Which of the following is a dead tissue? (a) Sieve tube (b) Companion cells (c) Parenchyma (d) Fibres

Vascular tissues are the complex conducting tissues in plants responsible for transporting water, minerals, and food throughout the plant. There are two main types of vascular tissues: xylem and phloem. The xylem transports water and dissolved minerals from the roots upwards to all parts of the plant. It is made up mostly of dead cells that form a continuous tube-like structure, allowing for efficient water movement.

On the other hand, the phloem moves nutrients, particularly sugars produced by photosynthesis in the leaves, to different parts of the plant, including growing tissues and storage organs. Unlike the xylem, the phloem is comprised mostly of living cells. The efficient movement of these substances is crucial for the plant's survival, growth, and development.

Phloem cells are one of the key components in plant vascular tissues. Understanding their characteristics provides insight into how they function within the plant. Primarily, phloem cells facilitate the transport of nutrients, especially sucrose, to various parts of the plant. These cells are not only effective in long-distance transport, but they also play an essential role in communication across the plant.

The main types of cells in the phloem are sieve elements, companion cells, phloem fibres and phloem parenchyma. Sieve elements, including sieve tubes and sieve cells, are responsible for the actual transport. Companion cells assist sieve elements in their function, and the close association between them is crucial for the transportation and distribution of nutrients. Phloem fibres contribute to the support and structural integrity, while phloem parenchyma cells serve roles in storage and lateral transport.

The structure of plant cells is distinctive due to certain features that cater to their specific functions. All plant cells are surrounded by a rigid cell wall made of cellulose, providing strength and support to the plant's structure. Unlike animal cells, plant cells also contain chloroplasts, the organelle where photosynthesis occurs, converting light energy into chemical energy.

Inside the cell, the large central vacuole plays a role in maintaining cell pressure, storage, and waste disposal. The presence of a cell membrane just inside the cell wall helps control the movement of substances in and out of the cell, ensuring only the necessary nutrients and ions are absorbed. These cells work collectively within various tissues of the plant to perform essential functions like growth, nutrient transport, and energy production, forming the basis of plant life.