Prerequisite Planning Errors That Delay or Block Your Med Applications

You are seven semesters into college, MCAT scheduled, personal statement half drafted. You open a few medical school websites “just to double-check” requirements. Then your stomach drops.

Your dream state school requires a full year of biology with lab. You took one semester with lab and one semester in a compressed summer course without lab. Another school insists on two semesters of English or writing-intensive courses. You have one. A third demands biochemistry completed before matriculation, but the only section left at your university conflicts with your MCAT prep course.

This is how strong applicants get delayed an entire cycle. Not because of GPA. Not because of MCAT. Because of quiet, boring, fine-print prerequisite planning errors that nobody warned them about.

You are here to avoid becoming that person.

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1. Treating “Typical Prereqs” as Universal Requirements

The most costly mistake: assuming “standard med school prerequisites” actually exist.

Many premeds follow an informal list they hear during freshman orientation:

• 1 year of biology with lab
• 1 year of general chemistry with lab
• 1 year of organic chemistry with lab
• 1 year of physics with lab
• 1 year of English

That list is incomplete for a lot of schools.

Common additions that catch students off guard:

• Biochemistry (increasingly required, not just recommended)
• Statistics or biostatistics
• Psychology and/or sociology
• Calculus or “college-level math”
• Upper-division biology (e.g., genetics, cell biology)
• Diversity / ethics / humanities courses with specific designations

The mistake is assuming “if my pre-health office told me this list, then medical schools must all accept it.”

They do not.

Example scenario:

A student applying broadly discovers late that:

• UC Davis and UC San Diego strongly expect biochemistry
• Some Texas schools want statistics explicitly listed
• Certain osteopathic schools want 6 credits of English composition / literature, not “writing-intensive in any subject”

By the time they realize this, course registration is nearly closed, financial aid is set, and trying to cram missing prereqs derails their schedule and MCAT prep.

How to avoid this:

Do not plan from a generic list. Instead:

1. Identify a preliminary target list of 15–20 schools by end of freshman year (or at the latest, early sophomore year). Including:

   • Your state schools
   • Several private schools in different regions
   • At least a few DO schools if you will apply DO

2. Create a prerequisite comparison spreadsheet:

   • Rows = courses (Bio I, Bio II, Biochem, Stats, Psych, etc.)
   • Columns = schools
   • Color code: Required / Recommended / Not listed

3. Update it once a year because schools change requirements.

You are not “locking in” your school list as a freshman. You are reverse-engineering prerequisites from real possibilities instead of fiction.

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2. Misjudging What “Counts” as a Prerequisite Course

The second trap: assuming any course with “biology” or “English” in the title automatically counts.

Medical schools can be surprisingly strict about course classification. The most common miscalculations:

• Taking AP/IB credit and assuming it universally satisfies requirements
• Using online-only lab sciences when a school specifies “in-person lab required”
• Substituting interdisciplinary or special topics courses for core prerequisites
• Relying on pass/fail for key prereqs where schools want letter grades
• Counting remedial or developmental courses (e.g., “Intro to College Writing”) as the English requirement

AP/IB credit failure example:

A student enters with AP credit for General Chemistry I and II, skips straight to organic chemistry, and graduates with:

• Organic Chemistry I & II with lab
• Biochemistry
• No actual college-level general chemistry courses

Several MD schools either:

• Do not accept AP for prerequisites
• Accept AP only if supplemented with higher-level coursework in the same discipline

The student assumed “it is all chemistry, so I am fine.” They are not fine for those particular schools.

Online and community college pitfalls:

Common issues:

• Taking Organic Chemistry I at a 4-year institution, then Organic II online over the summer at a different school. Some schools explicitly state they prefer (or require) all sequence courses at one institution and with labs in-person.
• Completing physics at a community college after taking everything else at a highly selective university. Some admissions offices will not reject you for this alone, but it may raise questions, and some have written or unwritten preferences.

