AIIMS 2017 Botany Xylem Structure MCQ Question

Tyloses are indeed ingrowths of xylem parenchyma cells that extend into the lumen of tracheids and vessels, primarily in the heartwood (duramen) region, effectively blocking water transport and providing protection against pathogens. Option A is incorrect because tyloses are not outgrowths of the vessels themselves; rather, they originate from parenchyma cells. Option C is misleading as it suggests a different mechanism, and option D is incorrect since tyloses serve a protective function rather than being mere swellings without purpose. Understanding tyloses is crucial for comprehending how plants manage water transport and defend against disease.