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Wales Β· WJEC2026

WJEC A-Level Biology: complete guide to the four units and the exams

A complete guide to WJEC A-Level Biology (Wales). Covers the four examined units (Basic Biochemistry and Cell Organisation; Biodiversity and Physiology of Body Systems; Energy, Homeostasis and the Environment; Variation, Inheritance and Applications), the practical assessment, how the AS and A2 papers are structured and marked, and how to study each unit for top grades.

Browse guides β†’Syllabus dot points (22)

WJEC A-Level Biology (Wales) is a two-year course with an AS year and an A2 year, assessed by written unit papers and a practical examination. This page is the index: below is a map of the four content units, the synoptic paper, the exam structure, and how to study each one.

The four WJEC Biology units

The specification organises the content into four units. Units 1 and 2 are the AS content and first year; Units 3 and 4 are the A2 content, drawn together by the synoptic Unit 5.

Unit 1 Basic Biochemistry and Cell Organisation
Chemical elements and biological molecules (water, carbohydrates, lipids and proteins), cell structure and organisation, cell membranes and transport, biological reactions and enzymes, nucleic acids and replication, and cell division.
Unit 2 Biodiversity and Physiology of Body Systems
Classification and biodiversity, adaptations for gas exchange, adaptations for transport, adaptations for nutrition, and the effect of infectious disease.
Unit 3 Energy, Homeostasis and the Environment
The importance of ATP and photosynthesis, respiration, microbiology, population size and ecosystems, human impact on the environment, homeostasis and the kidney, and the nervous system.
Unit 4 Variation, Inheritance and Applications
Sexual reproduction in humans and plants, inheritance and variation, applications of reproduction and genetics, and the musculoskeletal system.

The synoptic paper

The A2 year is drawn together by a synoptic written paper that includes a comprehension passage, a data-analysis task and questions that combine content from across the units, so cross-unit fluency matters.

Exam structure

WJEC A-Level Biology is assessed by written unit papers and a practical examination. A calculator is provided in every paper.

  • Unit 1 Basic Biochemistry and Cell Organisation - AS written paper of structured questions and an extended response.
  • Unit 2 Biodiversity and Physiology of Body Systems - AS written paper of structured questions and an extended response.
  • Unit 3 Energy, Homeostasis and the Environment - A2 written paper of structured questions and extended responses.
  • Unit 4 Variation, Inheritance and Applications - A2 written paper of structured questions and extended responses.
  • Unit 5 - synoptic A2 paper with a comprehension, data analysis and content from across the course.
  • Practical examination - assesses experimental and analytical skills separately from the written papers.

A significant share of marks assess maths skills, and the specified practicals recur across the written papers and the practical examination.

How to study WJEC Biology

Biology rewards precise wording, clear diagrams and confident data handling.

  1. Work from the specification statements. Each statement is a checklist; questions are written from them.
  2. Learn definitions and processes exactly. Mark schemes reward precise terms, such as denaturation, water potential, and semi-conservative replication.
  3. Drill the calculations. Magnification, genetic ratios, the index of diversity and rates from graphs must be automatic.
  4. Master the specified practicals. The food tests, enzyme experiments, microscopy and dissections recur across the papers and the practical examination.
  5. Practise the synoptic style. Rehearse the comprehension and data-analysis tasks and apply concepts to unfamiliar contexts from early in the A2 year.

The four units, topic by topic

Each unit has a topic-level overview with worked exam questions and cross-links, plus dot-point answer pages for each specification statement.

For the official specification

WJEC publishes the full specification, past papers and mark schemes at wjec.co.uk. Always revise from the current specification and WJEC's own past papers, because question style is board-specific.

Biology guides

In-depth written guides with paired practice quizzes.

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Biology practice quizzes

Multiple-choice drills with worked answer explanations. Your scores stay on this device.

The WJEC-A-LEVEL system, explained

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Common questions about Biology

How is WJEC A-Level Biology structured?
WJEC A-Level Biology is a two-year course with an AS year and an A2 year. The AS comprises Unit 1 (Basic Biochemistry and Cell Organisation) and Unit 2 (Biodiversity and Physiology of Body Systems), each examined by a written paper. The A2 adds Unit 3 (Energy, Homeostasis and the Environment) and Unit 4 (Variation, Inheritance and Applications), plus a synoptic Unit 5 written paper. Practical skills are assessed separately. AS results count towards the full A-level, and the qualification follows the 2015 WJEC specification used in Wales.
What are the WJEC A-Level Biology exam papers?
At AS, Unit 1 (Basic Biochemistry and Cell Organisation) and Unit 2 (Biodiversity and Physiology of Body Systems) are each a written paper of structured questions and at least one extended response. At A2, Unit 3 (Energy, Homeostasis and the Environment) and Unit 4 (Variation, Inheritance and Applications) are each a written paper, and Unit 5 is a synoptic paper that mixes a comprehension, data analysis and content from across the course. Practical skills are assessed through a separate practical examination.
How much maths is in WJEC A-Level Biology?
A significant share of the marks assess mathematical skills. Expect magnification and actual-size calculations with unit conversions, ratios and probabilities in genetic crosses, the index of diversity, mitotic index, rates from graphs, and interpreting data such as oxygen dissociation curves and growth curves. A calculator is allowed in every paper.
How is practical work assessed in WJEC A-Level Biology?
Practical skills are assessed through a practical examination rather than continuous coursework, and the specified experiments also appear in the written papers. WJEC lists specified practicals such as the biochemical food tests, investigating enzyme activity, using a microscope and calculating magnification, investigating membrane permeability, and the dissection of organs. You should be able to plan, carry out, analyse and evaluate experiments.
How should I structure my WJEC A-Level Biology revision?
Work unit by unit against the specification statements, because questions are written directly from them. Biology rewards precise wording, so learn definitions and processes exactly, drill the calculations (magnification, genetic ratios, diversity), and practise the specified-practical methods and data analysis for the practical examination and Unit 5. Rehearse the comprehension and synoptic style and apply concepts to unfamiliar contexts from early in the A2 year.
How does WJEC A-Level Biology compare to other exam boards?
All A-Level Biology specifications cover the same core regulated content, so cells, biochemistry, genetics and physiology are broadly the same everywhere. WJEC's distinctive features are its four-unit content structure, the synoptic Unit 5 with its comprehension and data-analysis sections, and its own list of specified practicals. WJEC and Eduqas share much of the same content, but always revise from the current WJEC specification and WJEC past papers, because question style is board-specific.
What's the difference between mitosis and meiosis?
Mitosis produces two identical diploid cells (for growth and repair). Meiosis produces four genetically distinct haploid cells (for sexual reproduction).
How does protein synthesis work?
Transcription (DNA β†’ mRNA in the nucleus) then translation (mRNA β†’ polypeptide at the ribosome). tRNA brings amino acids that the ribosome links into the protein sequence the mRNA codes for.
What's homeostasis?
The maintenance of a stable internal environment (temperature, blood glucose, pH) despite external change β€” usually via negative feedback loops involving receptors, control centres, and effectors.
How does evolution by natural selection work?
Variation exists in a population β†’ some variants survive and reproduce better in a given environment β†’ those traits become more common over generations. Requires heritable variation, differential reproductive success, and time.
What's the difference between an antibody and an antigen?
Antigen: a molecule (often on a pathogen) that triggers an immune response. Antibody: a Y-shaped protein the immune system makes to bind specifically to that antigen.