Tag: internal structure of root, stem and leaf

Eustele - In this arrangement, the primary vascular tissue consists of vascular bundles, usually in one or two rings around the pith. In addition to being found in stems, the eustele appears in the roots of monocot flowering plants. The vascular bundles in a eustele can be collateral with the phloem on only one side of the xylem or bicollateral with phloem on both sides of the xylem, as in some Solanaceae. So, eustele is the characteristic of monocots and absent in dicots, pteridophytes and bryophytes. 
Thus, the correct answer is option A.

Endarch is the arrangement in which the protoxylem is directed towards the centre and metaxylem elements towards the periphery. The development of the xylems in this arrangement follows the centrifugal pattern. It is the characteristics of the stem of flowering plants. 

Cocos nucifera, the coconut palm, is a monocot perennial member of the Arecaceae (palm family), cultivated in tropical areas worldwide for its fruit and fiber. Coir is a natural fibre extracted from the husk of coconut and used in products such as floor mats, doormats, brushes, mattresses, etc. Coir is the fibrous material found between the hard, internal shell and the outer coat of a coconut. Other uses of brown coir are in upholstery padding, sacking and horticulture. Thus, option A is correct. 

Development of xylem from the periphery to the centre is called centripetal xylem. It is found in roots.

So, the correct option is ‘root’.

Monocot root vascular bundles are radial in the arrangement. There are eight types of bundles each of xylem and phloem. Thus the condition is described as the polyarch. Xylem is detailed as an exarch.

Monocot stem vascular bundles are many in number and the xylem is the endarch.

Dicot stem vascular bundles are also eight in number but arranged in the form of a broken ring. The vascular bundles are conjoint, collateral and open. Xylem is on the inner surface and phloem on the outer surface. Xylem is described as an endarch.

Dicot root vascular bundles are described as radial and tetrarch. There are four bundles each of xylem and phloem occurring alternately. Xylem is described as an exarch.

So, the correct answer is 'Monocot root'

So, the correct answer is B.

A. Epiblema – root epidermis with root hairs is called epiblema

B. Pericycle – outer most part of the stele in roots and dicot stem, produces lateral branches

C. Cortex – middle of root and dicot stem internally

D. Endodermis – inner most part of the cortex

So, the correct option is ‘Pericycle'

Endodermal cells without casparian strips or bands are called passage cells. These are present opposite to the protoxylem cells. These are found in both dicot root and monocot root.

The anatomy of dicot root differs from monocot root, in activity of pericycle, no. of xylem strands, presence of medulla, activity of conjunctive tissue.  

In monocot root, the vascular bundles are usually more than six in number. Pith is large and parenchymatous. The parenchyma of the pith become lignified and sclerenchymatous.