What defines a conjoint vascular bundle?

Correct option is A

Sol.

• The correct answer is (a) Xylem and phloem present on the same radius.
  ​Explanation :​
  
• A conjoint vascular bundle is defined by the arrangement where both xylem (responsible for water conduction) and phloem (responsible for food transport) are located on the same radius within the vascular bundle. In these bundles, xylem and phloem are found together, which helps in the efficient transport of water, nutrients, and sugars.

Information Booster:

• Conjoint vascular bundles are typically found in dicots and monocots in plants. These bundles play a crucial role in the transport of materials across the plant.
• In dicots, the xylem and phloem are usually arranged in a ring-like structure, with phloem on the outer side and xylem on the inner side, though both are still present within the same vascular bundle.
• In monocots, vascular bundles are scattered in the stem, and xylem and phloem remain conjoint but often lack a specific arrangement in the form of a ring.
• Vascular cambium is the tissue responsible for the secondary growth of vascular bundles, and its presence or absence does not affect the definition of a conjoint vascular bundle.
• Concentric vascular bundles, where xylem is surrounded by phloem or vice versa, are distinct from conjoint bundles, and they are found in some monocot stems like in members of the Liliaceae family.

Additional Information:

• (b) Xylem and phloem alternate along the radii: This option describes a collateral vascular bundle rather than a conjoint one. In collateral bundles, xylem and phloem alternate, but this is not the specific definition of conjoint bundles.
• (c) Cambium is absent: Cambium is not directly related to the definition of a conjoint vascular bundle. The cambium is responsible for the growth of vascular tissues, and its absence does not define the arrangement of xylem and phloem in a bundle.
• (d) Xylem only on the outer side: This option is incorrect because, in a conjoint vascular bundle, xylem is typically found on the inner side, and phloem is on the outer side (in many plants), but both are still on the same radius. This description would apply to a different type of vascular arrangement, not conjoint.