How to avoid this:

1. Read wording carefully, not just the headlines:

   • “Must be completed with in-person lab”
   • “No online lab accepted”
   • “AP credit accepted if followed by higher-level coursework in same department”
   • “Remedial courses do not satisfy this requirement”

2. Confirm ambiguous courses:

   • If you plan to use a “Writing in the Sciences” or “Technical Writing” course for English, email a few schools with the syllabus and ask if it satisfies their English requirement.
   • Ask whether “Statistics for Psychology” counts as statistics.

3. Do not rely on assumptions from older students. Policies change. What worked in 2018 may fail in 2026.

If a single prerequisite appears borderline (online, AP, or unconventional course title), assume it may be questioned and plan a backup solution.

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3. Poor Timing: Taking Prereqs Too Late or in Problematic Clusters

Planning errors do not just involve what you take. When you take it can delay or derail your application.

Common timing mistakes:

• Taking a required course after you plan to submit your primary application, when a school insists courses be completed before application rather than before matriculation.
• Scheduling biochemistry or physiology during the same semester as the MCAT, leading to weaker performance in both.
• Loading multiple lab-heavy courses in one semester, tanking GPA.
• Leaving a full-year sequence (like physics) half-finished when you submit, making some schools hesitant.

Example timeline problem:

You plan to apply in June after junior year:

• Fall junior: Organic II, Physics I
• Spring junior: Physics II, Biochemistry

You submit AMCAS in June having just finished Physics II and Biochem. Many schools will accept this plan, but a subset want certain prerequisites completed before application or want long-standing grades to judge science competency. If your grades are not yet posted, it may weaken your file or technically violate requirements.

The more serious issue: If your biochemistry course content has not been covered when you take the MCAT in April, you will struggle on key sections.

Dangerous course clustering:

Trying to “get it all done” often yields:

• Organic Chemistry I
• Physics I
• Cell Biology
• Genetics

Plus labs for all. That is a recipe for burnout and grade damage. A B– average in that overloaded semester can drop your science GPA enough to trigger screening cutoffs.

How to avoid this:

1. Map a 4-year prerequisite timeline on paper by early sophomore year:

   • Mark when each sequence will run (e.g., Physics I in fall, II in spring).
   • Place heavy lab courses in different semesters where possible.
   • Mark your intended MCAT test date and ensure biochem, psych, and soc are completed or in progress beforehand.

2. Clarify each school’s stance:

   • Some say “prerequisites must be completed before matriculation.”
   • Others say “before application” or strongly prefer a complete academic record.

3. Build in one buffer semester:

   • Leave space junior or senior year for a makeup course if a class is cancelled, you withdraw, or a grade is poor enough to warrant a retake.

If your timeline requires you to take three or more lab sciences while studying for the MCAT, you are planning for trouble.

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4. Ignoring School-Specific Oddities and Fine Print

Not all prerequisites are simple semester counts. Quiet landmines hide in the details.

Subtle traps you might overlook:

• Semester vs. quarter equivalents not lining up as you think
• Requirements for “upper-division” coursework, not just any biology
• Minimum grade thresholds in each prerequisite (B– or better)
• Requirements that certain courses be taken post-baccalaureate if your original coursework is very old
• Restrictions on where courses are taken (e.g., “must be at an accredited U.S. or Canadian institution”)

Quarter vs. semester miscalculation:

If you are at a quarter-system school:

• 3 quarters ≈ 2 semesters
• 2 quarters might be interpreted as 1.3–1.5 semesters and may not satisfy a “full year” requirement in the eyes of some schools

A student who covers two quarters of physics assumes, incorrectly, that this equals a full year. A few schools disagree. That single misalignment can limit their options or force an extra quarter.

Old coursework problems:

Some schools specify:

• “Prerequisite coursework must be completed within 5–10 years of application.”

If you took:

• General chemistry as a dual-enrollment high school student 9 years ago
• Intro biology freshman year and are now applying as a non-traditional senior, or after gap years

Those courses may be considered stale. You may technically have credit, but not functionally satisfy recency expectations.

