5 Marks Questions

Question

Draw illustrations to bring out the anatomical difference between (a) Monocot root and Dicot root (b) Monocot stem and Dicot stem

Vidyadip · Accepted Answer

Features	Monocot root	Dicot root
(i) Cortex	Comparatively narrow.	Very wide.
(ii) Endodermis	Less thickened and casparian strips are more prominent.	Later become highly thickened. Casparian strips are visible only in young root.
(iii) Passage cells	Generally absent.	Generally occur opposite the proto-xylem point.
(iv) Pericycle	Produces lateral roots, cork cambium and part of the vascular cambium.	Produces lateral roots only.
(v) Vascular bundles	2 to 5 or some-times 8.	8 or more in number.
(vi) Pith	Either absent or very small	Well-developed.

Features	Monocotyledonous stem	Dicotyledonous stem
(i) Vascular bundles	(a) Scattered (b) Conjoint, collateral, closed. (c) Bundle sheath usually present. (d) Phloem parenchyma absent. (e) Xylem vessels arranged either in Y or V shaped manner.	(a) Vascular bundles in ring (b) Conjoint, collateral or bicollateral and open. (c) Bundle sheath absent. (d) Phloem parenchyma present. (e) Not so.
(ii) Pith (Medulla)	Absent	Made up of parenchymatous cells situated in the centre of stem.
(iii) Ground tissue	Ground tissue is not differentiated into the cortex and pith.	Differentiated into the cortex and pith.
(iv) Hypodermis	Usually sclerenchymatous	Collenchymatous.
(v) Endodermis	Absent	One layered, starchy sheath which is usually not well differentiated.
(vi) Pericycle	Absent	Made up of one or more layers of parenchymatous and/or sclerenchymatous cells.
(vii) Medullary rays	Absent	Found in between vascular bundles.

Answer