How is the SAT Subject Test set up?

Test Preparation SAT Subject Test Preparation
1

On test day, do you receive a packet with all subject tests?

Also, how does the Biology test work? Do you take either the molecular or ecological, or both?

2

Yes, you’ll receive a packet/book with them all.

For Bio, you pick one (since both have a shared core of questions you can’t take them both on the same day). There are 60 shared questions you’ll take for both E and M, and then 20 specific to E/M (you only pick one set of these 20, i.e. either 61-80 or 81-100).