Osmotic Potential: Definition, Examples, Equation, Solute & Pressure

What is Osmotic Potential?

Osmotic potential, also referred to as solute potential, is the most fundamental principle regarding studying the movement of water through biological systems. It refers to the ability of any solution to draw water into itself through a natural process called osmosis. This paper looks at some basic concepts regarding osmotic potential, its measurement, and its importance in plant physiology, among other biological processes.

Definition of Osmotic Potential

Osmotic potential is defined as the measure of water's tendency to move into a solution across a semipermeable membrane due to the presence of solutes. This is, therefore, an important factor in determining the direction and rate of water movement in and out of cells.

Relationship Between Osmotic Potential and Solute Concentration

The osmotic potential is directly related to the concentration of solutes in the solution. The higher the concentration of the solutes, the lower the osmotic potential, because the solutes decrease the potential energy of water molecules.

Formula for Osmotic Potential

Osmotic potential can be measured using the expression:

Ѱs = -iCRT

where:

• Ѱs is the osmotic potential,

• i is the ionisation constant,

• (C) is the concentration of the solute,

• (R) is the gas constant,

• (T) is the temperature in Kelvin.

The given formula derives the osmotic potential of any solution from its concentration and temperature.

Example Calculation

The formula is utilised in various laboratory experimental setups to measure the osmotic potential. For example, knowledge of the osmotic potential of plant cells may help ascertain the water intake and retention capacity of such cells.

Osmotic Potential in Plant Cells

Osmotic potential is among the few factors that have a great influence on plant physiology, as it varies the uptake of water by a plant cell and the turgor pressure that characterises it.

Osmotic Potential and Turgor Pressure

Turgor pressure is the pressure that is generated by that fluid—the vacuole—against the cell wall. The turgor pressure is directly under the influence of osmotic potential in the cell sap. In other words, if there is a high potential for osmosis within the cell sap, there is a correspondingly high turgor pressure to help support and maintain the shape of the cell with rigidity.

Water Potential

Water potential is the sum of both osmotic and pressure potentials, thus determining the direction of water movement. In plants, water always moves from an area of higher water potential to an area of low potential.

Osmotic Potential in Animal Cells

Osmotic potential in animal cells tenses the cellular hydration level and volume. Since an animal cell lacks a rigid cell wall, the osmotic potential within the cell rebalances the intracellular and extracellular fluids. The osmotic potential imbalance will result in either dehydration or edema and therefore affect cell function and general health.

Role In Kidney Function

The kidneys will change osmotic potential to maintain body fluid and electrolyte balance—a critical mechanism of homeostasis.

Osmotic Potential In Different Solutions

A knowledge of osmotic potential in different kinds of solutions will be useful in practical biology work.

Hypotonic Solution – water enters cell

A solution with less of a solute concentration than the cell's interior. This means there is inflowing water into the cell, and it becomes swollen.

Isotonic Solution – equilibrium

The concentration of the solutes is the same as that inside the cell. In such a solution, no net movement of water will take place.

Hypertonic Solution – water exits cell

Hypertonic solution is a solution with a higher concentration of solutes. Water rushes out from the cell, and the cell shrinks in size.

Applications In Medicine

These are some of the cardinal principles working in most medical practices, including intravenous fluid administration and drug delivery systems.

Osmotic Potential NEET MCQs (With Answers & Explanations)

The key concepts to be covered under this topic for different exams are:

• Formula for Osmotic Potential

• Water Potential

Practice Questions for NEET

Q1. The force with which a solution can cause endosmosis across a semipermable membrane depends on its

1. Osmotic pressure

2. Osmotic potential

3. Both a and b

4. None of these

Correct answer: 2) Osmotic potential

Explanation:

Osmotic potential is the pressure exerted by a solution to attract solvent molecules through a semipermeable membrane. It is a measure of the tendency of water to move into the solution due to the presence of solute particles. Hence, every solution that has some solute has an osmotic potential.

Hence, the correct answer is option 2) Osmotic potential.

Q2. Which of the following is equivalent to the osmotic pressure but is negative?

1. Water potential

2. Matrix potential

3. Osmotic potential

4. All of these

Correct answer: 3) Osmotic potential

Explanation:

The osmotic potential relates to the solution's ability to produce osmotic pressure, effectively hindering osmosis. When are solutes added to pure water, the free energy lowers since there are fewer free water molecules present. The potential represents the pressure with which an element attracts solvent molecules. Since every solution with solute has osmotic potential, it is equal to osmotic pressure and is regarded as a negative force.

Hence the correct answer is option 3) Osmotic potential.

Q3. Osmotic potential is a function of

1. Concentration of solutes in the solution

2. Temperature in Kelvin

3. Both a and b

4. None of these

Correct answer: 3) Both a and b

Explanation:

Osmotic potential (Ψₛ) is a function of the solute concentration in a solution. It is determined by the number of solute particles dissolved in a given amount of solvent. The more solute particles present, the lower (more negative) the osmotic potential. Water moves from regions of higher (less negative) water potential to regions of lower (more negative) water potential.

Hence, the correct answer is option 3) Both a and b

Also Read:

• MCQs on Osmotic Potential

• Facilitated Diffusion

• Symport, Antiport, Uniport

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