This is a fidelity audit for candidates deciding whether to rely on PassPaeds for MRCPCH Theory and Science (TAS). It is written for the trainee weighing coverage, question style and limitations before committing, rather than looking for another "best bank" ranking. The principal limitation to state at the outset: PassPaeds markets its TAS questions as part of a combined "FOP & TAS" pool, so the headline total does not tell you how much genuinely science-and-mechanisms material it holds — and TAS is the paper where mechanisms, not recall, decide the result.
What PassPaeds offers for TAS right now
| Item | Vendor-reported position, checked 20 July 2026 |
|---|---|
| TAS provision | Marketed within a combined "FOP & TAS" bank, "over 2,600" questions for the first written stage |
| Price | 4 months £20; 6 months £30 (vendor-reported) |
| Format | SBAs to the current RCPCH syllabus, each with answer and revision notes |
| Analytics | Daily peer-comparison histogram; a spaced-repetition "knowledge tutor" |
| Adaptive AI | None published; the "knowledge tutor" is spaced repetition, not an adaptive-difficulty engine |
| TAS-specific count | Not separately published — the site does not state how many of the 2,600 are TAS-science items |
These are vendor-reported figures, correct at the last check on 20 July 2026. The audit finding to carry forward is in the last row: because PassPaeds bundles FOP and TAS, you cannot tell from the product page how much of the pool tests TAS-level science versus FOP-level clinical recall. Verify this on passpaeds.com, and do not treat 2,600 as 2,600 TAS questions.
The TAS exam: what you are actually preparing for
TAS is 100 single best answer questions in 2 hours, one paper, one mark each, no negative marking, computer-based. It is the science-and-mechanisms paper: basic scientific, physiological and pharmacological principles plus evidence-based practice. Expect mechanism of action of drugs such as antibiotics and anti-epileptics, genetics, metabolic medicine, physiology, statistics and critical appraisal, and less ward-familiar topics such as ophthalmology and tropical medicine. Unlike Foundation of Practice, clinical experience will not carry you — TAS rewards book study. The three theory exams may be sat in any order and all precede the separate MRCPCH Clinical OSCE. The RCPCH TAS specimen is the calibration anchor, noting it sits on the previous system with extended matching questions no longer used.
Read the count by domain, not by headline
The single most useful audit action is to ignore the headline number and rebuild it by domain. Sample the bank and tally how many items you meet in each low-volume TAS domain — genetics, metabolic medicine, statistics, ophthalmology, pharmacology mechanisms — rather than trusting "over 2,600". A combined FOP/TAS pool can be large and still thin on exactly the mechanistic science TAS tests, because the bulk of a combined bank naturally sits in the clinically applicable FOP material. If a domain returns only a handful of items on sampling, that is a coverage gap the headline concealed.
Sample the question style: recall versus application
Audit a stratified sample against these axes:
- Recall versus application: does the item ask you to recognise a fact, or to reason from a mechanism to a consequence? TAS leans on the latter; a bank heavy on single-fact recall under-prepares you.
- Stem length and data: TAS stems can be short and conceptual or data-rich; check both are represented.
- Option plausibility: are the distractors genuinely tempting, or is the key obvious? Weak distractors inflate your accuracy and teach nothing.
- Image and data interpretation: are graphs, pedigrees and results actually present, or described in prose?
- Management sequencing: where relevant, does the item test the next correct step rather than a static fact?
Where a sample skews to easy recall with weak distractors, the bank builds recognition, not the mechanistic reasoning TAS rewards.
Jurisdiction and recency
Check a stratified sample against current official or primary guidance and record the date you did so. For UK paediatric practice, that means NICE, CKS, SIGN, RCPCH and NHS content, and the SmPC via the eMC for medicines. Pharmacology and evidence-based-practice items date faster than physiology; flag any item whose answer no longer matches current guidance, and note that a bank's revision notes are secondary to the primary source.
The format gap: what a standard bank cannot do
State it plainly. A standard SBA bank is well suited to breadth, spaced recall and pacing, and it can rehearse a great deal of TAS content. What it cannot fully do is teach mechanistic reasoning — deriving why a pathway, drug or physiological principle behaves as it does — or the depth of critical appraisal TAS expects. Those require primary reading and worked derivation, not more multiple-choice recognition. Genetics, physiology and metabolic reasoning in particular reward source study; a bank confirms whether it landed, it does not build it. The practical consequence is that your TAS revision has to be layered: read the mechanism from a primary source, then use the bank to check retention and pacing, rather than expecting the bank to teach the derivation in the first place. A candidate who inverts that order — grinding questions in the hope the science will accrete — tends to plateau, because recognition of an explanation is not the same as being able to reason from the principle to a novel stem.
Duplication and contamination
The larger risk in a big combined pool is that repeated concepts and near-duplicate stems turn revision into recognition. When the same handful of high-yield facts recur across dozens of items, a rising accuracy reflects familiarity with the bank, not readiness for the exam. Sample for near-duplicates, and once you notice you are answering from memory of the stem rather than the science, that domain is exhausted — move to unseen material to measure whether the knowledge transfers.
A worked audit
Suppose you sample 120 PassPaeds items spread across the TAS domains and tally them. Physiology and pharmacology return plenty of items, but genetics yields nine, metabolic medicine six, and statistics and critical appraisal eleven — and of those, most are single-fact recall with one obviously correct option rather than mechanistic reasoning. That is the audit result that matters: the headline pool is large, yet three science domains central to TAS are both thin and shallow. The correct response is not to do the 2,600 questions faster; it is to read primary sources for those three domains, then measure transfer on unseen items. A completion percentage would have concealed all of this behind a single reassuring number, which is exactly the failure mode the audit is built to prevent.