Minimum grade in each prerequisite:

Another overlooked requirement: not just cumulative GPA, but minimum grades in each required course. A C– in Organic II might:

• Trigger an automatic rejection at a school that specifies C or above
• Force you to retake the course if you want to remain eligible

How to avoid this:

1. For each target school, specifically check:

   • “Time limit” or “recency” of coursework
   • Whether 2 quarters are accepted as 1 year (often they will tell you)
   • Any mention of “upper-division biology” required or recommended
   • Minimum acceptable grade in each course

2. If something is unclear, call or email admissions:

   • Ask: “I completed X and Y, would this fully satisfy your biology requirement?”
   • Save their response.

3. If your courses are older than 5–7 years, expect to refresh them through post-bacc or upper-level science coursework, especially if you were not a science major.

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5. Not Aligning Prerequisites with MCAT Preparation

There is a dangerous assumption: “If I complete the prerequisites, I will be prepared for the MCAT.”

Not always.

Two types of planning errors show up here:

1. Taking prerequisites too far before the MCAT and failing to reinforce them.
2. Taking critical content courses after the MCAT, leaving you underprepared.

Courses with heavy MCAT overlap:

• General biology I & II
• General and organic chemistry sequences
• Biochemistry
• Introductory psychology
• Introductory sociology
• Physics (especially foundational concepts, even though test emphasis has shifted)

Underpreparation scenario:

A student takes:

• Gen Chem I & II in freshman year
• Physics I & II sophomore year
• Organic I junior fall, Organic II and Biochem junior spring
• MCAT at the end of junior spring, but has not taken psychology or sociology

They have to self-teach half of the psych/soc content from review books while drowning in organic and biochem exam stress. Scores suffer.

Another student spreads biology across 3 years and then leaves a 2-year gap before the MCAT, without reinforcement. By test day, much of the detail is gone.

How to avoid this:

1. Backwards plan from your MCAT date:

   • If testing in April of junior year, try to have:
     • Bio I & II completed by end of sophomore year
     • Chem I & II and Organic I done by end of sophomore or early junior
     • Biochem, psych, and soc completed or at least in-progress before the MCAT

2. Avoid leaving entire MCAT sections dependent on self-study. One or two content areas can be self-taught; whole disciplines should not be.

3. If a course must be taken early (e.g., Gen Chem freshman year), use:

   • Light review every semester
   • Anki or spaced repetition
   • Occasional MCAT-style practice passages

You are not just taking classes to check boxes. You are building the knowledge base the MCAT will tax aggressively.

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6. Poor Communication and Documentation with Advisors and Schools

Even strong planners sabotage themselves by failing to document and verify.

Common communication errors:

• Assuming the premed advisor is always up to date on each school’s prerequisites
• Changing majors or transferring schools without re-mapping prerequisites
• Failing to keep syllabi, making it impossible to prove course content when a school questions it
• Not confirming case-by-case approvals in writing

Advisor overreliance example:

A student at a small liberal arts college is told by a single overworked premed advisor: “Our ‘Writing in the Humanities’ sequence counts as the English requirement for med schools. Students have been fine in the past.”

Three years later, one state school tightens its wording to “English department courses only.” The advisor has not updated their guidance. The student gets a late-cycle surprise that their two-course writing sequence may not count for that school.

How to avoid this:

1. Treat premed advising as a starting point, not a single source of truth.

2. Every time you rely on a “borderline” course:

   • Email 3–5 target schools with:
     • Course title and number
     • Syllabus attached
     • Specific question: “Can this satisfy your X requirement?”
   • Save all email responses in a dedicated folder.

3. After any transfer or major change:

   • Rebuild your prerequisite audit from scratch based on your new institution’s course catalog and your target schools’ websites.

4. Keep digital copies of syllabi:

   • The semester ends, your LMS access disappears, and suddenly you cannot prove that your “Topics in Biology” course included substantial molecular genetics content. This is preventable.

