Question

Stomata in grass leaf are
(a) Rectangular
(b) Kidney shaped
(c) Dumb-bell shaped
(d) Barrel-shaped

Answer 1

Hint: It consists of epidermal guard cells flanking a pore and overlying airspace in the internal photosynthetic tissue. It is adjustable valves through which atmospheric gases like ${ CO }_{ 2 }$ or, unfortunately, ozone enters the plant. It also serves as exit points for water that has journeyed from the soil to the plant.

Complete answer:
Stomata are cell structures present on the epidermis of leaves, each limited by two guard cells. It is normally present in vascular plants. Stomata open and near to permit ${ CO }_{ 2 }$ in and ${ O }_{ 2 }$ out. Stomata have a dumb-bell shape.

Additional Information: Grasses compose their stomata in organized lines running along the length of the leaf. However, this arrangement in files is not unique to grasses, if we zoom in to the individual stomatal complexes, two characteristics stand out. Firstly, as opposed to the kidney-shaped guard cells basic to most plants, grass guard cells have a unique ‘dumbbell’ shape. Furthermore, grass guard cells are personally associated with their neighbors, the subsidiary cells. By definition, subsidiary cells need just to be promptly nearby to guard cells and 'morphologically distinct' from other epidermal cells. However, what makes grass subsidiary cells so special is the degree to which their shape, signal response, and biochemistry are interlaced with (and often reciprocal to) those of the guard cells.
So the correct answer is ‘Dumb-bell shaped’.

Note: Grass stomata are fast and responsive, and their distinctive stomatal morphology likely provided the change necessary to give grasses the evolutionary edge in their establishment across the globe. Work with agronomically significant grasses like rice (Oryza sativa), barley (Hordeum vulgare), and maize (Zea mays).