Question

What do you mean by a closed vascular bundle?
(a)Presence of cambium
(b)Absence of cambium
(c)Presence of periderm
(d)None of these

Answer 1

Hint: The closed vascular bundles are generally found in the leaves and monocot stem. They are not capable of secondary growth. In monocots, the vascular bundles are the collateral, conjoint, and closed type.

Complete answer:
A closed vascular bundle means that there is an absence of a cambium. They are not capable of forming the secondary xylem and phloem tissues. In monocots, the xylem is found within the inner side while the phloem is present outside and xylem and phloem are arranged side by side within the same radius which aren't separated by the cambium.
Addition information:
The difference between open vascular bundles and closed vascular bundles are-

Open vascular bundles	Closed vascular bundles
In open vascular bundles, Cambium is present between the xylem and phloem.	In closed vascular bundles, Cambium is absent.
It is capable of forming secondary xylem and phloem tissues.	It is not capable of forming the secondary xylem and phloem tissues.
It is found in dicotyledonous plants.	It is found in monocotyledonous plants.
It can be collateral and bi-collateral.	It can be collateral or concentric.

So, the correct answer is ‘Absence of cambium’.

Note:
A vascular bundle is a portion of the transport system in vascular plants. The transport itself happens in plant tissue, which exists in two forms: xylem and phloem. Both these tissues are present during a vascular bundle, which additionally will include supporting and protective tissues.