Question

The diagram shows a root hair cell. What shows that it is a plant cell?

A) It has a large surface area
B) It has a large vacuole
C) It has no cell membrane
D) It has no cell wall.

Answer 1

Hint: Plant cells are eukaryotic cells with cell walls present around them. They also have a distinct nucleus with nuclear material surrounded by a nuclear membrane. The amount of DNA is comparatively higher in eukaryotic cells than in prokaryotic one. The nucleolus is also present.

Complete answer:
The correct option is (b) It has a large vacuole.
a) It has a large surface area- Although it has a large surface area, this does not distinguish a plant cell from any other cell.
b) It has no cell membrane- All the plant cells have a cell membrane. So this one is an incorrect option.
c) It has no cell wall- All the plant cells have a cell wall surrounding them, so this is also an incorrect option.

The epidermis or epiblema is the outermost layer of the body. It is usually single-layered. The outer walls of many epidermal cells protrude outwards in the form of tubular elongations. These unicellular tubular extensions are called root hairs which help in the absorption of water and minerals from the soil. Cuticles and stomata are present in a dicot root while they are absent in a monocot root.

Cortex is present below the epidermis and upto the epidermis, several layers of parenchymatous cells are present which comprise the cortex. These cells are thin-walled and are loosely packed which allows the free movement of water through them. Such an arrangement offers no resistance to water movement. The hypodermis is absent in a monocot root.

The endodermis is the innermost layer of the cortex which acts as a border between the cortex and the stele. All tissues on the inner side of the endodermis such as pericycle, vascular bundles and pith constitute the stele. Endodermis comprises a single layer of barrel-shaped cells in dicot and monocot roots which possess a special thickening of waxy material suberin in their radial and tangential walls called Casparian strips.

Note: Pith is found in the entire centre. It is made up of parenchymatous cells which have intercellular spaces. Pith is not well developed in the roots of dicot plants. It is small and inconspicuous in them while in monocot roots, it is large and well developed.