Tracking active uptake of minerals by plant roots
Class exercise
This is a thinking exercise only, rather than a practical protocol, but provides a data set to analyse as described on the student sheet.
Lesson organisation
Hand out the 
student sheet with questions and answers (289 KB). Talk through the protocol. Allow students to work through the questions. The later questions are more demanding and some students may need more support.
Apparatus and Chemicals
For each group of students:
Copies of the student sheet
Graph paper
Pencil
Ruler
Health & Safety and Technical notes
Read our standard health & safety guidance
The rate of uptake of sulfate ions is faster in aerobic conditions, which suggests that the presence of oxygen improves the ability of the seedlings to take up sulfate ions. As oxygen is used in respiration (the process by which energy is made available) it is reasonable to suggest that the data support the hypothesis that mineral uptake by plants is an active process. However, the data for anaerobic conditions suggest that, in this experiment at least, diffusion can account for the uptake of some of the sulfate ions.
The half-life of radioactive sulfur is 88 days, and the course of this investigation is 4 hours. Therefore, although the data for sulfate uptake will be a slight underestimate – it is only slight.
Health & Safety checked, September 2009
Downloads
Download the student sheet Tracking active uptake of minerals by plant roots (289 KB) with questions and answers.