NEET BIOLOGY

Detailed explanation-1: -The first formed primary xylem is called protoxylem and the later formed primary xylem is called metaxylem. In stems, the protoxylem lies towards the centre (pith) and the metaxylem lies towards the peripheryof the organ. This type of primary xylem is called endarch.

Detailed explanation-2: –In exarch condition, the protoxylem (the first-formed xylem) lies towards the periphery and the metaxylem (the later-formed xylem) lies towards the center (pith). Hence, the youngest lies closest to the center in this type of arrangement. So, the answer is, “Exarch.”

Detailed explanation-3: -In roots, the protoxylem lies towards periphery and metaxylem lies towards the centre. Such arrangement of primary xylem is called exarch. In stems, the protoxylem lies towards the centre and the metaxylem lies towards the periphery of the organ. This type of primary xylem is called endarch.

Detailed explanation-4: -> Endarch: This type of primary Xylem is present in the stem, while in this endarch type, protoxylem is present towards Pith, and metaxylem is present towards the periphery. Presence of endarch xylem results in a centrifugal pattern of arrangement. An example is a stem.

Detailed explanation-5: -Protoxylem is the primary xylem that develops first during primary growth. Metaxylem is formed after the protoxylem during primary growth in the xylem. Growth. It grows before the maturation of other plant organs. It grows after the maturation of all plant organs.