Physical Properties of Protoplasm: The protoplasm exist either in semisolid jelly-like) state called .gel. due to suspended particles and various chemical bonds or may be nude .sol..
The colloidal protoplasm which is in gel form can change into sol form by solation and women can change into gel by gelation. These gel-sol conditions of colloidal system are prime for mechanical behaviour of cytoplasm.
(i) Protoplasm is translucent, odourless and polyphasic fluid.
(ii) It is a crystal colloid solution which is a mixture of chemical substances forming crystalloid i.e. true solution (sugars, salts, acids, bases) and others forming colloidal solution (Proteins and lipids)
(iii) It is the most important property of the protoplasm by which it exhibits three main phenomena namely Brownian movement, amoeboid movement and cytoplasmic streaming or cyclosis.Viscosity of protoplasm is 2-20 centipoises. The Refractive index of the protoplasm is 1.4.
(iv) The pH of the protoplasm is around 6.8, contain 90% water (10% in dormant seeds)
(v) Approximately 34 elements are present in protoplasm but only 13 elements are main or universal elements i.e. C, H, O, N, CI, Ca, P, Na, K, S, Mg, I and Fe. Carbon, Hydrogen,Oxygen and Nitrogen form the 96% of protoplasm.
(vi) Protoplasm is neither a good nor a bad conductor of electricity. It forms a delimiting membrane on coming in contact with water and solidifies when heated.
Cohesiveness: Particles or molecules of protoplasm are adhered with each other by forces, such as Van der Waal.s bonds, that hold long chains of molecules together. This property varies with the strength of these forces.
Contractility: The contractility of protoplasm is important for the absorption and removal of water especially stomatal operations.
Surface tension: The proteins and lipids of the protoplasm have less surface tension, hence they are found at the surface forming the membrane. On the other hand the chemical substances (NaCl) have high surface tension, so they occur in deeper parts of the cell protoplasm.
