Our blueprint estimate puts 5–10 of the 200 questions in biochemistry, about 3.8% of the paper, spread across both papers. It is our estimate, not a figure published by the RCOG. A moderate share of the paper, and reliably examined.
5–10
of 200
7
in our syllabus map
cell_function
2 other areas
Biochemistry is a smaller area, and the questions are narrower than the syllabus list suggests. They concentrate on steroid synthesis, metabolism in pregnancy, and the enzymes and markers you will meet again in clinical practice.
The 7 syllabus topics we map to Biochemistry for Part 1.
The placenta lacks some enzymes and depends on the fetal adrenal for precursors, which is why a placental enzyme deficiency can give low oestriol in a normal fetus. Know which cell type carries which enzyme.
Glucose crosses the placenta by facilitated diffusion; insulin does not. That asymmetry explains fetal hyperinsulinaemia in a mother with poorly controlled diabetes, and it recurs across several question types.
Alkaline phosphatase rises in pregnancy from placental production, while a raised transaminase does not have a placental explanation. Reading liver enzymes correctly is a common point of separation between candidates.
Folate, iron and vitamin D come up as nutritional biochemistry. Concentrate on what each does, the deficiency state it causes, and the pregnancy-specific reason for supplementing.
Because this area is small, give it short, frequent sessions rather than a block. Pair each enzyme with the tissue that expresses it and the clinical state that follows when it is absent. Revise it alongside endocrinology so the two-cell model is learned once and reused, and keep a short list of the laboratory markers that behave differently in pregnancy.
Part 1 is 200 single best answer questions across two papers with no negative marking, so an informed guess always beats a blank. Biochemistry is a medium-yield area in our blueprint, so it is worth learning efficiently rather than exhaustively. Most of its content is shared with endocrinology, and revising the two together saves time.
Every question is original and written from published RCOG and NICE guidance, and every explanation cites the guideline it came from. Free: 5 days full access, then 50 questions. No card.
Published RCOG and NICE guidance summarised for revision, with the source cited on every page.
MRCOG AI is an independent educational tool. It is not affiliated with, endorsed by, or connected to the Royal College of Obstetricians and Gynaecologists (RCOG).