Name: plant cells and water balance
Uploaded: 2025-05-22T09:05:46.000Z
Duration: 1 min 20 s
Channel: JoVE

Tonicity describes how the extracellular solute concentration changes plant cell volume by making the cell lose or gain water. There are three possible conditions.
In a hypotonic environment, solute concentration outside the cell is lower than inside, causing water to enter the cell via osmosis.
Water influx makes the plasma membrane push against the cell wall creating turgor pressure.
The rigid cell wall prevents the cell from bursting by limiting the expansion of the plasma membrane.
The resulting stiffening or turgidity allows the plants to remain upright.
When plants cannot uptake water, the extracellular surroundings have higher solute concentrations or hypertonicity, causing water to leave the cell.
As a result, vacuoles decrease in size, and the plasma membrane detaches from the cell wall as the cytoplasm shrinks. Such plasmolysis explains why plants wilt.
In isotonic environments, solute concentrations outside and inside the cell are equal. So, there is no net movement of water. The cells become flaccid, and the plant starts to droop.

tonicity in plants

Tonicity in Plants

Plant cells maintain appropriate osmotic balance in extreme conditions. For instance, plants in dry environments store water in vacuoles, limit the opening of their stoma, and have thick, waxy cuticles to prevent unnecessary water loss. Some species of plants that live in salty environments store salt in their roots. As a result, water osmosis occurs in the root from the surrounding soil.
Tonicity
Tonicity describes the capacity of a cell to lose or gain water depending on the solute concentration outside. Organisms such as plants, fungi, bacteria, and protists, have cell walls surrounding the plasma membrane. Three possible scenarios alter the volume of a cell: hypertonicity, hypotonicity, and isotonicity.
Hypotonic environment
In hypotonic environments, there is a higher concentration of solutes inside plant cells than outside. Water enters the cell via osmosis and causes it to swell. Because the cell wall limits the expanding plasma membrane, the cell does not lyse. By limiting expansion, the cell wall allows cells to become turgid, resulting in the stiffening of plants.
Plant cytoplasm is always slightly hypertonic to the cellular environment, and water will always enter a cell if water is available. The force generated when an influx of water causes the plasma membrane to push against the cell wall is called turgor pressure. Turgor pressure keeps non-woody plants upright.
Hypertonic Environments
Conversely, the extracellular fluid becomes hypertonic in a dry climate, causing water to leave the cell through osmosis. In this condition, the cell cannot shrink because the cell wall is not flexible. As a result, vacuoles decrease in size the cell membrane detaches from the wall and constricts the cytoplasm. This process is called plasmolysis. Thus, plants lose turgor pressure and wilt.

Plant cells maintain appropriate osmotic balance in extreme conditions. For instance, plants in dry environments store water in vacuoles, limit the ...

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JoVE Core

Cell Biology

Unit 1

Plant Cell Structure and Organization

KEY TERMS AND CONCEPTS

plant cells and water balance

Plant cells use tonicity to manage water balance in changing environments. Tonicity is the ability of a cell to gain or lose water based on the solute concentration outside the cell. Many organisms with cell walls, including plants, fungi, bacteria, and protists, rely on this balance to protect cell shape and function.

Plants also use several features to reduce water loss in dry conditions. They can store water in vacuoles, close their stoma more often, and develop thick, waxy cuticles. Some plants that live in salty environments store salt in their roots, which affects how water moves into the root from the surrounding soil.

In a hypotonic environment, the solute concentration is higher inside the plant cell than outside. Water moves into the cell by osmosis, and the cell swells. The cell wall keeps the plasma membrane from bursting. This pressure makes the cell turgid, which helps stiffen the plant.

Plant cytoplasm is usually slightly hypertonic to the surrounding environment. That means water will enter the cell whenever it is available. The force created by this water flow is called turgor pressure. Turgor pressure helps non-woody plants stay upright.

In a hypertonic environment, the outside fluid has a higher solute concentration, such as during dry weather. Water leaves the cell by osmosis. The cell wall cannot shrink, so the vacuole becomes smaller, the cell membrane pulls away from the wall, and the cytoplasm tightens. This process is called plasmolysis, and it causes plants to lose turgor pressure and wilt.

Plant Cells and Water Balance

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Plant cells use tonicity to manage water balance in changing environments. Tonicity is the ability of a cell to gain or lose water based on the solute concentration outside the cell. Many organisms with cell walls, including plants, fungi, bacteria, and protists, rely on this balance to protect cell shape and function. Plants also use several features to reduce water loss in dry conditions. They can store water in vacuoles, close their stoma more often, and develop thick, waxy cuticles. Some...

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key terms and concepts

Learn how plant cells use tonicity, osmosis, turgor pressure, and plasmolysis to stay upright, manage water, and respond to dry or salty conditions.

Plant Cells and Water Balance | JoVE K12

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JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

Plant Cells and Water Balance

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