Edexcel IAL A2 Biology specification — Units 4, 5 and 6 checklist
The A2 half of the Pearson Edexcel IAL Biology specification (Issue 2), point by point: Topics 5 to 8 across Units 4 and 5, and the practical skills examined in Unit 6. Tick each point as you master it; progress is saved on your device. Alongside each topic is what the last six years of papers actually asked, so you know which points to learn first.
Jump to a unit
Watch first
How the A2 units decide the A* — worth three minutes before you start ticking.
Study these 10 topics for your IAL Unit 4 Biology Exam
Topic 5–6 priorities
10 Unit 5 IAL Biology Topics That Could Save Hours of Revision
Topic 7–8 priorities
This practical appears in nearly all Unit 3 and Unit 6 exams
Core practical focus
How the A2 specification is organised
Pearson splits A2 into two theory units and one practical unit. Unit 4 (WBI14) holds Topic 5, Energy Flow, Ecosystems and the Environment, and Topic 6, Microbiology, Immunity and Forensics. Unit 5 (WBI15) holds Topic 7, Respiration, Muscles and the Internal Environment, and Topic 8, Coordination, Response and Gene Technology, plus the pre-released scientific article. Unit 6 (WBI16) has no topics of its own: it assesses planning, implementation and analysis using the core practicals from Units 1, 2, 4 and 5.
Every specification point is written with a command verb — know, understand, be able to — and the mark scheme is written to that verb. A point that says "understand" will be examined with "explain"; a point that says "be able to" will be examined with "calculate" or "describe how". Reading the verb tells you the question before you see it.
Which specification points are examined most
Across 51 papers from 2020 to 2026, the specification is not examined evenly. In Topic 5, climate-change evidence and models, sampling and succession, and the light-dependent reactions dominate; the Calvin cycle and forensics are examined far less. In Topic 6, microbial growth and immunity carry most of the marks. In Topic 7, the control of heart and breathing rate, the stages of respiration and the kidney lead; in Topic 8, the nervous system alone is a quarter of the Unit 5 paper, while the eye, the brain and plant coordination are examined rarely. The nine A2 core practicals all appear in Unit 6, with ecology of a habitat first.
That does not mean skipping the low-frequency points — one "Suggest" question on a rarely examined point is still five marks. It means learning in order: the high-frequency points until they are automatic, then the rest.
Using this checklist
Work one topic at a time in specification order for first teaching, or in the marks order above for revision. Tick a point only when you can write its mark-scheme phrase from memory and have answered a past question on it. The checklist saves on this device and resets with one button. For the full official wording, assessment objectives and sample papers, use the Pearson specification linked below.
FAQ
Which specification version is this?
Pearson Edexcel International Advanced Level in Biology, Issue 2 (2018 qualification, first A2 assessment 2020). All current papers are set on it.
Do Units 4 and 5 examine Unit 1 and 2 content?
Yes. Both A2 theory papers are synoptic; questions can draw on any AS specification point, most often from Topics 1 and 2.
Which core practicals are in Unit 6?
CP 10–18 from Units 4 and 5 directly, and any of CP 1–9 from Units 1 and 2. Ecology of a habitat (CP 11) is examined most often.
Is there an A2 practical exam?
No. Practical skills are assessed on the written Unit 6 paper.
About
About this page. This is a condensed, interactive version of the A2 half of the Pearson Edexcel International Advanced Level in Biology specification (Issue 2) — Topics 5 to 8 examined in Units 4 and 5 (WBI14, WBI15) and the practical skills examined in Unit 6 (WBI16). The notes on which points are examined most come from Chem Bio's classification of every question part in 51 A2 papers from 2020 to 2026. It is a study companion, not a replacement for the official document. Written by Hosni Showike, Head of Science, 21 years teaching Edexcel IAL Biology.
Continue with
Last updated 3 September 2026
