Introduction

Plants need water to complete their lifecycle. They absorb water from the soil through their roots, and this water travels throughout the plant to reach all its parts. But how does the water move up through the plant, against the force of gravity?

The role of xylem

The xylem is a specialized tissue in plants that transports water from the roots to the leaves. It consists of elongated cells that form long, hollow tubes connected end-to-end. Xylem cells are dead at maturity and have thick, lignified cell walls that provide structural support to the plant.

Water uptake by roots

Plant roots absorb water from the soil through tiny, hair-like structures called root hairs. Water molecules move from the soil into the root hairs by osmosis. Osmosis is a process that involves the movement of water molecules from an area of high concentration to an area of low concentration, across a selectively permeable membrane.

Water transport in xylem

Once water enters the root hairs, it moves through the root cortex and enters the xylem. The water molecules move from one xylem cell to another through tiny pores called pits. The pits allow water to move from one cell to another while maintaining structural support.

Role of cohesion-tension theory

The cohesion-tension theory explains how water is transported through the xylem from the roots to the leaves. According to this theory, water molecules are polar and are attracted to each other by hydrogen bonds. This cohesive force creates a continuous column of water in the xylem.

Transpiration pull

Transpiration is the process by which water is lost from the leaves of a plant through tiny pores called stomata. As water evaporates from the leaves, it creates a negative pressure or tension in the xylem, which pulls more water up from the roots through the cohesion-tension theory.

Conclusion

In summary, xylem is a specialized tissue that transports water from the roots to the leaves of a plant. The transport of water in xylem is driven by the cohesion-tension theory and the negative pressure created by transpiration. Understanding the mechanism of water transport in plants is essential for their survival and productivity.