Question

Monocot stem has
(a)Bicollateral closed vascular bundles
(b)Bicollateral open vascular bundles
(c)Collateral open vascular bundles
(d)Collateral closed vascular bundles

Answer 1

Hint: Stem has both vascular bundles in which a strand of phloem is present external to the strand of xylem on the same radius side by side. Secondary growth is absent in monocots.

Complete answer:
The xylem elements are arranged in the shape of “v” where metaxylem elements form the arms of “v” and protoxylem elements occupy at the junction of “v”. The protoxylem is arranged toward the interior and the metaxylem is arranged towards the exterior. The vascular tissue system of monocot has a closed bundle because cambium is absent and it is composed of xylem and phloem. The phloem is situated outer to xylem between the arms of “v”. Thus, the vascular tissue system of monocot is conjoint, collateral, and closed.

Additional Information: -The monocot stem has four tissue systems which contains: dermal tissue system, hypodermal tissue system, ground tissue system and vascular tissue system whereas in dicot the ground tissue system is differentiated into cortex and endodermis but not in monocot.
-The xylem of monocot is endarch which means xylem is formed from inner cells outward.
Phloem is composed of sieve tubes and companion cells where parenchyma is absent.

So, the correct answer is, ‘Collateral closed vascular bundles.’

Note: -The dicot stem has ground tissue differentiated to stellar and extra stellar and vascular bundles are present in limited numbers.
-The dicot stem has conjoint, collateral, and open vascular tissue system.