Computer Science and Biotechnology are two different streams. Computers Sciences more of falls under IT while Biotechnology falls under Life sciences. So there is no connection between them. If you complete Biotechnology and want to do your PG, you can only study in those subjects that you studied in your B.Sc Curriculum like English, Biotechnology, etc. Few recommended courses can be MBA in Agricultural Management, Pharmaceuticals, etc. For M.Sc you can try Medical Biotechnology, Molecular Biology, Veterinary Virology, etc. But not computer sciences.