That is one of the best questions that I have seen. I can't speak for other Scienceline Answerers, but my guess is that we answer the questions in a similar way. It depends on how close the question is to what I know most about - in my case, my specialty is vertebrate fossils (long-dead animals with backbones) and specifically, I work on a group of reptiles that evolved with the earliest dinosaurs (sort of a distant cousin, you could say). So, if you ask me something about reptile fossils, including dinosaurs, I could probably give you an answer right off of the top of my head. I would probably still go to my collection of books to check a couple of answers.
If you ask me something less close to my specialty, I can usually give a general answer based on what I have learned from classes or reading on my own, but I would definitely check the facts either in my own books or in the library. I often look on the web for information, too. I guess what this means is that if you know where to look, you could be just as much of an "expert" as I am on the topics that I haven't specifically studied.

This is a good question because it gets at what being a scientist is about. Basically, scientists ask a lot of questions and try to answer some. It helps to know things because then you can usually ask more interesting questions. For example, say you had to write out a couple of questions to ask the new kid in your class. If you didn't know them at all, your questions might be pretty dull and you might not even care about the answers.
But what if you already knew that they had won a national music competition, or trained dogs to compete in agility work, or volunteered to help care for children with disabilities, or had been to Peru? Then you might have some really interesting questions that you wanted to know the answers to.
You don't always have to know a lot to ask good questions. If you pay attention to things and think about them, you come up with a lot of interesting questions to ask. Students ask me interesting questions all the time.
Because I have a lot of education in biology, it's easier for me to find answers to questions. Most of the time, I know part of the answer but might still try to look up interesting facts, pictures, or other things.
For example, last week a student wanted to know whether pandas were grouped with bears or raccoons. I knew that they were classified with bears last I heard. But I wanted to see if any new information had come up, so I did a quick internet search and found that DNA evidence confirmed they were bears. Because I already knew the scientific names of the raccoon and bear families, I was able to get right to some good sites and skip the thousands of sites selling panda mugs or telling me how to keep raccoons out of my trash. Knowing the words of science helps a lot.
It's also important to know the big ideas of science so you can quickly tell what's possible and what's not. For example, the movie "The Matrix" and its sequel are based on the idea that in some future or other reality, a society gets its energy by harvesting it from people. The laws of thermodynamics tell us that energy can't just come from nowhere and that every time you change one form of energy to another, you lose some of it. Energy in the form of food would have to be fed to the humans. The humans would use a lot of it, so whoever was trying to get energy this way would only get about 20% of the energy they'd get by burning the food itself. So that idea does not make sense.
I doubt anyone is going to these movies to learn science, but every day people have to decide whether a product can do what it claims to do and it won't be long before you're voting. The more you know, the more you can make up your own mind without having to just trust what other people tell you.
So scientists have to know a lot so they can ask good questions and come up with explanations. They also have to know a lot so that they can speak the language of science and tell good explanations from bad ones. But no one can ever know everything about science. There's always more to learn. That's part of the fun.

I've answered a few questions before for Scienceline. I only attempt to respond to a question if I'm pretty sure that I already know the answer, or at least most of the answer. Often, I will look up some things to make sure I get the details right, and sometimes I'll look up some related topics of interest so I can include them in my response.
You students come up with some great questions, and most of them I actually don't know how to answer off the top of my head. I always leave those questions for somebody else to handle.

I don't remember whether I have answered your questions, but I can say this. Most of the time, I know the answers, but I do often have to look up details, usually from some books I have.
The questions that we answer in Scienceline usually require quite a lot of thinking, even though they may be posed to look simple.

I only answer the questions that I know something about. I do, however, try to look up some place on the Internet, and I put the address in my reply, so that the student can get more information.It's great that you ask so many questions - keep it up!

Sometimes I know the answers, like today. But most times I go to one of my many books, or read some science articles in a journal or use this wonderful resource that we call Internet in order to get all the information I need so that my answer is as good as I am capable of putting together. It is sincerely my opinion, that in today's world, it is not so important how much you know as it is how good you are at digging the information you need and transforming it into knowledge, that is, information working to solve a problem. Keep your curiosity alive and keep all those wonderful questions coming to us.!

Some answerers sign up to answer any questions that are sent to them and some (like me) just answer questions that they want to answer. So I choose questions to answer that I happen to already know! Sometimes I look up a number in a book I have, but not very much. If I had to answer every question, though, I'd definitely have to look up a lot of them!

Sometimes we know them and sometimes we do not but part of being well educated is knowing where to find the information you do not already know. Kind of like you using Scienceline.

I'm glad you ask us lots of questions. Usually I look up the answers at www.google.com like I recommend to you, but yours is the 4th question I've answered today without checking google.com. I could have gotten more information about one of the questions by checking google.com, but I knew enough to answer it without searching, and I didn't feel like searching today. I do lots of searching on google.com for lots of things in my work and my play.