Three-way Taps (AQA A Level Biology)

Apparatus & Techniques: Three-way Taps

• Three-way taps can be used in conjunction with potometers and respirometers

• They allow for repeat readings to be taken easily, eliminating the need for the apparatus to be reassembled each time

• Potometers:

  • When used with a water reservoir they allow for the air bubble to be returned to the start of the tube by allowing water to enter the system

• Respirometers:

  • The three-way tap can be used with a syringe to push the bead of coloured liquid back to the start

The image above shows a respirometer set up with a three-way tap. The three-way tap allows for the drop of coloured liquid to be returned to the start of the ruler after each repeat of the experiment.