Tag: internal structure of stem(dicot and monocot)

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.Polyarch – stele with many xylem strands, is found in monocot roots.

B.Monoarch – stele with one xylem strand, is found in Trapa.

C.Endarch – protoxylem is present towards the centre, and metaxylem is present towards the periphery, is found in dicot and monocot stems.

D.Exarch – protoxylem is towards the periphery, metaxylem is towards the centre, is found in dicot and monocot roots.

So, the correct option is ‘Endarch’.

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

A-The outer light coloured, functional secondary xylem or wood, takes up in the conduction of water of sap is called sapwood or alburnum.

The anatomy of dicot root and dicot stem differ in many characters. In dicot, root epidermis contains root hairs, whereas in epidermis contains trichomes, cuticle and stomata. In dicot, root cortex shows general cortex and endodermis, whereas in dicot stem cortex shows hypodermis, general cortex and endodermis.

In dicot, root hypodermis is absent whereas, in dicot stem, hypodermis is present.

In dicot root endodermis shows Casparian bands, whereas in dicot stem endodermis contains starch grains in its cells.

In dicot root pericycle is parenchymatous, take part in the lateral formation and secondary growth, whereas in dicot stem, pericycle is discontinuous, sclerenchymatous, present in the form of patches over the vascular bundles.

In dicot root, vascular bundles are radial, whereas in dicot stem vascular bundles are collateral, conjoint, open

In dicot, root xylem is exarch, whereas in dicot stem xylem is endarch.

In dicot, root medulla is reduced, whereas in dicot stem is xylem is endarch.

In dicot root, conjunctive tissue is present, whereas, in dicot stem, medullary rays are present.

So, the correct option is ‘Protoxylem’

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’.

secondary xylem is also called wood. Any tissue located to the "outside" of the vascular cambium is considered bark and tissue side is called as wood.