Casparian bands are present on the

The correct answer is Radial and inner tangential walls of endodermis

Concept:

• Casparian bands, or Casparian strips, are a characteristic feature of the endodermis in plant roots.
• They are made up of suberin and lignin, which are hydrophobic substances, and they play a crucial role in regulating the flow of water and nutrients into the vascular system of the plant.
• The primary function of Casparian bands is to block the passive flow of materials such as water and solutes into the stele (vascular cylinder) through the cell walls, thus ensuring that all substances must pass through the cytoplasm of endodermal cells, which can selectively control the uptake.

Explanation:

• Inner tangential wall of testa epidermis: The testa is the seed coat, and its epidermis does not have Casparian bands. Casparian bands are specific to the endodermis of roots.
• Radial and inner tangential walls of endodermis: Correct. Casparian bands are found on the radial and inner tangential walls of endodermal cells. This positioning creates a barrier to passive flow into the vascular system.

• Radial walls of pericycle: The pericycle is a layer of cells just inside the endodermis but does not have Casparian bands. The pericycle is involved in the formation of lateral roots.
• Radial and outer tangential walls of endodermis: Incorrect. Casparian bands are not found on the outer tangential walls; they are located on the radial and inner tangential walls.