Atlas of Plant and Animal Histology

Choose true or false. Each right answer scores 1, and each wrong answer scores -1. Not answered questions score 0.

1) Tracheids have been shortened during evolution. They are only found in gymnosperms.

2) Annular and reticular thickenings of the cell wall of tracheae are features of the protoxylem.

3) Water travels via symplast through the lateral areolate pits of tracheae, but mostly travels through the perforated plates of the transverse cell walls.

4) The main force propelling water along the xylem is the root water pressure.

5) The mature conducting elements of the xylem are cells with thick cell walls and without cytoplasm.

6) The sieve elements loose their nucleus during differentiation.

7) Sieve elements communicate between each other only by pit fields know as sieve plates.

8) The main role of albuminiferous and associated cells is to provide physical support to the phloem tissue.

9) Sieve cells are the only conducting element in the phloem of gymnosperms.

10) During secondary growth, protophloem and protoxylem are replaced by secondary phloem and secondary xylem.

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F-1) Asterisks indicate the metaxylem tracheae.

F-2) Labels are correctly placed.