Experiments for High School Students

[nautica]

I am needing to design some experiments for High School Students to explain Osmoregulation without harming the organism or experiments concerning excretory organs or systems.

Does anybody have any ideas or references I could turn to?

Thanks
Nautica

 

[nautica]

^^^^^^^^^^^^^^^^^^^^^^^^^^

 

[Moonbear]

You could try a urinalysis lab, like the one described at this site:

http://faculty.washington.edu/kepeter/119/labs/urinalysis-lab.htm#experiments

From the description, they use fake urine that's "spiked" to represent different pathologies. I don't think you should allow high school students to test their own urine, too much risk of contamination, though I've done labs like that in college level physiology courses (things like testing urine before and after consuming a large quantity of water or salt tablets to show how specific gravity changes). I don't know how the fake urine is prepared, but you could probably contact the course coordinator there and find out more information.

 

[nautica]

Thanks,

This is for a guy in my physiology class that is graduating this fall. He will be teaching high school biology and looking for some good ideas. We had thought about the urine thing, but like you said there are problems with that.

How about animal testing (safe animal testing)? I am afraid that one is going to be difficult to figure out.

Thanks
Nautica

 

[Moonbear]

Nothing comes to mind that would be useful from the perspective of using animals for this purpose. Usually the only high school lab that is associated with the excretory system is dissection to identify the excretory organs, which isn't really very exciting and doesn't teach anything about function, just structure. I guess most high school curricula just assume that kids know what pee and poop is and leave it at that. I'm trying to think if there are any species that are easily obtainable where something about osmoregulation would be unique, obvious to the observer, and changes are naturally experienced by the animal and won't harm it. Like a fish that can survive in fresh or brackish (mixed salt and fresh) water...they exist, but I'm not sure there would be anything outwardly apparent about their adjustment to different water, or that you could switch the type of water that rapidly without killing them.

I'm also trying to think if there would be an easy way to build a model of something like nephrons in the kidney...

oh...hmm...here's something...osmoregulation is all about diffusion and then pumps working against diffusion (in a very simplified way of thinking), so what about some demonstrations of food dyes diffusing across a membrane (I'm thinking something like a container filled with water, a paper towel or some other type of "membrane" between the two sides, and add droplets of food dye to one side and see how it gets through the pores of the membrane to the other side.

The other thing you can do is use a potato, take chunks of the potato, weigh them, place them in different solutions...hypertonic, hypotonic, isotonic (salt water works fine to create these...or plain water for hypotonic)...let the potato sit a while, then remove it, describe how it looks, and weigh it again...in theory at least, the potato should shrivel in hypertonic solution (water leaves into the surrounding solution) and plump up in hypotonic solution. Whether this change would be enough to measure, you might want to play with and find out (might depend on the size chunk you use if it becomes measurable). I remember doing something similar to this in high school...vaguely. I think we also used food dye in some water with potato chunks of different surface areas to see how far the dye penetrated, but I'm not sure that's as useful other than demonstrating general principles of diffusion.