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Gas exchange 1. Water flows in and out of the guard cells by the process of: diffusion electrolysis osmosis hydrolysis 2. Gases flow in and out of leaves by the process of: diffusion hydrolysis electrolysis osmosis 3. The plant hormone that triggers potassium ion withdrawal from guard cells acetic acid amino acid ascorbic acid abscissic acid 4. Withdrawing potassium ions from guard cells: closes the stoma reduces water potential opens the stoma has no effect on the stoma 5. The inner walls of stomata are held rigid by: sclerenchyma cellulose microfibrils spongy mesophylls palisade mesophylls 6. When guard cells fill up with water they are said to become: turbid turgid turbulent traumatized 7. The ions transported into guard cells to close the stomata are: OH- Na+ K+ Cl- 8. Stomata close when guard cells: contain no water contain no potassium ions are not turgid are turgid 9. The effect of adding potassium ions on the water potential in guard cells is: the water potential is exactly zero the water potential decreases the water potential is unaltered the water potential increases 10. Stomata are situated in the gaps between: xylem cells phloem cells palisade cells guard cells