AP BIOLOGY

Detailed explanation-1: -Xylem conducts minerals and water only in the upward direction i.e. from the roots towards the stem. The phloem transports food material from leaves to other parts of the plant body. It can conduct food in both directions.

Detailed explanation-2: -The xylem transports water and minerals from the roots up the plant stem and into the leaves.

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.

Detailed explanation-5: -Xylem is unidirectional; its job is to make sure water flows upward. However, phloem is bidirectional and transports food and nutrients to all of the plant. Mature xylem is made up of dead cells that do not have cell contents, while phloem contains living cells (albeit without nuclei).