SCIENCE
CELL BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Made up of dead cells.
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Carry water and mineral ions from the roots to the stem and leaves.
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Water can freely evaporate through the waxy walls of the xylem.
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Transport goes in one direction.
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Detailed explanation-1: -The direction of xylem transport is upwards and unidirectional i.e. from roots to other plant parts. The water column moves only upwards because of the two forces, transpirational pull, and positive root pressure.
Detailed explanation-2: -One of the main difference between xylem and phloem is that xylem can conduct substances only in one direction, whereas, phloem can transport substances in both directions.
Detailed explanation-3: -There are two main reasons due to which the xylem is unidirectional, namely positive root pressure and transpiration pull. Positive root pressure means it is against the gravitational pull, and the transpiration pull acts as a suction pump for the xylem tube. Thus, the water rises upwards.
Detailed explanation-4: -Xylem is unidirectional, whereas, phloem is bidirectional.