Water and Mineral Salts are Transported by Xylem:

The xylem is a specialized vascular tissue in plants that is responsible for the transport of water and minerals from the roots to the rest of the plant. This transport system is crucial for the survival and growth of plants, as water is essential for various physiological processes and mineral salts are necessary for the synthesis of important molecules.

Water Transport:
- The primary function of xylem is to transport water from the roots to the leaves. This process is driven by transpiration, which is the loss of water vapor from the leaves through small openings called stomata.
- Water is absorbed by the roots through root hairs and is then transported upward through the xylem vessels. This transport occurs in a unidirectional manner, from the roots to the shoots.
- The movement of water in the xylem is facilitated by a combination of physical forces, including cohesion, adhesion, and tension. Cohesion refers to the attraction between water molecules, while adhesion refers to the attraction between water molecules and the walls of the xylem vessels. Tension is created when water is lost through transpiration, causing a pull on the water column in the xylem.

Mineral Salt Transport:
- In addition to water, the xylem also transports mineral salts from the roots to the rest of the plant. Mineral salts are essential for various metabolic processes, such as the synthesis of enzymes and the maintenance of osmotic balance.
- Mineral salts are absorbed by the roots through active transport, which involves the expenditure of energy. Once inside the root cells, these mineral salts are transported into the xylem vessels and subsequently distributed to the different parts of the plant.
- The transport of mineral salts in the xylem occurs passively, driven by the flow of water. As water moves upward through the xylem, it carries along dissolved mineral salts, allowing for their distribution throughout the plant.

Organic Nitrogen and Hormones are not Transported by Xylem:
- While the xylem is responsible for the transport of water and mineral salts, it does not transport organic nitrogen and hormones. These substances are primarily transported by another vascular tissue called the phloem.
- The phloem is responsible for the transport of organic molecules, such as sugars (including sucrose), amino acids, and hormones, from the leaves to the rest of the plant. This transport occurs in a bidirectional manner, allowing for the distribution of these substances to areas of need.
- The movement of organic molecules in the phloem is facilitated by pressure flow, which involves the accumulation of solutes in source regions (such as leaves) and their subsequent movement to sink regions (such as roots or developing fruits).

In summary, the xylem transports water and mineral salts from the roots to the rest of the plant, while organic nitrogen and hormones are primarily transported by the phloem. This division of labor between the xylem and phloem allows for the efficient distribution of essential substances throughout the plant.

Xylem do not transport the sugars.