Question

Casparian Strips are found on the
A.Walls of pericycle cells
B.Walls of endodermal cells
C.Walls of epidermal cells
D.Walls of bundle sheath cells

Answer 1

Hint: Casparian strip is defined as the central, innermost layer of the cortex in land plants that contains Casparian strips. This part of the plant is observed as cylinder-shaped and composed of compact living cells and the radial walls of these are water-resistant.

Complete answer:
Endodermis is characterised by the presence of a special thickened' band in their wall called a casparian strip. This thickening was first observed by Caspary, hence the name. This thickening appears on the radial as well as on the tangential walls of endodermal cells. This band-like structure is generally formed by the deposition of a water-impermeable waxy material suberin. Hence, walls of endodermal cells are suberized. Due to the presence of casparian strips, the endodermis is impervious to water. A distinct endodermis is a constant feature of roots of all plants but in stems it is not very distinct.

Now let us collect information from given options:
1.Walls of pericycle cells: It is the outermost portion of stele. It is a cylinder of thin-walled parenchymatous or sometimes thick-walled sclerenchymatous tissue. It may be single-layered to multi-layered. The cells may be thin-walled to thick-walled. Pericycles may be present in the form of patches also. Pericycle is not present in monocotyledonous stems.

2.Walls of endodermal cells: Casparian strips are usually present in the Endodermis. It is a cell wall material that is present in the radial and transverse walls of the endodermis of roots. It is composed of suberin and sometimes of lignin.

3.Walls of epidermal cells: The outside of the epidermis is often covered with a waxy thick layer called the cuticle but do not have casparian strips which prevents the loss of water because of deposition of a waxy substance called cutting on the outer walls of cells. Cuticle is absent in roots and hydrophyte.

4.Walls of bundle sheath cells: Spongy parenchyma lies below the palisade parenchyma and extends up to the lower epidermis, hence it is abaxially placed. It is made up of oval or rounded cells which are irregularly arranged without any particular arrangement called as bundle sheath cells and do not have casparian strips.

Hence, the correct answer is option (B)

Note: The Casparian strip is first named after Robert Caspary. The Casparian strip is a waterproof and water-resistant tissue. The Casparian strip helps to stop the water from entering the pericycle except through the cytoplasm of endodermal cells and is important in producing root pressure.