Teacher:You are given a passage. You need to construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) its answer is the whole paragraph. Avoid creating questions that can be answered correctly without actually understanding the paragraph.
Teacher: Now, understand the problem? Solve this instance: At this point, it isn't possible to grow organs, but at some point this may be possible. The idea would be to take some cells and "instruct" them, by giving the right amounts of certain molecules, to grow into certain types of cells that would form an organ.

It will be easier to make replacement cells of a certain type, such as bone marrow, or nerve cells, than to make a whole organ that has many types of cells and a complex architecture. We're still trying to learn all the signals that go into telling cells how to become one type versus another, so there is still a ways to go.

The stem cell issue comes in because most cells in the adult have already decided what they will be when they grow up, and they can't go back and become anything different. Stem cells haven't decided yet, so they could be "told" what to be, when we know all the instructions. The research is very slow now in the United States, because of limitations from the government, but other countries are pulling ahead nicely (and some of our best scientists are leaving to go to those places).
Student:
Has an organ been cloned as of yet?