A:
a. Exarch: When the protoxylem is present towards the periphery and metaxylem is present towards the center.
Endarch: When the protoxylem is present towards the center and the metaxylem towards the periphery.
b. Stele: Stele is the central part of the root or stems.
Vascular bundle: Vascular bundle is the part of stele.
c. Protoxylem: The xylem that formed earlier is known as Protoxylem.
Metaxylem: The xylem that formed later is metaxylem.
d. Interfascicular cambium: It is present between the primary xylem and primary phloem.
Intrafascicular: It is present in between the two vascular bundles.
e. Open vascular bundles: A vascular bundle which is capable secondary growth.
Closed vascular bundles: A vascular bundle which is not capable of secondary growth.
f. Stem hair: 1. These are multicellular.
2. Function is to increase the surface for absorption.
Root hair: 1. These are unicellular.
2. Function is to prevent water loss.