Question

Select the incorrect statement from the following: (a) Vessel members are interconnected through perforations in their common walls. (b) Presence of vessel is a characteristic feature of angiosperms. (c) Radial conduction of water takes place by the ray parenchymatous cells. (d) Tracheids, vessel, xylem sclerenchyma and parenchyma are without protoplast.

Short answer

The incorrect statement is (d) Tracheids, vessel, xylem sclerenchyma and parenchyma are without protoplast. This is because while tracheids, vessels, and xylem sclerenchyma are dead at maturity and lack protoplast, xylem parenchyma cells are alive and contain protoplast.

Step-by-step solution

Understanding Vessel Members

Vessel members are a type of cell found in xylem, the water-conducting tissue of plants. They are connected end-to-end, which allows them to form long conducting tubes. The walls between adjacent vessel members possess perforations, which allow water to flow freely between the vessels. Therefore, statement (a) is correct.

Presence Of Vessels in Angiosperms

Vessels are a defining characteristic of angiosperms, or flowering plants. They provide efficient water transportation, allowing these plants to grow taller and faster. Therefore, statement (b) is correct.

Role of Ray Parenchymatous Cells

Ray parenchymatous cells are a type of cell in the xylem and phloem of vascular plants. They are responsible for the radial conduction of water and nutrients. Therefore, statement (c) is correct.

Composition of Tracheids, Vessels, Xylem Sclerenchyma, and Parenchyma

Tracheids, vessels, and xylem sclerenchyma are all components of the xylem and are dead at maturity, meaning they lack protoplast, or cellular material. However, the parenchyma cells in the xylem are alive and contain protoplast. Therefore, statement (d) is incorrect.

Key concepts

Vessel Members

Vessel members play a crucial role in the structure and function of the xylem, which is the tissue responsible for transporting water and nutrients in plants. Unlike other xylem components, vessel members are uniquely structured to maximize efficiency in water conduction. These are elongated, tube-like cells that are joined end-to-end, forming long continuous columns.

One special feature of vessel members is the presence of perforations in their end walls. These perforations allow water to move seamlessly from one vessel member to another, essentially acting like tiny tunnels connecting the vessels. This design reduces resistance and facilitates a faster and more efficient flow of water, catering well to the needs of plants that require rapid water transport.

In summary, vessel members are vital for the effective operation of xylem and contribute significantly to a plant's ability to grow and transport necessary substances.

Ray Parenchyma

Ray parenchyma is a type of cell found within the xylem and is pivotal for the radial conduction of water and nutrients. These cells are arranged in radial patterns, extending from the center of the stem outwards towards the periphery.

The main role of ray parenchyma is to transport water and nutrients across the xylem, which helps in distributing these vital substances throughout different parts of the plant. This ability to conduct water radially is crucial for the plant’s overall nutrient distribution.

Additionally, ray parenchyma cells are living cells, which means they maintain cellular processes actively. This is an essential factor as it also aids in the storage of different materials like starch and other substances that are important for the plant’s growth and survival.

Thus, the presence of ray parenchyma aids in both the lateral movement of nutrients and storage within the plant anatomy.

Angiosperms

Angiosperms, commonly known as flowering plants, are a diverse and wide-ranging group of plants characterized by the presence of flowers and seeds enclosed within a fruit. This group represents the dominant form of plant life in most terrestrial ecosystems.

One of the key features of angiosperms is their highly efficient vascular system, wherein vessels are significant components. Vessels facilitate a more rapid transport of water and nutrients compared to the tracheids, which are the main conducting elements in gymnosperms (non-flowering seed plants). This efficiency allows angiosperms to grow larger, spread faster, and adapt more effectively to diverse environments.

This advanced trait of having vessels contributes to the success of angiosperms, thus making them the most varied and ecologically significant group of the plant kingdom.

Tracheids

Tracheids are another essential component of the xylem, fundamental to the conduction of water and support within plants. These cells are more primitive compared to vessel members and exist in both gymnosperms and angiosperms.

Structurally, tracheids are long, tapered cells that overlap one another. Water moves through these cells via pits, which are small openings that allow water to flow from one tracheid to the next. Unlike vessels, tracheids do not have perforated end walls, which means the process of water movement is slower. Yet, this structure makes them more resistant to blockages and damage.

Although tracheids are not as efficient as vessel members in transporting water, their role is still vital, especially in gymnosperms and other less advanced vascular plants. Tracheids also contribute to the structural support of the plant, providing firm support against various environmental stresses.