Students have a choice about the accredited and approved degree they can undertake to complete step one of the training pathway in psychology. You can view the study pathways diagram. It is important that you complete a course that is accredited by the Australian Psychology Accreditation Council, referred to as APAC, otherwise you may not progress to step two on the training pathway.
This means that you have many options for the degree you need to complete such as a Bachelor of Psychology, Bachelor of Arts, Bachelor of Science and others, as long as they appear on the APAC website as being accredited.
Therefore the prerequisite subjects you need to complete during your senior years will depend upon your choice of degree. I recommend consulting your state tertiary course manual and speaking to your school careers advisor for more specific information about subject decisions.