Question

Closed vascular bundles are the ones which
A. Contain cambium
B. Lack cambium
C. Lack xylem
D. Possess lysigenous cavity

Answer 1

Hint: Vascular bundles are a part of the transport system in plants and consist of xylem and phloem. They are either closed or open depending on the presence of cambium.

Complete answer:
The correct answer is – B. Lack cambium
Closed vascular bundles are the ones that lack cambium.
Cambium is responsible for secondary growth and since it is not present in closed vascular bundles, there is no secondary growth.

Additional information:
The xylem and phloem are organized into vascular bundles which can either be termed be open or closed.
OPEN VASCULAR BUNDLES
In open vascular bundles, a strip of cambium is present between the xylem and the phloem. In this case, the word ‘Open’ implies ‘Open for secondary growth’. The cambium is called Fascicular Cambium.
This type of vascular bundle is found in dicotyledons.
CLOSED VASCULAR BUNDLES
In closed vascular bundles, there is a complete absence of cambium between the xylem and phloem. Since there is no secondary growth, here the word ‘Closed’ implies ‘Closed for secondary growth’.
This type of vascular bundle is found in monocotyledons.
The main function of vascular bundles is to transport water and minerals in the growth phases of the plant.
Xylem is the tissue that conducts water throughout the plant, whereas phloem is the tissue that conducts nutrients throughout the plant.

Note: As mentioned, the cambium facilitates secondary growth. Its cells divide to produce secondary xylem and secondary phloem cells.