High School Biology: Transpiration Experiment

In science classes, students should be doing experiments.  Not just “cook book” experiments, but real inquiry.  These photos are from an experiment some of my high school biology students designed to investigate transpiration in pansies.

Photos downloaded June292015 003

One of the exciting things about student-designed experiments is how often students develop genuinely interesting ideas to test.  In this case, one of the questions they were asking was, “Does putting physical pressure on roots (by pressing the root balls with a large book) change transpiration rates relative to plants that are not pressed?”  In other words, from a biological point of view, how important is the pressure of overlying soil on roots?  It’s a good question, and one that I’d never heard before.

Photos downloaded June292015 004

In this case, the experiment suggested that roots under pressure may be less efficient than roots that are not under pressure (i.e., there was less transpiration).  However, there were some difficulties with the experimental design which makes these results less than compelling.  As a teacher, I’m happy that my students recognized these difficulties, acknowledged them, explained how they could have overcome them if they’d had more resources, and didn’t overestimate the meaning of their findings (but didn’t completely dismiss them, either).

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3 thoughts on “High School Biology: Transpiration Experiment

    1. Alas, no. One of the frustrating things about SAT-level biology is how much material there is to cover in a very limited amount of time. Lack of time means that we almost never have the luxury of extending an experiment, especially when it is a long-term one like this was.

      Liked by 1 person

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