question_answer 5)

Cut a transverse section of young stem of a plant from your school garden and observe it under the microscope. How would you ascertain whether it is a monocot stem or a dicot stem? Give reasons.

Answer:

Transverse section of a monocot stem possess following Characters (i) Dumbbell-shaped guard cells in stomata in epidermis. (ii) Sclerenchymatous hypodermis. (iii) No concentric arrangement of internal tissues. (iv) Uniform ground tissue showing no tissue differentiation. (v) More than 8 scattered vascular bundles. (vi) Bundle sheath is present. (vii) No secondary growth normally. (viii) Xylem vessels arranged in Y-shaped manner. (ix) Protoxylem cavity usually present in vascular tissues. Transverse section of a dicot stem has following characters (i) Kidney-shaped guard cells in stomata present in epidermis. (ii) Collenchymatous hypodermis. (iii) Concentric arrangement of internal tissues. (iv) Differentiation of ground tissue into cortex, endodermis, pericycle and pith. (v) The vascular bundles are arranged in a ring. (vi) Conjoint collateral and open vascular bundles. (vii) Without bundle sheath. (viii) Secondary growth takes place. (ix) Xylem vessels arranged in rows.