Anatomy of Flowering Plants Test - 88

Latex is a milky white secretory material. It is secreted by a special tissue  called are Laticiferous tissues. These are found in the plants growing in tropical deciduous forests. These are present in two types, namely latex cells and latex vessels. Latex is used in the manufacture of rubber. In the plants

The large sized, slightly raised spots present on the surface of cork, in old dicot stems are called Lenticels. These are involved in the exchange of gases.

The small pores, present on the epidermis of grass leaves are called Hydathodes. In this guard cells are immovable. They perform guttation.

So, the correct option is ‘There is no regulation of their opening and closing’.

A. In dicot root, the vascular bundles are collateral and endarch - False, because, in dicot root radial vascular bundles are present.

In monocot stem vascular bundles are oval shaped, scatteredly arranged in the ground tissue. The stele is called Atactostele. Each vascular bundle is outerly surrounded by sclerenchymatous fibres. So they are called Fibrovascular bundles. In this, xylem and phloem are present on same radii, and also present side by side. So they are also called Collateral and Conjoint vascular bundles. In the vascular bundles, cambium is absent between xylem and phloem, So these are closed vascular bundles. In the xylem, protoxylem is towards the centre, and metaxylem is towards the periphery. So, it is an endarch xylem. In the protoxylem, some of the cells, disintegrate, and form into a lysigenous cavity, called as Protoxylem lacuna.

A.Monocot root - many radial vascular bundles are present.

In dicotyledonous stems of temperate trees, during secondary growth, vascular cambial ring(narrow layer of thin-walled cells) produces secondary phloem towards outer side and secondary xylem or wood towards inner side.

So, the correct option is ‘vascular cambium’.

a) Collenchymatous hypodermis -applicable because hypodermis is made up of collenchyma.

b) Polyarch xylem – not applicable, because, xylem and phloem are present on the same radius and side by side. It is found in monocot roots.

c) Presence of Casparian strips on endodermis – not applicable, because Casparian strips appear on the radial and tangential walls of the endodermis of roots.

d) Open vascular bundle – applicable, because, cambium is present between the xylem and phloem in the vascular bundles.

e) Presence of medullary rays – applicable – because, these are the extensions of medulla between the vascular bundles.

So, the correct option is ‘b and c’.

D. Stem and root apices

A.Monocot stem - Atactostele, collateral, conjoint, closed vascular bundles with endarch xylem is present.

a) Wrong – because in dicot root pericycle is meant for production of lateral roots and cambium whereas in monocot root it is pericycle is meant for lateral production only.

b) True – In dicot root stele is diarch to tetrarch, whereas in monocot root, stele is polyarchy.

c) True – In dicot root, cambium is developed laterally, whereas in monocot root, cambium is absent.

d) False – because, in dicot root is pith is poorly developed, whereas in monocot root pith is well developed.

So, the correct option is ‘a,d’.