In fact, here’s the usual sequence:

• 1st: Chem 1A/L, Math 1/10A
• 2nd: Bio 1B, Math 1/10B, Chem 3A/L (or over summer)
• 3rd:  Bio 1A/L or Chem 3B/L, Physics 8A
• 4th: The other lab class, Physics 8B

While 2nd semester is potentially two lab classes, it’s the most benevolent combo. Also, having Bio 1A/L done early means you can probably start on Bio upper Divs your fourth semester if you’re ambitious.

If this still does not convince you to take Chem instead of Bio your first semester, read ahead.

 “Should I take Bio 1A/L instead of Chem 1A/L my first semester?”

• Bio 1A/L cannot be taken concurrently with Chem 1A/L (or Chem 4A).
• Chem 1A/L (or Chem 4A) is a prerequisite.

• 1-2 Semesters of O-Chem are recommended (3A-B/L or 112A-B).
• They actually check and drop you.

Short answer is: Unless you’ve taken Chem 1A the previous summer, it’s not happening. Even then, you should focus on working through the Chem reqs.

“Should I take Bio 1B instead of Chem 1A/L my first semester?”

This one sounds more logical for those dead-set on taking Bio the first semester, but here are the unintended consequences.

Assuming you’ve only taken Bio 1B your first semester, you’ll be taking Chem 1A/L and Physics 8A the following semester, followed by three possible tracks:

3rd Semester:
1)    Chem 3A/L + Physics 8B

2)     Bio 1A/L + Physics 8B

3)    Chem 3A/L + Bio 1A/L

4th Semester:
1)    Chem 3B/L + Bio 1A/L

2)    Chem 3A/L; take Chem 3B/L next semester

3)    Chem 3B/L + Physics 8B

Summary:

• Track 1: Two Lab Rigorous Classes 4th Semester
• Track 2: Finish Semester Late
• Track 3: Two Lab Rigorous Classes 3rd Semester

By adding in a semester of summer school of either Chem 3A, Chem 3B or Bio 1A after your freshman or sophomore year, you should be able to correct for both two lab classes and finishing late, though. As per Victoria Lo’s advice, you can also talk to your major department and move Physics 8A/8B ahead a year. For Pre-Med, this would mean taking the MCAT a year late and potentially taking a gap year (talk to current Pre-Meds about this).

So take only Bio 1B your first semester if:

• You’re fine with summer school
• You’re fine with finishing late
• You’re fine with taking 2 lab classes in the same semester
• You’re fine with placing Physics 8A/8B off to Junior/Senior year and if you’re Pre-Med, taking the MCAT late and potentially having a gap year.

*The following scenarios do not take into account the following combinations:

• Chem 1A/L & Bio 1B first semester (Two Lab-Rigorous Classes)
• Physics, Chem & Bio the same semester
• The fact that you’ll be doing Math somewhere in there as well. Hope this answered questions & good luck!