A) vessels
B) companion cells
C) tylosoides
D) albuminous cells
E) secretory cells
Correct Answer: B
Solution :
Companion cells are thin walled, elongated cells connected with sieve tube cells through plasmodesmata, in phloem cells. They are the characteristic of angiosperms, functions in controlling metabolic activities of sieve tube cells by nucleus of companion cells. Companion cells are absent in gymnosperm and pteridophytes. In conifers, albuminous cells are present in place of companion cells of phloem tissue. Vessels are cells of water conducting xylen tissue. They are present only in angiosperm, and Gnetales in gymnospenns. Tyiosoids or thylosoids are the structures resembling tyiosis, which is parenchymatous intrusion into a resin duct, sieve tube or any canal other than vessel. Common in gymnosperms. Secretory cells are specialized individual cells present here and there producing oil (oil cells, eg. Citrus, sunflower), tannin (tannin cells eg, Caccia) resin (resiniferous cells, eg, Pinus), mucilage (mucilagenous cells eg, Cactaceae) and crystals. They can be seen both in gymnosperms and angiosperms.
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