Question

C. CELLS THAT TRANSPORT STUFF 1. Make several cross and longitudinal sections of potato and celery stems to observe vessels and tracheids of xylem tissue, and sieve cells of the phloem. What is the function of each of these types of cells? 2. Stain the sections with Aniline Blue (stains the B-1,3 glucose polymer callose located in sieve elements) and Phloroglucinol (stains the phenolic polymer lignin in secondary walls of vessels and tracheids). Were you correct in identifying phloem and xylem? How would you describe the secondary cell wall thickenings of the vessels and tracheids? Why are they shaped this way? D. CELLS THAT PROVIDE STRUCTURAL SUPPORT 1. Make another cross section of potato and celery stems and look for collenchyma cells just under the epidermis and groups of fibers associated with vascular bundles. Are the walls of these cells thick because they are comprised of extra-thick primary walls or secondary walls?

Answer 1

Vessel elements is one of the tissues found in the xylem of plants.
It is also known as a trachea. It is found typically in angiosperms.
It is the most specialized organ and conducts water efficiently.

Tracheids are the elongated cells of vascular xylem.
They transport water as well as mineral salts.
These do not have perforation plates as seen in vessel elements.

Sieve cells are the specialized cells present in phloem tissues.
These cells originate from meristems.
These contain perforations and conduct food materials across the plant.