IB Environmental people:
The answers for the May 2011 Exam Paper 1 and Paper 2 (which you got in class) are NOT posted. Apparently, IB has not released the solutions yet. The same is for the May 2010 [ES&S SL P1 May 2010]; only the questions are posted below.
HOWEVER, there are solutions for:
Specimen Papers that IB has released as examples for the exam. The questions AND their answers are posted as [Environmental Systems and Societies Specimen papers and Markschemes] below.
And a whole bunch of Exams and their answers from past years for you to study and enjoy in your pursuit of knowledge. Woo.