Plant Anatomy

Choose the Correct Answer

Correct Answer : Option b

Explanation
Xylem transports water and mineral salts from the roots up to other parts of the plant. Mature xylem consists of elongated dead cells, arranged end to end to form continuous vessels (tubes). Mature xylem vessels: contain no cytoplasm; are impermeable to water; have tough walls containing a woody material called lignin.
Phloem transports sucrose and amino acids from the leaves and other parts of the plant. Phloem consists of living cells arranged end to end. Unlike xylem, phloem vessels contain cytoplasm, and this goes through the holes in the sieve plates from one cell to the next. Phloem transports sucrose and amino acids up and down the plant. This is called translocation. In general, this happens between where these substances are made (the sources) and where they are used or stored (the sinks). This means, for example, that sucrose is transported: from sources in the root to sinks in the leaves in spring time; from sources in the leaves to sinks in the root in the summer. Applied chemicals, such as pesticides, also move through the plant by translocation.