system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5, how do selective herbicides such as broadleaf weed killer work? Why do they only kill certain things?
gpt
By targeting something that only that species or group of species have.

Because they are broadleaf, that means they are all related. Much like humans, chimps, gorilla's all share many characteristics because we all primates.

So we find something that all broadleaf has in common, that other plants don't and target that.

It could be a chemical that inhibits their growth, prevents cell division, something like that.

Anti biotics work in the same way. You take a drug that only hurts bacteria and not you, because it targets things only bacteria have.