I hadn't gotten any other questions from my fiancés lab-mate so I thought I'd just tackle another one that stumps some parents into flat out lying.
"Where did fluffy go?" (assuming fluffy is a pet that has died)
As with the first answer, and I'm assuming most of my answers, Im going to use honesty and science as best I can to answer the question.
Well, fluffy is now (wherever fluffy physically is now), but she has died. Dying is something that happens when enough parts in your body stop working that every stops working all together. There are many things that can cause death.
Imagine your body like your favorite battery powered toy. It has many ways it could stop working too. It could fall and break enough important parts off it, that it would not work anymore. Just like your body, not all accidents will cause it to break all the way, sometimes it can still be fun with a piece or two missing. But once enough of its parts are missing, or broken, it cannot be played with anymore.
It could also run out of batteries. This can happen to your body if you don't feed it enough of the right food. Our bodies use food like your toys use batteries. If you do not eat enough food to make your body go, it can stop working (which we call dying).
Your toy can also stop working just through using it so much. If you play with a toy all day long, every day for enough days, it will eventually wear out and break. This also happens in our bodies. We call this dying from old age. Most peoples bodies cannot keep working for more than 80 or so years. Sometimes peoples bodies will last longer, sometimes shorter. This is determined by how well they take care of their bodies, and how well their bodies are built (which is determined by genes, which we already learned about) You can also make your toys last longer if you take care of them, so make sure to play nice with them :)
You may be thinking, well why can't we fix fluffy? Sometimes we can fix bodies. This is a very good question, and one that scientists are constantly looking at. Sometimes (in very rare instances) we actually can "fix" bodies that have died. The main difference between toys and bodies, are that we made toys, so we know exactly how all the parts work 100%. And we can make new parts very easily. With bodies, we cannot make new parts for everything just yet, and we are learning more and more everyday, but we are very far from knowing everything about how they work.
So while fluffy is now (wherever fluffy is physically) fluffy is not alive anymore, and we do not know enough right now to "fix" him/her.