Best-fit matrix
| Use case | Fit for PassPaeds (TAS) |
|---|---|
| Foundation building | Reasonable for breadth, weaker for mechanism depth |
| First-pass bank | Reasonable, given low cost and syllabus mapping |
| Second/measurement bank | Poor — combined pool risks overlap; use an unseen bank instead |
| Retake preparation | Partial — audit domain coverage first |
| Final unseen simulation | Poor — you will have seen the items; use a reserved unseen set |
A seven-day plan for a busy trainee
PassPaeds does one job — first-pass breadth on the combined pool — and iatroX supplies unseen transfer measurement. No proprietary-algorithm claims are made for either.
- Day 1: Sample-and-tally audit — map PassPaeds items by TAS domain; flag thin science areas.
- Day 2: Two PassPaeds blocks on your weakest science domains; error-code every miss.
- Day 3: Source reading on the mechanisms you missed (physiology, pharmacology), then one fresh iatroX transfer item each.
- Day 4: Timed random 100-item block; review flags only.
- Day 5: Currency check on statistics and pharmacology items against primary sources.
- Day 6: RCPCH TAS specimen, timed, for content calibration.
- Day 7: Rest or light spaced review.
Decision checklist: continue, supplement, switch or stop
- Continue PassPaeds while it is still surfacing new TAS-science material and your misses are foundational.
- Supplement with primary reading for mechanisms and an unseen bank for measurement — the combined pool cannot serve as its own measurement layer.
- Switch primary banks if your domain audit shows the science areas are genuinely thin, not just unpractised.
- Stop new questions when domain coverage, unseen timed accuracy, pacing, retention and specimen calibration all hold.
Three mistakes this audit is designed to stop
First, reading "over 2,600" as 2,600 TAS questions when the pool is a combined FOP/TAS bank. Second, revising TAS from clinical experience as if it were Foundation of Practice, when it rewards book study. Third, letting near-duplicate stems in a large pool inflate your accuracy in the final fortnight instead of measuring on unseen items.
Bottom line
For TAS, PassPaeds is a low-cost, syllabus-mapped option that is a reasonable first-pass resource — but the combined FOP/TAS packaging means you must audit its science coverage by domain rather than trusting the headline, and the mechanistic reasoning at the heart of TAS needs primary reading a standard bank cannot replace. Use PassPaeds for breadth, read sources for mechanism, and reserve an independent unseen bank such as iatroX to confirm transfer — then let coverage and unseen performance, not a completion percentage, decide when to stop.
FAQ
Is PassPaeds enough for MRCPCH Theory and Science on its own? For TAS specifically it is less likely to be sufficient alone than it is for Foundation of Practice, because TAS tests scientific mechanisms that reward primary reading and because PassPaeds bundles TAS within a combined pool whose science depth you must verify. Treat it as a breadth resource, add source study for mechanisms, and measure readiness on unseen timed blocks and the RCPCH specimen.
Which MRCPCH Theory and Science component does PassPaeds not reproduce well? The mechanistic and derivational reasoning — physiology, pharmacology mechanisms, genetics and the depth of critical appraisal — is what a standard SBA bank reproduces least well, and it is exactly what TAS prioritises. PassPaeds can confirm whether you know a fact; it is weaker at building the underlying reasoning, and it does not touch the separate MRCPCH Clinical OSCE.
How many PassPaeds questions should I complete per day for MRCPCH Theory and Science? Let review capacity set the number, which for most working trainees is about 40–60 items a day, because a TAS miss usually needs a short source read to understand the mechanism rather than just noting the answer. Grinding high volume without that mechanistic review trains recognition and leaves the science unlearned.
When should I stop using PassPaeds and move to mixed mocks? Stop first-pass practice and move to timed mixed mocks once your domain audit shows the science areas are covered, your foundational recall is stable and near-duplicate stems are starting to make the questions feel familiar. Familiarity with the pool is itself the signal to measure yourself on unseen material instead.
How should I combine PassPaeds with iatroX without duplicating practice? Apply the two-Q-bank rule and separate the jobs: PassPaeds for first-pass breadth, iatroX as the reserved unseen-measurement layer for fresh timed transfer questions. Because a combined pool already risks internal overlap, it is especially important not to add external duplication — keep the measurement bank unseen so it can actually measure.
Editorial notes and references
Written by Dr Kolawole Tytler, NHS GP and founder of iatroX. Last checked 20 July 2026. PassPaeds figures — the combined "FOP & TAS" pool of over 2,600 questions, price and the spaced-repetition knowledge tutor — are vendor-reported from passpaeds.com and may change; the TAS-specific count is not separately published, so verify coverage by domain before relying on it. Disclosure: iatroX operates a competing UK question bank; here its role is confined to the unseen-measurement and transfer-practice jobs PassPaeds does not claim, not to replacing it for TAS breadth or the MRCPCH Clinical OSCE. Corrections are welcome via the feedback route on iatrox.com.
References: RCPCH, Theory exams — structure and syllabi and theory exam sample papers; PassPaeds; iatroX, Your Q-Bank Percentage Is Not Your Exam Score; iatroX, question-bank completion is not coverage; iatroX, the two-Q-bank rule; iatroX comparison hub.
Run a fresh, timed MRCPCH Theory and Science block in iatroX →