Question

The principal pathway of water translocation in angiosperms is
A. Sieve cells
B. Sieve tube elements
C. Xylem vessel system
D. Xylem and phloem

Answer 1

Hint: Translocation of water means the movement of particles such as ions, molecules from the roots to the desired parts of the plant.

Complete answer: 1. Angiosperms are seed-bearing plants that have companion cells and vessels. Water translocation is the transport of ions and molecules from soil (roots) to the desired location that occurs in xylem vessels as the result of the transpiration stream.
2. Transpiration is the evaporation of water from the leaves by mesophyll cells, also loss of water vapor through the stomata. During transpiration there produces tension or pull on the water in the xylem vessels. As water molecules are cohesive, it is pulled up through xylem vessels.
3. The transpiration stream not only helps to translocate water but also it helps in providing water to keep cells turgid, but also provides water for photosynthesis, and keeps the leaves cool by evaporation.
4. The rate of increased transpiration also increases the rate of absorption of water.

So, the correct answer is “Option C”.

Additional Information: 1. Phloem transports food from the leaves to the other parts of the plant.
2. Xylem consists of elongated dead cells, arranged in an order to form xylem vessels.
3. Mature xylem vessels have no cytoplasm.
4. Xylem and phloem are found in a group known as vascular bundles.
As xylem vessels are tough and strong, the vascular bundles are in the center of the root.
This helps to resist forces that could easily pull the plant away from the ground.
5. The leaves in hot dry climate transpire less water due to adaptation.

Note: The rate of transpiration is affected by humidity, temperature, wind speed, and light intensity.