The water and minerals absorbed by the roots of a plant move upwards to the other parts of the plant through the xylem. Here is a detailed explanation of this process:
Xylem:
- The xylem is a specialized tissue in plants that is responsible for the transport of water, minerals, and nutrients from the roots to the other parts of the plant.
- It is composed of long, hollow, and tube-like cells called tracheary elements, which are dead at maturity.
- The tracheary elements include two types of cells: the vessel elements and the tracheids.
- Vessel elements are found in angiosperms (flowering plants) and are arranged end to end to form long tubes.
- Tracheids are found in gymnosperms (non-flowering plants) and are more primitive in structure compared to vessel elements.
Process of Water and Mineral Transport:
- Water and minerals are absorbed by the roots through root hairs, which are located on the surface of the root.
- These substances enter the root cells through osmosis and active transport.
- Once inside the root cells, water and minerals are transported across the root cortex towards the xylem.
- The movement of water and minerals from cell to cell within the root is facilitated by specialized structures called plasmodesmata.
- Once in the xylem, water and minerals are transported upwards through the plant, primarily through the process of transpiration.
Transpiration:
- Transpiration is the loss of water vapor from the aerial parts of the plant, mainly through the stomata present on the leaves.
- As water evaporates from the leaf surface, it creates a negative pressure or tension within the xylem.
- This negative pressure pulls water from the roots, creating a continuous flow of water and minerals upwards through the xylem.
- This process is known as the cohesion-tension theory.
- The movement of water and minerals through the xylem is unidirectional and occurs from the roots to the shoots.
In conclusion, the solution of water and minerals absorbed by the roots moves upwards to the other parts of the plant through the xylem. This transport is facilitated by the process of transpiration and the cohesion-tension theory.