Describe the internal structure of a dicot root with a labelled diagram.

1. 1 · Open in one line. A T.S. of a dicot root (bean) shows the epiblema, cortex, endodermis, pericycle, vascular tissue and a small or no pith.
2. 2 · Draw and label. [T.S. of bean root: root hairs, epiblema, cortex, endodermis with Casparian strip, passage cell, pericycle, protoxylem, metaxylem, phloem, conjunctive tissue]
3. 3 · Outer layers.
   • Epiblema: single layer, no cuticle, unicellular root hairs.
   • Cortex: many layers of parenchyma with intercellular spaces; stores food.
4. 4 · Endodermis and pericycle.
   • Endodermis: barrel-shaped cells with Casparian strips; passage cells opposite the protoxylem.
   • Pericycle: a single layer; forms lateral roots.
5. 5 · Vascular tissue. Radial bundles; xylem exarch and tetrarch; phloem between the xylem arms; conjunctive tissue between them; pith small or absent.
6. 6 · Real life. Root hairs of crops like paddy absorb water and minerals from the soil, so healthy roots mean healthy crops.
7. 7 · Close in one line. So the dicot root is built to absorb water and send it up through radial, exarch xylem.

Scoring tip: Draw the diagram first and use the same labels in your answer. Never forget the Casparian strip and passage cell labels.