Question

I know that water moves into the root hair cells from the soil via Osmosis down the water potential gradient and then this water travels through diffusion and osmosis through the symplast pathway reaching the base of the xylem vessels. But there isn't any movement of water through the apoplast pathway. So I am thinking that the water also moves in between the cell walls of root hair cells without crossing the cell membrane and hence by diffusion and then takes up the apoplast pathway. Am I correct? Because in my book, it is mentioned that water goes in by osmosis and nothing is mentioned regarding diffusion. Someone please clarify this.

Thank you

Answer 1

Yes, Water does move between the cell walls of root hair cells through the apoplast pathway, facilitated by diffusion. While osmosis plays a crucial role in water uptake by root hair cells, diffusion also contributes to the movement of water through the apoplast pathway.

Step-by-step explanation:

In plant roots, water uptake is a complex process involving osmosis and diffusion. Osmosis, driven by the water potential gradient, is responsible for the movement of water into root hair cells from the soil. This process ensures that water moves from an area of higher water potential (soil) to an area of lower water potential (root hair cells). However, once water enters the root hair cells, it doesn't solely rely on osmosis.

Diffusion, which is the movement of substances from an area of higher concentration to an area of lower concentration, also plays a role in the transport of water. Water can move between the cell walls of adjacent root cells through the apoplast pathway. This movement is driven by the concentration gradient of water in the cell walls. As a result, water can bypass the cell membrane and travel through the apoplast, contributing to the overall water transport within the plant.

In summary, while osmosis is fundamental to water uptake by root hair cells, diffusion through the apoplast pathway is an additional mechanism for water movement between the cell walls. Both processes work in concert to ensure efficient water transport from the soil to the xylem vessels in the plant root.