1. Read the information below about stem cells:

It may be possible to treat some human diseases, such as Parkinson’s and diabetes, with stem cells in the future.

Human early embryos produced in vitro are a source of stem cells.

The use of embryonic stem cells to treat human disease is new and patient trials have already begun.

Another source of stem cells is adult bone marrow.

The operation for collecting these cells is simple but it can be painful. It is already possible to use adult stem cells to treat certain blood diseases.

There is also hope that adult stem cells from bone marrow can also be used to treat other diseases such as heart disease; such trials have already begun.

Explain how an embryonic stem cell differs from an adult stem cell.