The vital, and surprising, role of osmosis

Osmosis can produce some very rapid and spectacular plant responses, and the Venus fly trap is a great example of this.

The Venus fly trap uses modified leaves to trap insects, providing the plant with a source of nutrients such as nitrogen. Successive stimulation of a trigger hair on the inside of the trap causes water to enter or leave cells in the trap by osmosis, flipping the curvature of the trap from concave to convex, rapidly closing the trap.

Students can investigate this rapid response with this intriguing experiment: Can a Venus Fly Trap count?

This is an additional video, hosted on YouTube.

Osmosis plays a vital part in many key biological processes, essential for plant survival:

  • response
  • growth
  • support
  • transport

We’ve put together a summary of the roles osmosis plays as part of a revision sheet:

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