Respiration In Plants

Respiration In Plants : Plants have tiny pores called stomata found on the underside of a leaf. Air containing carbon dioxide and oxygen enters the plant through these openings where it gets used in photosynthesis and respiration. Plant that float in water, e.g. water Lily, have stomata on the upper sides of the Leaves. Underwater plants such as tape grass have no stomata. They breathe in oxygen dissolved in water through their body surfaces.

A stoma (from Greek "mouth", plural "stomata"), also called a stomate (plural "stomates") is a pore, found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the stomatal opening.

The term is usually used collectively to refer to the entire stomatal complex, consisting of the paired guard cells and the pore itself, which is referred to as the stomatal aperture.Air, containing oxygen, which is used in respiration, and carbon dioxide, which is used in photosynthesis passes through stomata by gaseous diffussion. Water vapours diffuses through the stomata into the atmosphere in a process called transpiration.

Dicotyledons usually have more stomata on the lower surface of the leaves than the upper surface.

Monocotyledons such as onion, oat and maize may have about the same number of stomata on both leaf surfaces^.

In plants with floating leaves, stomata may be found only on the upper epidermis and submerged leaves may lack stomata entirely.

Most tree species have stomata only on the lower leaf surface.

Leaves with stomata on both the upper and lower leaf surfaces are called amphistomatous leaves.

Leaves with stomata only on the lower surface are hypostomatous.

Leaves with stomata only on the upper surface are epistomatous or hyperstomatous.

Size varies across species, with end-to-end lengths ranging from 10 to 80 µm. and width ranging from a few to 50 µm.

Sample Questions

(More Questions for each concept available in Login)

Question : 1

Plants have ______________ pores called stomata found on the underside of leaf.
A. Tiny		B. Large
C. Circular		D. Rectangular
Right Option : A
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Question : 2

In which of the following plants the stomata are present on the lower surface of the leaf ?
A. Water lily	B. Tape grass	C. Lotus	D. Sunflower
Right Option : D
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