I use this article and the corresponding questions with my A.P. Biology students. The article (not included, but it can easily be found on the internet or by scanning the QR code provided on the questions), is a discussion paper from a journal called Biogeosciences Discussions. Not only will it help students learn about chemosynthesis, but it will also expose them to a scientific paper. I have students define key terms on the front of the worksheet before reading in order to help them understand the content better.
The answer key is included at the end of the document.
Corresponding article: http://www.biogeosciences-discuss.net/9/17037/2012/bgd-9-17037-2012-print.pdf