plant anatomy Questions

In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to:(a) Secretion of secondary metabolites and their deposition in the lumen of vessels.(b) Deposition of organic compounds like tannins and resins in the central layers of the stem.(c) Deposition of suberin and aromatic substances in the outer layer of the stem.(d) Deposition of tannins, gum, resin and aromatic substances in the peripheral layers of the stem.(e) Presence of parenchyma cells, functionally active xylem elements and essential oils.Choose the correct answer from the options given below:

Read the following statements about the vascular bundles:(a) In roots, xylem and phloem in a vascular bundle are arranged in an alternate manner along the different radii.(b) Conjoint closed vascular bundles do not possess cambium.(c) In open vascular bundles, cambium is present in between xylem and phloem.(d) The vascular bundles of dicotyledonous stem possess endarch protoxylem.(e) In monocotyledonous root, usually there are more than six xylem bundles present.Choose the correct answer from the options given below:

The anatomy of springwood shows some peculiar features. Identify the correct set of statements about springwood:(a) It is also called early wood(b) In the spring season cambium produces xylem elements with narrow vessels(c) It is lighter in colour(d) The springwood along with autumnwood shows alternate concentric rings forming annual rings(e) It has lower densityChoose the correct answer from the options given below: