Tag: root - external morphology

Plants can absorb nitrate or nitrite from the soil via their root hairs. If nitrate is absorbed, it is first reduced to nitrite ions and Ammonium ions for incorporation into various compounds.

The three principal tissues of the root vascular cylinder, cortex and epidermis originate from three groups of initial cells or histogens, in the apical meristem plerome, periblem and dermatogen respectively. A fourth histogen, the calyptrogen produces the root cap.        
So, the correct answer is 'root cap'

Pandanus has stilt roots with very large conspicuous aerial root cap. These are the largest and multiple persistent root caps.

The adventitious roots found in the epiphytes are known as the epiphytic root. These roots hang freely in the air and absorb the moisture from the air by a special type of tissue called as velamen. Epiphytic plants are sometimes called as air plants because they do not have roots in the soil. For example, Vanda.

In plants like Arceuthobium, Rajflesia, Sapria, Podostemon, shoot develops for flowering otherwise roots form main part of the plant.

Passage cells are endodermal cells of older monocot roots, which have retained thin walls and casparian strips. They are not suberized and waterproof. They allow symplastic flow of solutes, such as calcium and magnesium into the stele.

Calyptrogen is a histogen which produces the root cap.
Thus, the correct answer is option A.

The thick waxy layer covers the surface of aerial organs is termed as Cuticle. It is composed of a waxy substance called cutin. It is thin in mesophytes and extremely thick in xerophytes. The cuticle is absent in hydrophytes and underground organs and young roots. Other three options the bearing Cuticle.

So, the correct option is 'Young roots'.

The correct option is B.