ISRO exam copies many questions from previous year GATE papers - when they copy they don't care for plagiarism and it is just CTRL+C, CTRL+V as most other exams in India (they have issue only when students copy).
So, look at previous year papers- 2013 ISRO paper is fully added here and rest will be added within next week. You can also download the full papers here.
Now, please don't make the mistake of studying only the previous year questions - because they seldom do repeat from already asked ISRO questions. Rather solve previous GATE papers and you can get a good amount of repetitions.
Good thing about ISRO exam is that they have good answer debate option and hence don't have to worry about ambiguous questions. Bad thing is their syllabus has some topics outside GATE.