Cambridge O Level Biology · Syllabus 5090 · Coordination and Response in Plants
Clinostat
What is Clinostat?
An apparatus that rotates a seedling slowly about a horizontal axis so that the direction of gravity relative to the organ changes continually. It is used as a control in gravitropism investigations: it does not remove gravity, but it prevents gravity from acting persistently from one direction relative to the plant.
This definition is part of the Coordination and Response in Plants chapter in Cambridge O Level Biology.
Common mistakes with Clinostat
- 13. “A clinostat removes gravity.” Why it is wrong: no laboratory apparatus removes gravity. Rotation changes the direction from which it acts relative to the organ, not whether it acts. SayA clinostat rotates the seedling slowly so that gravity does not act continuously from one direction relative to the organ, so no persistent one-sided stimulus is maintained.
Questions students ask about Clinostat
How do you investigate gravitropism?
Pin several germinating seeds horizontally against damp support inside a transparent container, mark the starting positions of the roots and shoots, and keep the container in darkness so that light cannot act as a second directional stimulus. Record the direction and angle of growth at intervals, using a slowly rotating clinostat as the control.
What does a clinostat do?
A clinostat rotates a seedling slowly so that the direction of gravity relative to the organ changes continually, preventing a persistent one-sided stimulus. It does not remove gravity, and it is not an anti-gravity machine; it is a control that allows stationary and rotated seedlings to be compared.