Eeeeyup though I'm still a student I live and work in a similar field so obviously I deal with the exact same issues. So to answer whether or not you should respond to these things, let me explain how I cope.
1) With the exception of peer reviewed journals do not read anything about biology on the internet.
If you need to know about it, you'll find out through more legit channels sooner or later.
2) Never "take on" more than one person at a time.
It's true there are no dumb questions, but it's also true that one idiot can ask more questions than a thousand sages can ever answer. I'm sure you're familiar with how much effort can go into disecting even one of these uninformed statements by one person. If so, you can probably also see the madness in dealing with more than one at a time.
3) Have an opinion.
Biology is the most controversial science in the world right now. What other field deals with such a laundrylist as GGO's, global warming, animal testing, creationism, habitat conservation, etc., etc...? As such you're bound to deal with highly opinionated people (well informed or otherwise) sooner or later. When that happens the best response is to state your well thought out opinion on the matter and walk away. Don't stick around trying to "win" the debate, noone has ever changed his/her mind after a single counter-argument. Unless they weren't that opinionated to begin with, but then they wouldn't have started the discussion in the first place.
4) Never start these discussions yourself, only respond when "challenged".
You can spend a lifetime sniping off every misconception you come across and still achieve no net result. Stick to the ones that matter instead. For example: if someone you care about is getting ripped off by a spirit healer or whatever. And even then tread carefully: being told you're wrong is not fun and noone will ever thank you for it, regardless of if you were right.
5) Have some empathy.
If you were born only a few short generations earlier you'd probably have a problem with woman voting. Would that have been your own fault? Hard to say right? Keep that idea in mind when dealing with anyone with an uninformed opinion. It's not about dragging them into the Glorious Light of Science, it's about gaining the respect you know your field deserves.
Hope it helps
