All of the following are true regarding Donnan effect except
**Core Concept**
The Donnan effect, also known as the Donnan equilibrium, is a phenomenon in which the distribution of ions and charged particles across a semipermeable membrane is influenced by the presence of impermeable ions. This effect is a result of the equilibrium between the concentration of charged particles and the electrochemical potential across the membrane.
**Why the Correct Answer is Right**
The Donnan effect occurs in a solution containing impermeable ions, such as proteins or large organic molecules, that are unable to cross the semipermeable membrane. The presence of these impermeable ions creates an electric potential difference across the membrane, which in turn affects the distribution of permeable ions. The Donnan effect can be observed in various biological systems, including the blood-brain barrier and the glomerular filtration barrier in the kidneys.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as the Donnan effect is indeed influenced by the presence of impermeable ions.
**Option B:** This option is incorrect as the Donnan effect is a result of the equilibrium between the concentration of charged particles and the electrochemical potential across the membrane.
**Option C:** This option is incorrect as the Donnan effect can be observed in various biological systems, including the blood-brain barrier and the glomerular filtration barrier in the kidneys.
**Clinical Pearl / High-Yield Fact**
The Donnan effect is an important concept in understanding the behavior of charged particles across biological membranes, and it has significant implications for the transport of ions and molecules in various physiological and pathological conditions.
**Correct Answer:** A.