If you're sitting OCR Twenty First Century Biology B (spec code J257), there are 8 compulsory Practical Activity Groups you need to know. OCR calls them "PAGs" rather than required practicals: each PAG is a group of techniques, and your school picks one specific activity (or devises its own) that covers the apparatus and skills listed.
This guide walks through all 8 OCR B Biology PAGs in the specification's own order, explains how they're examined across the Breadth and Depth papers, and sets out the three important ways OCR B differs from OCR Gateway Biology A (J247). Different boards use different vocabulary for the same idea: OCR says "PAGs", AQA says "required practicals", Edexcel says "core practicals". This article is OCR Twenty First Century (OCR B) only. If you're on Gateway A, use our Gateway Biology practical guide instead.
This article was last checked against the OCR Twenty First Century Biology B (J257) specification on **14 October 2026**. OCR revises its specification wording from time to time, so cross-check the official spec PDF before relying on specific detail.
OCR has TWO Biology specs: Gateway A (J247) and Twenty First Century B (J257). Different structures, different content framing, different paper models. Gateway splits content by paper. Twenty First Century uses Breadth and Depth: both papers cover all chapters, differentiated by question style. Check your spec code before revising.
All 8 OCR B Biology PAGs
The OCR specification states that learners must complete at least eight practical activities, which OCR has split into eight Practical Activity Groups (PAGs) based on Department for Education GCSE subject content requirements. OCR B labels its PAGs PAG1 to PAG8. Gateway separate Biology (J247) refers to the same groups as PAG B1 to PAG B8, so letter-prefixed codes are not unique to Combined Science. At Higher tier the papers are J257/03 (Breadth) and J257/04 (Depth), each 1 hour 45 minutes, 90 marks, 50% of the qualification.
| PAG | Title | What it covers |
|---|---|---|
| 1 | Microscopy | Observations of biological specimens; labelled scientific drawings; measurement of length, area, mass, time, temperature, volume and pH |
| 2 | Testing for biological molecules | Qualitative reagents for sugars, starch, protein and lipids; continuous sampling in enzyme investigations |
| 3 | Sampling techniques | Distribution and abundance via field-work; quadrats and belt transects; biotic and abiotic factors |
| 4 | Rates of enzyme-controlled reactions | Bunsen burners or water baths; rate measurement; investigating pH or temperature range |
| 5 | Photosynthesis | Rate of photosynthesis measurement using an aquatic plant such as <em>Cabomba</em>; counting bubbles or measuring gas volume |
| 6 | Physiology, responses, respiration | Effect of exercise on pulse rate, ventilation rate and recovery time |
| 7 | Microbiological techniques | Antimicrobial agents on bacterial lawns; aseptic technique; measuring zones of inhibition |
| 8 | Transport in and out of cells | Osmosis using potato chips in different water potentials; percentage change in mass |
Because each PAG is a group of techniques rather than a prescribed experiment, two schools can teach PAG 4 using different enzymes (amylase and starch, or catalase and hydrogen peroxide) and both are valid. OCR publishes example activities but centres can substitute. When exam questions reference a PAG, they tend to describe the apparatus and ask you to apply the technique, rather than naming a specific experiment.
How practical skills are assessed
There's no separate practical exam for OCR B Biology. Practical skills are examined through written questions on both the Breadth and Depth papers, and your school signs a Practical Science Statement confirming you've completed the PAGs. The OCR specification states: "No less than 15% of the questions will assess practical skills." AO1 (demonstrate knowledge and understanding) and AO2 (apply knowledge and understanding) each account for 40% of the overall grade; AO3 (analyse information and ideas; interpret and evaluate; develop and improve experimental procedures) accounts for 20%.
OCR B also runs an entire chapter called B7 "Ideas about Science" on the separate Biology spec (J257), woven through every paper. B7 isn't a PAG, but it covers scientific method, data interpretation and ethics, and it uses real-world contexts to probe whether you can reason about scientific evidence. Many of the Depth-paper extended-response questions sit at the intersection of a PAG and B7.
The practical-skills chapter in OCR B separate Biology is Chapter B8. It brings together apparatus and techniques, measurement precision, and analysis of risk.
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Gateway vs 21st Century
OCR Twenty First Century Biology B differs from OCR Gateway Biology A on three axes.
PAG labelling. OCR B separate Biology (J257) has 8 PAGs labelled PAG1 to PAG8. OCR Gateway separate Biology A (J247) also has 8 PAGs, labelled PAG B1 to PAG B8 in the Gateway spec, with closely overlapping titles (microscopy, biological molecule tests, sampling, enzyme rates, photosynthesis, physiology/respiration, microbiological techniques, transport in and out of cells on both).
Paper structure. Gateway Biology splits content between papers. OCR B uses Breadth and Depth: both papers cover all chapters, differentiated only by question style. Breadth is multi-topic shorter questions; Depth is deeper application and extended-response synoptic reasoning. Don't go into the exam expecting "Paper 1 covers chapters X to Y" on OCR B, both papers cover everything.
B7 Ideas about Science. OCR B treats scientific method, data interpretation and ethics as an examinable chapter in its own right (Chapter B7 on separate J257), framed around real-world contexts. Gateway treats "Working Scientifically" differently and doesn't have a direct equivalent of B7 as a standalone examined chapter. Many OCR B questions use real contexts (screening programmes, antibiotic resistance, climate evidence) that would feel out of place on a Gateway paper.
OCR B separate PAGs are labelled PAG1 to PAG8. Gateway J247 uses PAG B1 to PAG B8. A list of only five (B1 Microscopy, B2 Sampling...) is a Combined Science list, not a separate Biology list.
Study tips for the 8 PAGs
Reading through the method isn't enough. PAGs test whether you can think like a scientist, not whether you can recite a recipe.
For each PAG, pick the activity your class ran and write the method out from memory. Then check it against your notes or a Cognito video. The steps you forgot are the ones that would have cost you marks. Pay attention to the small details OCR likes to probe: incubating microbiology plates at 25 degrees Celsius rather than 37 (to reduce the risk of pathogenic growth), taping agar lids rather than sealing them, blotting potato cylinders before weighing, measuring the diameter of the clear zone across the disc (and using pi r squared for its area).
Prepare answers for the four question types that keep coming up for every PAG: method, variables, explanation of results, evaluation. The vocabulary matters: a specific improvement with a specific reason, not "repeat it".
For the Depth paper, practise linking a PAG to B7 Ideas about Science reasoning. A question on PAG 7 (antibiotic plates) can swerve into evaluating whether a particular study was ethical, or how confident you can be in a conclusion given a small sample. The Depth paper rewards you for naming the uncertainty (sample size, confounders, variability) rather than just reporting the result.
Work through past paper questions by PAG. OCR recycles both wording and graph shapes year on year, and the mark schemes are the clearest guide to the exact phrases they want. Our guide to getting a grade 9 in GCSE Biology walks through exam technique, time management and revision strategies applicable across exam boards.
The Breadth paper rewards speed and precision across many topics; the Depth paper rewards extended reasoning. Match your practice to the paper: Breadth drills with past-paper short-answer sections, Depth drills with 6-mark and extended-response questions linking a PAG to B7.
How Cognito helps
Our OCR Twenty First Century Biology course covers all 8 PAGs through short video lessons, worked examples and exam-style questions. Each PAG has its own lesson walking through the technique, apparatus, variables and exam language. Jump into the OCR B Biology course and track your progress through the whole spec. For the wider shape of the qualification, our complete guide to OCR Twenty First Century GCSE Biology covers Breadth and Depth paper structure, chapter list and timing in one place.
