Light level may be varied using a voltage regulator control. The light level used in the experiment is monitored by a light sensor situated beneath the leaf chamber. Analog outputs from both the O 2 sensor and the light sensor are converted to digital signals by a Serial Box Interface. They are recorded and displayed to the screen using Data Logger data-acquisition software. The software is also used for subsequent data analysis.
Students can display raw data to screen, or plot any two data sets against each other.
For example, the graph below shows the raw data from an experiment in which the leaf chamber O 2 concentration is monitored as irradiance is gradually reduced. This derivative has been plotted against irradiance to generate a photosynthetic light response curve. It includes suggested variations to make experiments more, or less, challenging. We have used both the Photosynthesis and N 2 ase assay systems and find them robust and easy to use. An excellent feature is that the students can assemble the unit, get it working and then handle the data.