Questions & Answers

In angiosperms, xylem is made up of
A) Tracheids and vessels
B) Vessels and fibres
C) Tracheids and fibres
D) All the above

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Hint: Xylem is one of the transportation systems of plants which is used by the plants to transport water to all the parts of the plant so that they can perform the necessary functions.

Complete answer:
Xylem transports the water from the roots of the plant to the other parts. Along with water it also transports nutrients from roots to stems to other plant parts. The xylems structure consists of lignified tracheary elements like tracheids and vessel elements which are dead at maturity.

Both tracheary elements are long hollow cells with tapered end walls. The end walls of adjacent tracheids contain paired small, rimmed, nonperforated pores which are called bordered pits. It helps in water diffusion. Parenchyma cells also are interspersed throughout the tissue. Along with parenchyma cells fibres are also present in the xylem of angiosperms.

Vessel elements of the angiosperm xylem system differ from tracheids as the end walls are modified into perforation plates. Vessel elements join to form continuous vessels. The perforations are much larger than those of the bordered pits of tracheids and are of four types: scalariform , foraminate which are circular, reticulate , or simple. Since xylem in angiosperms have all tracheids, vessels and fibres, thus option D is the incorrect answer.

Hence the correct answer is option (D) All the above.

Note: The most common type of perforation plates in the angiosperms are scalariform and simple which aids the xylem to carry out their function.