Question

Following are the differences between monocot and dicot stem. Which ones are correct?

	Property	Monocot stem	Dicot stem
(i)	Hypodermis	Sclerenchymatous	Collenchymatous
(ii)	Xylem	Exarch	Endarch
(iii)	Pith	Absent	Present
(iv)	Bundle Sheath	Sclerenchymatous	Parenchymatous

• A. i and ii
• B. iii and iv
• C. i and iii
• D. ii and iv

Answer 1

Answer: (C)

In dicot stem, hypodermis consists of a few layers of collenchymatous cells just below the epidermis, which provide mechanical strength to the young stem. The monocot stem has a sclerenchymatous hypodermis.
In stems (monocots and dicots), the protoxylem lies towards the centre (pith) and the metaxylem lies towards the periphery of the organ. This type of primary xylem is called endarch. In roots (monocots and dicots), the protoxylem lies towards periphery and metaxylem lies towards the centre. Such arrangement of primary xylem is called exarch. In dicot stem, a large number of vascular bundles are arranged in a ring. It also has a large number of rounded, parenchymatous cells with large intercellular spaces which occupy the central portion of the stem which constitute the pith. Moncot stems have a large number of scattered vascular bundles, hence pith is absent. In monocot stem each vascular bundle is surrounded by a sclerenchymatous bundle sheath. Bundle sheaths are absent in dicot stem