Anatomy of Flowering Plants Test - 89

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’

The inner most part of the cortex in root and dicot stem is endodermis. it is single layered. Cells are barrel shaped and thick walled. On the radial walls and tangential walls, ligno suberised thickenings are present. These are called Casparian thickenings. Some of the endodermal cells lack casparian bands. These are called passage cells. These cells are present opposite to the protoxylem cells. Endodermis acts as check point, and prevents the outflow of water and minerals from the stele into cortex, and also acts as a barrier in the inflow of water and mineral from cortex and stele.

So, the correct option is ‘Endodermis’.

I.Conjoint – applicable – because xylem and phloem are present side by side in the vascular bundles.

II.Endarch protoxylem – applicable – because protoxylem is present towards medulla side and metaxylem is present towards the pericycle side.

III.Open – not applicable – because, cambium is absent between the xylem and phloem in the vascular bundles.

IV.Phloem parenchyma is absent – applicable – in the phloem of monocots phloem parenchyma is not present.

So, the correct option is ‘III’

• In a monocot root vascular tissues such as xylem and phloem are excess in number, whereas in dicot root, these tissues are limited in number
• Since monocot plants do not have a vascular cambium, the formation of secondary xylem and phloem do not take place which leads to the presence of large number of xylem bundles.
• Whereas, in dicot plants, the number of xylem and phloem are reduced due to the formation of vascular cambium.

Hence, as compared to a dicot root, a monocot root has many xylem bundles.

Cork cambium arises from outer most layer of the cortex which is the ground tissue. 

A lysigenous cavity is a type of intercellular space appearing through the dissolution of entire cells, which are therefore called lysigenous intercellular spaces. These cavities of intercellular spaces store up water, gases, and essential oils. So, the correct answer is option D.

The plumule is the embryonic extension that grows out to become the shoot system of the plant. The shoot apical meristem is the primary meristem and it is derived from the embryonic promeristem. It is situated at the top of the plumule and it forms the vegetative primary growth structures like branches and the leaves of the shoot system. 

Monocots have usually collateral vascular bundles, a type that is also called closed. The vascular bundle is enclosed by a sclerenchymatous bundle sheath of parenchyma cells.