The correct option is (c) 2 and 3 only.
Explanation
Xylem is a complex permanent tissue in plants responsible for the conduction of water and minerals from roots to the stem and leaves. It also provides mechanical strength to the plant parts. It is composed of four different kinds of elements: tracheids, vessels, xylem fibres, and xylem parenchyma.- Statement 1 is Incorrect: Tracheids and vessels are not spherical. Tracheids are elongated or tube-like cells with thick and lignified walls and tapering ends. Vessels are long cylindrical tube-like structures made up of many cells called vessel members. Their tubular shape is essential for the vertical conduction of water.
- Statement 2 is Correct: Among the four components of xylem, xylem parenchyma is the only living component. These cells are living and thin-walled, with cell walls made of cellulose. They store food materials like starch or fat and other substances like tannins. Tracheids, vessels, and xylem fibres are dead at maturity and lack protoplasm.
- Statement 3 is Correct: Xylem fibres have highly thickened walls and obliterated central lumens. They are dead cells. Their primary function is to provide mechanical support to the plant structure.
Key Takeaway: Xylem is a complex tissue where the majority of elements (tracheids, vessels, fibres) are dead and lignified for conduction and support, while xylem parenchyma is the sole living element responsible for storage.