This experiment allows you to see protozoa, tiny-single celled organisms, in your compound microscope. While I can go in my backyard and find a lot of interesting pond scum and dead insects, I realize that not everybody has a thriving ecosystem on hand, especially if you live in a city.
I am going to show you how to grow a protozoa habitat that you can keep in a window for months (or longer!) using a couple of simple ingredients.
Once you have a protist farm is up and running, you’ll be able to view a sample with your compound microscope. If you don’t know how to prepare a wet mount or a heat fix, you’ll want to review the microscope lessons here.
Protozoa are protists with animal-like behaviors. Protists live in almost any liquid water environment. Some protists are vital to the ecosystem while others are deadly.
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The nasty smell is common and comes from the yeast. If you used tap water, did you let it sit for at least 24 hours to let the chlorine escape? If not, the protozoa may not have survived.
Also, slide preparation is a huge factor. I recommend reviewing the microchip lessons on preparing a wet mount or heat fix. The link is provided in the description above.
Hello, we did your experiment and got a pretty nasty smell come from it. We let it sit for at least 2 weeks. However when we looked at it we couldnāt find anything that looked like it was moving. We even tried adding iodine to it. Do you have any suggestions? Thanks!
Just a small spoonful… it’s not really that important. You don’t even need to add it (this just makes sure you’ll get something good to look at on your slide).
how much yeast do you put in the glass
Not dangerous… just organic! š IF it starts to smell, then you know you’ve got some good stuff in there to look at. Use gloves and tweezers to move your samples to the microscope slide and see what you’ve got!
Our culture has only been growing for 4 days and it stinks really bad!!! We live in a warm climate and it is summer now. Did we make something dangerous?
Yes, you should still have critters on it to see with your microscope, especially if you are keeping them in a warm place for two weeks. The amount of oxygen in the jar will not get used up (not even close!) in that time, but if you’re concerned, simply open the lid and waft in some fresh air every couple of days.
The (Cu(OH)2) [a plus-2 ion and a negative-1 ion] precipitates at the bottom. The alligator clips have oxidized due to (my guess) lots of copper. Iām sure the brown color is due to an iodine compound, but since Iodine can exist in up to 5 different oxidation states and the nature of the valence state would also depend on the type of electrolytic oxidation occurring, it would require isolation and analysis of the compound. This one isn’t easy to answer, however if you loot at the electrolysis of NaCl solution with Copper Electrodes here you’ll notice that the experiment is familiar: https://www.youtube.com/watch?v=1Uwy0FU4wgo
I am starting the experiment now, with grass I pulled from the backyard. There was frost on it. Will the grass still be a good source of protozoa? And, how will the protozoa get oxygen if I close the jar with a lid? do I have to airate from time to time?
Many thanks for your help,
Ilinca (6th grade)
Be aware that the protozoa smells really bad! We took our jar of protozoa outside because the room that we were working in smelled bad. Super cool to look at but smells bad!
Or even simpler – just add grass to a cup of water and let it sit in the sun.
When adding the yeast, do we need to make sure the temp of the water is 110 degrees? Do we need to add sugar for the yeast? Or is it as simple as adding yeast from the packet into the water with the grass?
Thanks.
i think its interesting that we get to use yeast..:)
wow thats super interesting:-)
those are such cool protozoa
It’s possible your sample on the slide didn’t have any living critters, or that things were out of focus. Were you able to view the yeast culture? With and without iodine?
Hello. My kids and I followed the procedure for growing protozoa. But could not identify anything under the microscope. It just looked green. We made a slide with iodine and one without to see if that affected our results. Our sample had been growing for about 2 weeks. What are we missing? Thanks for your help.
You can certainly use fresh grass if you have it, but since it dies so quickly I suggested dead grass. The yeast provides the right environment for the protozoa to thrive in. If you send along a photo I can have my team take a peek and let you know what they can identify.
Aurora
Hi Aurora,
I was doing this experiment and I was wondering why must we use yeast and dead grass? Why not yeast and fresh grass? What does yeast do? I saw some tiny stick-like microorganisms(?) and what are they?
Thanks~
-Dayini š