I want to know what are some typical experiments performed in the course of biology education (or possibly in applied biology education e.g. agricutlure education) to prove to the students (or have them prove to themselves) the autocatalytic role that ethylene plays in ripening. I'm interested in both how ethylene production by plants might be demonstrated/measured as well as the demonstration of the role of ethylene on ripening.

I'm aware of some historical experiments e.g. that of Gane (1934). Is it commonly repeated in biology labs in an educational context today? Or is something else used?

I found a lab manual aimed at Indian "class XII" (I guess that's the terminal year in high-school over there); the experiments aren't well detailed but they suggest keeping a sample in open and one packed in polyethylene, or treating one with ethylene. These aren't exactly quantitative though: no suggestions for measuring anything but by eyeballing/tasting. I guess that's the best on can do with limited resources. I'd like to know about college-level experiments, if there are any.

I also know how ethylene is measured in industrial/pro-lab settings:

Ethylene can be measured successfully with a portable gas chromatograph fitted with a photo ionisation detector capable of measuring ethylene to a concentration below 0.01 uL/L. EASI-1 uses a proprietary ‘nanoporous gold sensor technology’ for “accurate real-time measurement of ethylene gas concentrations”. This is licensed from Fluid Analytics in USA, which offers a claimed sensitivity to ethylene in the air at levels as low as 10 ppb.

There also exist industrial scrubbers for ethylene so the air concentration can be reduced. I don't know if either of these are commonly available on college campuses though, even in biotech or agriculture departments.

(N.B.: I don't care about proving the effect in the kitchen, which is the topic of a question on Skeptics.)

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    $\begingroup$ One way (I don't know how easy it is to get hold of the compounds in your locality) would be to have three sealed containers containing apples, one in standard conditions, one in elevated ethylene, and one with 1-methylcyclopropene which competitively binds the ethylene receptor, and observe the differences in ripening rate. $\endgroup$
    – NatWH
    Aug 27, 2018 at 23:26
  • $\begingroup$ As titled and phrased, this is a question that only a professional teacher could answer. Is this your intent or are you really asking for ideas of nice, compact demonstrations that could be done in a classroom? $\endgroup$
    – user24965
    Aug 28, 2018 at 3:01
  • $\begingroup$ @JimYoung: I want to know how it's done (if it is) in existing education, not for radom ideas how it could be done. And it's not just that a "professional teacher could answer". Lab manuals etc. anyone can read. $\endgroup$ Aug 28, 2018 at 11:41
  • $\begingroup$ This is a Biology list, not an education list. So it's OK to ask how it was shown that ethylene has a role in ripening — although we'd expect you to show that you'd tried to find the answer yourself — but I think it's off-topic to ask how to do it in the constrained circumstances of a teaching course. $\endgroup$
    – David
    Aug 28, 2018 at 12:25
  • $\begingroup$ @David: really? Let me ask on meta here. Actually, it was asked already, and you seem to be wrong: biology.meta.stackexchange.com/questions/3162/… "questions that ask for ways and methods to teach specific biological concepts or techniques (lab or field) should be on-topic." (that's the only answer) Also "All questions asking for this type of advice should be narrowly defined, so that the scope of possible answers isn't too wide." Not asking about hypothetical but only about actually used methods seems to satisfy that well. $\endgroup$ Aug 28, 2018 at 12:26


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