Question

In xylem, fibres give strength to

• A. Vessels
• B. Tracheids
• C. Parenchyma
• D. Storage tissue

Answer 1

The correct option is A Vessels

Xylem consists of tracheids, vessels, fibres and parenchyma. Tracheid is the fundamental single elongated dead cell of xylem. Tracheids show unequal cell wall thickening making the walls thick at some places and thin at others, they have a narrow cavity. Thus, due to the presence of thick rigid walls, tracheids do not need additional mechanical support but they impart mechanical strength to the parts where fibres are not supportive.
The vessel cells are arranged an end to end in a vertical fashion to make a vessel with either their cross-walls dissolve completely or having simple or complex perforation plates between successive cells to facilitate water conduction. Vessels show lesser cell wall thickening and have a greater diameter than tracheids. Due to thin cell walls, vessels need mechanical support to withstand the pressure of sap, during its ascent, which is provided by fibres. Parenchyma serves as storage tissue and does not need mechanical support.
Thus, the correct answer is option A.