:
The apoplast pathway involves the movement of ions through the cell walls and intercellular spaces without crossing any plasma membrane. This pathway is mainly responsible for the bulk flow of water and solutes in plants. In the apoplast pathway, ions can move freely, driven by concentration gradients or pressure differences. They can easily diffuse through the cell walls and move along the apoplastic continuum.

Symplast:
The symplast pathway, on the other hand, involves the movement of ions through the cytoplasm, crossing plasma membranes of the cells. This pathway requires the ions to pass through the cell membrane via specialized transport proteins, such as ion channels or transporters. These ion channels are selective and regulate the movement of specific ions.

Ion Channels:
Ion channels are proteins embedded in the plasma membrane that allow the selective movement of ions across the membrane. They act as gatekeepers, controlling the flow of ions in and out of the cell. Ion channels are classified into various types based on their selectivity and gating mechanisms. For example, voltage-gated channels open or close in response to changes in membrane potential, while ligand-gated channels open or close in response to specific ligands binding to them.

Movement of ions through ion channels:
The movement of ions through ion channels primarily occurs via the symplast pathway. When ions are transported across the plasma membrane, they can enter or exit the cytoplasm through specific ion channels. These channels facilitate the movement of ions by creating a pore or channel that allows ions to pass through. The ions move from areas of high concentration to low concentration, driven by concentration gradients or electrochemical gradients.

Conclusion:
In conclusion, the movement of ions through ion channels primarily occurs via the symplast pathway. Although the apoplast pathway facilitates the bulk flow of water and solutes, the specific movement of ions through ion channels requires the symplast pathway. Therefore, the statement in NCERT page 200, Chapter Mineral Nutrition, that ions move through ion channels via the apoplast is incorrect.