There is this book 6 Year Series STPM Biology
by Pearson Longman which has past years collections, which is 1999-2004. You can check it out here
. (Answers already in the book)
(Oxford Fajar) Volume 1 has STPM 2007 paper. (Answers already in the book)
(Oxford Fajar) Volume 2 has STPM 2008 paper. (Answers are on their website. Check them out here
Actually, in ACE Ahead
series there are past year 2005-2007 questions at the end of every chapter, also with complete suggested answers.
For Pengajian Am (Kertas 1 & 2), there is this Kertas Peperiksaan STPM Sebenar
series which has STPM 2005-2008 papers with suggested answers. Check it out here
. This is really useful =)
Now Oxford Fajar seems to be the official publisher for STPM past year paper since 2005, so when you wanna look for past years, look out for Oxford Fajar books.
For STPM 2005 and 2006, you try yo get from your teacher or look for it in your school library? I am not sure about the library in your school but the one in my school has all the past year papers. =)
By the way, I don't think you need to do so many years of past year papers as some of the syllabi has altered. So, personally I do not recommend the Pearson Longman book above, which is not worth the money also - RM26.90. And the publisher just change the book cover every year, while the contents are all the same, so basically you can borrow from your seniors or get a photostated /'pirated' copy which will cost you no more than RM10.00.