system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Since plants do not have muscle fibers, how do they get flaccid when deprived of water and stiff again when watered?
gpt
Plant cells fill up with water when there's water around and lose water when there isn't.  You know how when you blow up a balloon, its skin is rigid and you can bounce it off of things, but when you let all the air out it's just floppy and useless?  Plant cells are basically like that, but they're filled with water instead.  They're rigid when they're full of water and flaccid when they aren't.