Question

Shoot apex is protected by
(a) Root apex
(b) Shoot cap
(c) Calyptra
(d) Primordial leaves

Answer 1

Hint: Shoot apex is an apical meristem that initiates from a group of cells and the lenticular ethical cells of the leaf lose its entity which gives rise to a group of columnar prismatic cells.

Complete answer:
Shoot Apex is protected by primordial leaves. The root cap consists of the parenchymatous cap like multicellular structures which covers the root apical Meristem and secrete mucilage to lubricate the path of the root in the soil. The shoot apical Meristem is a conical structure that gives rise to primordial leaves at intervals and in turn, the primordial leaves protect the shoot Apex. Leaf and flower produce primordial cells at the shoot apical Meristem and it develops in plants where it is critical to the proper positioning and development of plant organs and cells. This process is intricately regulated by the set of genes that affect the positioning and differentiation of the primordium. They are involved in defining the borders of the newly formed primordium and auxin is implicated in the process with the new primordium which is being initiated at the placenta where the auxin concentration is the highest.

Additional information:
The initiation of apical bud from the rachis tip involves shoot Apex organization and the leaf initiates from a group of cells. The leaf is acropetal in its maturation stage and lenticular apical cells of the leaf lose its entity which gives rise to a group of prismatic cells that are inverted pyramid apical cells which differentiates during the conversion of leaf step into a shoot bud. The primordia did not differ greatly in shape and size but the mature leaves are tremendously and largely consequence differential patterns of cell division and expansion which indicates the key regulatory genes that control each step.

So, the correct answer is 'Primordial leaves'.

Note:
After the development of primordium, the protein becomes basally- oriented which evacuates oxygen from the surface to the inner tissues and transports it inwards towards the pro vascular tissue.