2006-12-05 16:06:41 · 4 answers · asked by cathy 1 in Science & Mathematics ➔ Botany
The stomata are closed or opened by the surrounding cells, and they respond by this action at some stimulus as dust , excessive heat (when the evaporation and loss of water is high) and when cold temperatures also.
Dfriend :)
2006-12-05 17:36:44 · answer #1 · answered by Dfriend 3 · 1⤊ 0⤋
sunlight. presence of mineral ions in the plant. water. rate of transpiration. rate of water uptake.
well basically the first three work together. in the presence of SUNLIGHT photosynthesis occurs. with the energy, MINERAL IONS are pumped into the guard cells in the leaves. this causes an osmotic gradient to be set up and WATER enters the guard cells via osmosis. the guard cells become turgid, and due to the uneven thickness of the walls, they curve. the stoma opens.
well at night no photosynthesis occurs and thus the stoma closes.
the last two work together too. when the rate of transpiration is greater than the rate of water uptake, wilting occurs and the guard cells lose turgidity. thus the stoma closes.
when the rate of transpiration is lower than the rate of water uptake, osmotic pressure in the guard cells is maintained and the stoma remains open.
2006-12-06 01:34:21 · answer #2 · answered by maczh2002 2 · 0⤊ 0⤋
the cells surrounding the stomata influence itz opening and closing.
also the pressure or turgidity around also influences its opening and closing.
2006-12-05 17:27:43 · answer #3 · answered by rathan_babu 2 · 0⤊ 0⤋
the turgidity
2006-12-05 16:10:17 · answer #4 · answered by pigley 4 · 0⤊ 0⤋