Models Showing Accumulation

Abstract

Models consisting of a non-aqueous layer separating 2 aqueous solutions (the inner being more acid than the outer) show the following points of resemblance to Valonia:

(1) Penetration from the outer into the inner aqueous solution (artificial sap) is in the following order K > Na > Mg > Ca. Also Cl > SO₄.

(2) Instead of equilibrium a steady state is reached in which the artificial cell “sap” increases in volume but remains approximately constant in composition.

(3) Osmotic pressure and K-concentration become greater inside than outside.

(4) In certain models the “sap” contains CO₂. As potassium enters and KHCO₃ is formed the osmotic pressure rises. Although CO₂ is regarded as a waste product in organisms it acts in this case to increase the energy stored in the cell.