Question

The elements of the xylem are:
A. Tracheids
B. Vessels
C. Xylem parenchyma
D. Sclereids
Choose the correct answer from the options given below :

• A. A, B and D only
• B. A, B and C only
• C. A, B, C and D
• D. B, C and D only

Hint:

Remember the four components of xylem as "TV-XF-XP": Tracheids, Vessels, Xylem Fibres, and Xylem Parenchyma. Note that both xylem fibres and sclereids are types of sclerenchyma, but only fibres are listed as a main component of xylem.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The question asks to identify the constituent elements of xylem tissue. Xylem is a complex permanent tissue in vascular plants responsible for conducting water and minerals from the roots to the rest of the plant and providing mechanical support.
Step 2: Detailed Explanation:
Xylem is composed of four main types of cells or elements:

Tracheids (A): These are elongated, tube-like cells with tapering ends and lignified walls. They are the primary water-conducting elements in gymnosperms and pteridophytes.
Vessels (B): These are long cylindrical structures made up of many cells called vessel members, arranged end to end. They are the main water-conducting tissue in angiosperms.
Xylem Parenchyma (C): These are living parenchymatous cells associated with xylem. They are responsible for the storage of food materials and the radial conduction of water.
Xylem Fibres: These are sclerenchymatous cells that provide mechanical strength to the plant body.
Now let's look at option D:

Sclereids (D): Sclereids (or stone cells) are a type of sclerenchyma tissue. While xylem fibres are also sclerenchymatous, sclereids are not considered one of the four fundamental components of xylem tissue. Sclereids are typically found in other parts of the plant like the cortex, pith, fruit walls, and seed coats, providing hardness and support.
Therefore, the primary elements that constitute the xylem tissue are tracheids, vessels, and xylem parenchyma (along with xylem fibres). Sclereids are not a standard component.
Step 3: Final Answer:
The correct elements of xylem listed in the options are A (Tracheids), B (Vessels), and C (Xylem parenchyma). Thus, the correct choice is A, B and C only.