Question

Close type of vascular bundle lacks?
(a)Xylem
(b)Sclerenchyma
(c)Phloem
(d)Cambium

Answer 1

Closed vascular bundles lack a layer of tissue that produces partially undifferentiated cells and helps in secondary growth. Closed type vascular bundles are commonly found in monocot plants.

Complete step-by-step answer:
The closed type and open type vascular bundles are differentiated by the presence and absence of cambium. A cambium strip is generally found in vascular bundles of root and shoots of dicot plants. If the vascular bundle does not contain the cambium, then such type of vascular bundle is known as closed type vascular bundle. In such type of vascular bundles, there is no clear demarcation of xylem and phloem tissues (Figure).
These are present in the leaves and stem of the plant. These are tube-like structures responsible for the transport of minerals, water, and food from where it is absorbed or produced to parts where it is needed. Minerals and ions are transported via xylem channels while food is transferred via phloem channels.

Additional Information: -The stele is the central part of the leaves and stems of the plant.
-Cambium is the feature of dicot plants.
-Cambium is a strip of thin-walled cells present between xylem and phloem.
-If the vascular bundle contains cambium, such vascular bundles are called open type vascular bundles.
-Based on the orientation of xylem and phloem, the individual vascular bundle of the stele is classified into three types: collateral, bicollateral, and concentric vascular bundles.
-Concentric vascular bundles are of two types: amphivasal and amphicribral.
So, the correct answer is ‘cambium.’

Note: Cambium cells are meristematic in nature and it gives rise to the secondary xylem on the inner side and the secondary phloem on the outer side in woody plants. The collateral vascular bundle has a single strip of cambium while the bicollateral vascular bundle has two strips of cambium.