Ah ha ha ha ha ha ha ha ha. Oh, sorry, you were serious. Our mistake.
You’re right, yeast are living, though they are neither animals nor plants but actually single-celled fungi. We know it can be confusing to have more than two categories of living things, so we’re going to give you a little insight into yeast to see if we can make it stick.
There are around 1,500 species of yeast, and these microscopic cells play many roles. In nature, they grow on plants and in the soil, and act as natural biological decomposers. In beer, yeast turns the sugar to alcohol and gives it that unmistakable beery flavor. In the human body, yeast can make a person itchy and burny in the down-below-department, which some might consider a failing on the part of yeast.
Anyway, we digress. Whatever its role, the important bit to remember is that yeast have no central nervous system – no nerve cells, brain or spinal cord – which transmits sensory information and coordinates appropriate actions.
Without a central nervous system, yeast (and plants, Phil, before you pop back up with a supplementary question), cannot feel pain.
So, yes yeast is alive. No, it is not an animal. Yes, it is vegan. We hope that clears it up for you.