explain how water is transport from the root to mesophyll cells in a leaf
The transportation of water from the roots to the mesophyll cells in a leaf involves a process known as the transpiration-cohesion-tension mechanism. Here's a step-by-step explanation:
1. Water absorption: Water is absorbed by the root hairs in the root system of a plant. These root hairs increase the surface area of the roots, allowing for more efficient water absorption.
2. Capillary action: Once water is absorbed by the roots, it moves up the plant through tiny channels called xylem vessels. Capillary action, which is the result of adhesive and cohesive forces, allows water to move upwards against gravity.
3. Transpiration: As water molecules are transported upwards through the xylem, some of them evaporate from the stomata in the leaves. Stomata are small openings on the underside of leaves that regulate the exchange of gases and water vapor.
4. Cohesion and tension: The evaporation of water through the stomata creates a partial vacuum, or negative pressure, within the leaf. This leads to a phenomenon known as "transpiration pull." Water molecules, due to their cohesive properties, stick together and form a continuous column within the xylem vessels. As water is lost through transpiration at the top of the plant, the cohesive forces pull more water molecules up from the roots.
5. Adhesion: Water molecules also adhere to the inner walls of the xylem vessels. Adhesive forces between water molecules and the xylem cells help counteract the gravitational pull and provide additional support for water transport.
6. Movement into mesophyll cells: Eventually, water reaches the mesophyll cells in the leaf. These are the cells responsible for photosynthesis. Water is then used as a raw material in the process of photosynthesis, supporting the creation of glucose and other organic molecules.
In summary, water is transported from the root to the mesophyll cells in a leaf through a combination of capillary action, transpiration, cohesion, tension, and adhesion.