Opening Stomata Mechanism

Question 1

Guard Cells

Answer 1

• open when gain water as become turgid
• gain water through osmosis
• decrease in water potential in guard cells is required for water to enter cells by osmosis

Question 2

Light Response

Answer 2

• ATP in guard cells surface membrane actively transport H+ ions out of Guard cell
• this leaves inside of GC negatively charged compared to the outside
• causes channel proteins in GC surface membranes to open

Question 3

Potassium ions

Answer 3

• K+ ions move down the electrical gradient and enter the GC
• K+ ions also diffuse into the GC down the concentration gradient
• influx of K+ ions increases the solute concentration inside the GC lowering the water potential

Question 4

Electrochemical Gradient

Answer 4

-combination of electrical gradient and concentration gradient

Question 5

Water Entering

Answer 5

• water enters GC by osmosis through aquaporins in GC surface membranes
• most of the water enters the vacuoles causing them to increase in size

Question 6

Increasing turgor pressure

Answer 6

• causes stoma to open
• bonds of cellulose microfibrils only allow the GC to increase in length
• thin outer walls of gc bond more easily than thik inner walls
• causes GC to become curved opening up the stoma