MOVEMENT OF WATER THROUGH THE ROOT
- Water initially diffuses into the root hair cells by osmosis from the soil which has a higher water potential than the cytoplasm and vacuole of the root hair cells. This is because their vacuole's and cytoplasm's contain a concentrated solution of organic and inorganic ions, decreasing the water potential and drawing water in.
- The root hair cells also provide a larger surface area for the diffusion of water into the cell.
- The water that has been taken up by the root travels across the cortex of the root either via the apoplast or symplast pathway.
- The root hair cells will always have a higher water potential than the adjacent cells, and so water will diffuse from cell to cell by osmosis, down the water potential gradient.
- The vascular tissue at the centre of the root is surrounded by a region called the pericycle, which in turn is surrounded by a layer called the endodermis. These cells have cell walls made of suberin, forming the Casparian *****, which is waterproof.
- This prevents the movement of water in the apoplast pathway, so water is forced into the cytoplasm.
- From the cytoplasm of the endodermal cells, the water diffuses into the…