Question

Which of the following statements is true?
A. Vessels are unicellular and with narrow lumen
B. Vessels are multicellular and with wide lumen
C. Tracheids are unicellular and with wide lumen
D. Tracheids are multicellular with narrow lumen

Answer 1

Vessel, in botany, the most specific and productive leading structure of xylem (liquid directing tissues). Normal for most blossoming plants and missing from most gymnosperms and greeneries, vessels are thought to have advanced from tracheids (a crude type of water-directing cell) by loss of the end dividers.

Complete answer:
• A vessel comprises a vertical arrangement of vessel individuals that differ from lengthened to crouch, molded cells the dividers of which are optionally thickened with rings, twistings, or organizations of cellulose, that later become lignified.
• The length of vessels fluctuates from two cells to lines a few meters in length.
• During improvement, the end dividers, effectively hollowed, get through and inevitably vanish.
• The living protoplast of the cell likewise separates and vanishes.
• The presence of vessels in xylem has been viewed as one of the key advancements that prompted the achievement of the blooming plants.
• It was once imagined that vessel components were a developmental advancement of blooming plants, however their nonattendance from some basal angiosperms and their quality in certain individuals from the Gnetales propose that this theory must be rethought.

Hence, the correct answer is option (B).

Note: Vessel components in Gnetales may not be homologous with those of angiosperms, or vessel components that began in a forerunner to the angiosperms may have been consequently lost in some basal genealogies (e.g., Amborellaceae, Tetracentraceae, Trochodendraceae, and Winteraceae), portrayed by Arthur Cronquist as "crudely vesselless". Cronquist believed the vessels of Gnetum to be united with those of angiosperms.