The importance of the root hair in absorption of the water and mineral salts
The structure of the root hairs
The root hairs extend from the epidermis cells of the root, they are lined from inside with a thin layer of cytoplasm, and each root hair has a big vacuole that contains the salt solution.
The age of the root hair does not exceed a few days because, during the extending of the root through the soil, The epidermis cells are lost from time to time by the resistance of the soil particles, So, they are replaced by new ones continuously.
The suitability of the root hair for the absorption of the water and mineral salts
The root hair has a thin membrane that allows the penetration of the water and the salts through it, The number of the root hair is large to increase the surface area for absorption of the water and the salts from the soil.
The root hair secretes a sticky substance that helps the root to penetrate the soil particles, So the hairs draw the water forming a water membrane that facilitating the absorption process, The plasma membrane is the boundary that separates the living cell from its nonliving surroundings, The plasma membrane exhibits the selective permeability.
The cell membrane of the root hair has the selective permeability property to allow some types of the salts to pass according to the plant’s need and the energy needed for this process is obtained from the respiration process, The selective permeability is a process by which the cell membrane of the root hair allows some types of the salts to pass according to the plant’s need.
The concentration of the salt solution inside its vacuole is higher than the concentration of the salt solution in the soil to help the water to transport from the soil to the root hairs by the osmosis feature.
The osmosis feature is the transmission of the water molecules through the semi-permeable membrane from an area with a high concentration of the water to an area of low concentration of the water.
The high concentration of salt solution means that it contains a small amount of the water, so this solution has a low concentration of the water, The low concentration of the salt solution means that it contains a big amount of the water, so this solution has a high concentration of the water.
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