Main Organ of Gaseous Exchange

Stoma

Pores that are located on the leaf lower epidermis

Guard cell

A pair of cell that regulate the opening and closing of stoma

The condition of the guard cell is influenced by two things

Intake of potassium ion & the concentration of sucrose in the cell sap

The condition that causes the stoma to open

When potassium and sucrose concentration rise in the guard cell and cause water to permeate into the cell by osmosis.

The condition that causes the stoma to close

When the concentration of potassium and sucrose ions decreases in the control cell causing water to osmotically diffuse out.

Water diffuses in and out of the guard cell through

Osmosis

The condition of the stoma when the plant is dehydrated

The condition of the stoma when the plant has enough water

Effect of flaccid guard cells

Effect of turgid guard cells