Hypertonic Hypotonic Isotonic Diagram

All 13 labels on the diagram

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Red blood cell 8

Hypertonic solution More solute outside the cell than inside. Water leaves the cell and it shrinks.
Isotonic solution The same solute level outside and inside. Water goes in and out at the same rate.
Hypotonic solution Less solute outside the cell than inside. Water enters the cell and it swells.
Crenated cell A red blood cell that has lost water. It shrinks and its surface becomes notched.
Normal cell A red blood cell at its usual size. Water in and water out are balanced.
Swollen cell A red blood cell that has taken in water. If it bursts, that is called lysis.
Water moving out The net flow of water out of the cell. Water moves toward the higher solute level.
Water moving in The net flow of water into a cell. Inside, the solute level is higher.

Plant cell 5

Plasmolyzed cell A plant cell that has lost water. Its membrane peels off the cell wall.
Flaccid cell A plant cell that is limp, not firm. Its inside does not press on the wall.
Turgid cell A plant cell full of water and firm. Its inside presses hard against the wall.
Cell wall The rigid outer layer of a plant cell. It keeps the cell from bursting.
Central vacuole The large sac of water in a plant cell. It swells as water comes in.

How this list was compiled: Every name checked on 2026-10-01 and kept only where two independent sources use it. (1) Wikipedia, text only: Tonicity, https://en.wikipedia.org/wiki/Tonicity ; Plasmolysis; Turgor pressure; Crenation; Cytolysis. (2) The American Heritage Dictionary of the English Language, fifth edition, https://www.ahdictionary.com/ : hypertonic, hypotonic, isotonic, osmosis, crenation, plasmolysis, turgor, turgid, flaccid, hemolysis, cell wall, vacuole. The plan named two OpenStax books as its checking source; they were not read (the site has an open question about that source), so these two stand in. Licence: own work

The drawing: Drawn for this site on 2026-10-01 from plain geometry; nothing traced. Licence: own work

How it works

Tonicity compares the solute outside a cell with the solute inside. Water moves toward the side with more solute. The dots are solute: count them round each cell, then see what the cell does.

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A red blood cell has no wall to hold it

In a hypertonic solution water leaves, and the cell shrinks to a notched shape called crenated. In an isotonic solution it keeps its size. In a hypotonic solution water pours in, and the cell swells until it can burst.

A plant cell has a wall, so it cannot burst

In a hypertonic solution the membrane pulls away from the wall: the cell is plasmolyzed. In an isotonic solution it is flaccid, or limp. In a hypotonic solution the central vacuole fills and presses outward, the wall pushes back, and the cell is turgid.

Hyper means more and hypo means less: both describe the solute outside the cell.
Water follows solute. Find the side with more dots and point the arrow there.

Questions and answers

What is the difference between hypertonic, hypotonic and isotonic?

A hypertonic solution has more solute than the inside of the cell, a hypotonic solution has less, and an isotonic solution has the same. Water moves out of a cell in a hypertonic solution and into a cell in a hypotonic one.

What happens to a red blood cell in a hypertonic solution?

Water leaves the cell by osmosis. The cell shrinks and its surface becomes notched, which is called crenation. In a hypotonic solution the opposite happens: the cell swells and may burst.

What happens to a plant cell in a hypotonic solution?

Water enters and the central vacuole swells. It pushes the membrane against the cell wall, and the wall pushes back. That push is turgor pressure. The cell becomes turgid, or firm, and the wall keeps it from bursting.

What is plasmolysis?

Plasmolysis is what happens to a plant cell in a hypertonic solution. The cell loses water, and the living part inside shrinks and pulls away from the cell wall. The wall itself keeps its shape.