Paper trails protect you when policies seem inconsistent or when an admissions office staff member interprets something narrowly.

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7. Underestimating How Missing Prereqs Can Delay or Block Your Cycle

The worst outcome of these mistakes is not mild inconvenience. It is a full-cycle delay or a forced, narrow school list.

Consequences include:

• Having to delay application by an entire year while you complete 1–2 missing courses.
• Being suddenly ineligible for your home state school because of one misclassified course.
• Needing an expensive post-bacc year just to fix prerequisites that could have been planned as an undergrad.
• Losing early acceptance or special program eligibility.

Concrete delayed-cycle scenario:

You discover in March of your planned application year that:

• Your “online biology with lab” is not accepted by 8 of your 15 target schools.
• Your two-quarter physics sequence is considered insufficient by 3 more.

You scramble to register for summer physics or biology, but the courses:

• Fill quickly
• Overlap with your MCAT review timeline
• Produce rushed, weaker grades

Now you face a choice:

• Apply this year with a compromised school list and partial prerequisites, risking many automatic rejections.
• Or postpone one full cycle and apply after completion with better grades but lost time.

Both options are heavy costs for something that could have been avoided with earlier, more cautious planning.

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Your Action Checklist: Preventing Prerequisite Planning Errors

Here is what you can do this week to protect yourself:

1. Draft a preliminary school list (10–20 schools, including your state MD and at least 2–3 DO programs).
2. Build a prerequisite spreadsheet:
   • Include: Bio, Chem, Org, Physics, Biochem, English, Math/Stats, Psych/Soc, any upper-division bio, and special requirements.
3. Audit your completed and planned courses against that sheet:
   • Mark each requirement as: Completed / Planned / Missing / Unclear.
4. Flag “unclear” items:
   • AP credit use
   • Online labs
   • Interdisciplinary or writing-intensive substitutions
5. Email 3–5 schools about at least one ambiguous course this week. Get real answers and save them.
6. Sketch a semester-by-semester plan through graduation:
   • Place prerequisites in reasonable clusters
   • Avoid extreme science piles during your MCAT semester

Do not wait until the spring before you apply to discover these gaps. By then your options are limited, and you are stuck making the least-bad choice instead of a good one.

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FAQ

1. Can I still apply if some prerequisites are “in progress” when I submit my application?

Often yes, but with caveats. Many schools allow you to apply with certain courses in progress, as long as they are completed before matriculation. However, some insist that specific prerequisites (commonly core sciences) be completed before you apply or before interview. You must check each school’s wording carefully. If a core prerequisite will not even be started until after you submit, assume it will weaken or block your application at a subset of programs.

2. Do medical schools really care where I take my prerequisites (community college vs. university, online vs. in-person)?

Some do, some do not, and others have unofficial preferences that show up in their admitted class profiles. Many schools accept community college credits, but if most of your science prerequisites are from less rigorous or fully online environments, committees may question your preparation. When in doubt, prioritize in-person labs at a 4-year institution for your core sciences. If you must use community college or online courses, confirm acceptability with schools and balance them with strong upper-level science performance at a 4-year institution when possible.

3. I already graduated and discovered missing prerequisites. Should I do a full post-bacc program or just take individual courses?

If your GPA is strong and your main issue is missing or misaligned prerequisites, targeted coursework (a few individual classes at a local university or reputable online-with-in-person-lab option) may be sufficient. Formal post-bacc programs are more appropriate when you also need GPA repair or a structured science curriculum. Before committing to a full post-bacc (with its cost and time), list exactly which courses you are missing, estimate credits, and compare that against post-bacc requirements. Then email a few medical schools describing your situation to see whether targeted classes would meet their expectations.

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Open your transcript or degree audit today and put it next to two real medical school prerequisite pages. Do not trust your memory or generic lists. Line them up, course by course, and see if anything does not match. Catching the mismatch now is the difference between a clean application cycle and a delayed, expensive, avoidable detour.