Which hormone is stimulated by rising blood levels of k+, low blood levels of na+ and decreasing blood volume and blood pressure?

The hormone antidiuretic hormones is released due to high levels of potassium and high level of sodium ions. The release causes retention of water by the kidneys and leads to assure the levels of electrolytes in the body. Aldosterone is also responsible for maintaining sodium levels in the body. 

Stomata close when the guard cells lose water and become flaccid. This occurs because potassium ions move back out of the guard cell, followed by water that lowers the pressure in the guard cell. POP-UP –Many plant leaves have stomata only on their lower surface to help avoid water loss.