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QUESTION 1
1. List the cell types concerned with transport of water in angiosperms, and briefly explain the
differences between these cell types.
Water Transport in Angiosperms
In angiosperms, the transport of water is primarily carried out by specialized cells known as
tracheary elements, which include tracheids and vessel members. These cells are essential
components of the xylem, the vascular tissue responsible for conducting water and minerals from the
roots to the rest of the plant.
Tracheids and Vessel Members
Tracheids and vessel members both function as water-conducting cells but exhibit key structural and
functional differences. Tracheids are elongated cells with tapered ends and are interconnected
through pits, allowing water to pass between them. They provide both conduction and structural
support to the plant.
Vessel members, on the other hand, are shorter and wider cells that align end-to-end to form
continuous tubes known as vessels. These vessels enable more efficient water transport due to their
larger diameter and the presence of perforation plates at their ends, which allow for rapid movement
of water with minimal resistance.
Differences Between Tracheids and Vessel Members
While both tracheids and vessel members share common features such as the presence of pits and
lignified cell walls, they differ in their connectivity and efficiency. Tracheids rely on pit membranes
for water movement, making transport slower compared to vessels, which allow for direct and faster
water flow through perforations. Additionally, plasmodesmata, which facilitate communication
between living cells, are present in immature tracheary elements before they mature and become
hollow conduits for water conduction.
Overall, both cell types contribute to the efficient movement of water in angiosperms, with vessel
members playing a more dominant role in rapid water conduction, while tracheids provide additional
support and safety against air embolisms.