Question

Assertion :Tracheids and the tracheae, the dead tissues are chief conducting tissues and their death is of great advantage to plants. Reason: In the dead tissues, the water and solutes move freely and have not to diffuse through any differentially permeable membranes, making conduction rapid and efficient.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Assertion is incorrect but Reason is correct.

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

Xylem is a water conducting tissue in plant body. Xylem is made of tracheids, vessels (tracheae), xylem parenchyma and xylem fibres. Of these four, tracheids and vessels (tracheae) are chief conducting elements in xylem.
Tracheids are hard, thick, elongated, tube-like, dead cells having tapering ends. They possess long cavity or lumen which extends throughout the tracheid.
Vessels are also called as tracheae. They are tube like, cylindrical, dead cells with lignified walls and large cavity. Due to death of tracheids and vessels, the cells possess a large cavity or lumen and form a pipe-line like structure through which solutes move freely.

Thus, the correct answer is option A.