Here is some information from Northwestern as an example as to whether or not Subject Tests may be required. You should check with each college on your list to see their requirements:
"While SAT Subject Tests are optional for most undergraduate applicants, scores from SAT Subject Tests are required for applicants to the Honors Program in Medical Education (HPME), the Integrated Science Program (ISP) and applicants who have been home-schooled.
Specific exam requirements:
HPME: Chemistry and Math Level 2
ISP: Chemistry, Physics and Math Level 2
Home-schooled: Math Level 1 or 2, plus two other SAT Subject Tests of the applicant's choice from different areas (i.e., not two science or two foreign language or two history, etc.)"
http://admissions.northwestern.edu/faqs/high-school-courses/index.html#reasoning-writing