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  Stoma
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A: epidermal cell
B: guard cell
C: stoma

      
Singular: stoma (C above)
Plural: stomata

     
These are holes or openings (C) in the leaves that enable transpiration to occur.

In addition to water vapour, other gases in the air also move in and out the leaves through stomata. Examples of the gases are oxygen and carbon dioxide which diffuse in and out during the processes of respiration and photosynthesis.
   
Tw
o guard cells (B) control the size of a stoma (C) by becoming turgid (having more water) or flaccid (having less water). When the guard cells are turgid, the stoma opens and becomes bigger in size. When the guard cells are flaccid, the stoma becomes smaller.

The size of the stoma controls the amount of water lost from inside the leaf during
transpiration.

The cells of the epidermis of the leaf surrounding the stoma are called the epidermal cells (A).
 
Mo
re stomata are found on the bottom surface of the leaves. The cells in the epidermis of the leaf surrounding the stoma and guard cells are known as the epidermal cells.


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Liang-liang Stoma
       
Stoma (C) merupakan liang-liang pada daun yang membolehkan transpirasi berlaku.

Selain daripada wap air, gas-gas
udara lain juga bergerak masuk dan keluar stoma. Contoh-contoh gas yang meresap melalui stoma ialah oksigen dan karbon dioksida yang digunakan untuk proses respirasi dan proses fotosintesis.

Dua sel dinding (B) mengawal saiz liang stoma. Apabila sel-sel ini cekang, liang stoma membesar. Apabila sel-sel ini menjadi lembik, liang stoma mengecil.
 
Saiz stoma mengawal kuantiti air yang hilang daripada dalam daun semasa
transpirasi.

Lebih banyak liang-liang stoma terdapat pada permukaan bawah daun. Sel-sel pada epidermis daun yang menyempadani liang stoma dan sel-sel dinding adalah dikenali sebagai sel epidermis (A).


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