Phloem and Principal Water-conducting Elements

Exercise 4 (Histology) 1. 1 Give at least three distinguishing features of these groups of cells. Apical meristems have the following features: (1) a “border” of cells; (2) they follow order or shape; and (3) some cells are darker (indicating that they undergo mitosis). 2. 1 Identify the tissue. The tissue is a vascular cambium. 4. 5 (? ) Is the epidermis uniseriate or multiseriate? In the cross section of a young root of Helianthus, the epidermis is uniseriate. 6. 1 What do you call the outgrowths of the epidermis? These are called trichomes. 6. 2 What is their function?
They function mainly for support and protection of the leaf or stem which contains the epidermis. 6. 3 Classify the types of epidermal outgrowths in the above plants. bristle| scale| simple hair| glandular| branching| stellate| 7. 1 Draw and identify the tracheary elements. reticulate| annular| pitted| scalariform| helical| 8. 1 Differentiate the sieve tubes from the companion cells. The sieve tubes in the phloem are composed of long, narrow cells which lack a nucleus, ribosomes, and some other cellular components; they transport sugars and other organic nutrients.
Companion cells have nuclei and ribosomes that also serve the sieve-tube cells but do not themselves take part in conduction. 8. 2 What are the principal water-conducting elements of the xylem? The two principal water-conducting elements of the xylem are the tracheids and the vessel elements. 9. (Table 4. 1) Specimen| Tissue| Cell Types| Characteristic(s)| Function(s)| Cassava pith| | | | | Tomato fruit pulp| | | | | Spanish flag petiole| | | | | Lotus peduncle| | | | | Celery petiole| | | | | Coleus petiole| | | | | Mung bean seed coat| | | | | Peanut pericarp| | | | | Pineapple leaf| | | | | Others| | | | |