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Northern Ireland · CCEA2026

CCEA A-Level Biology: complete guide to the modules, the AS and A2 exams and how to study each topic

A complete guide to CCEA A-Level Biology (specification 2016). Covers the molecules and enzymes, cells, physiology and genetics modules, the practical and mathematical skills, how the AS and A2 exams are structured and marked, and how to study each module for top grades.

Browse guides →Syllabus dot points (23)

CCEA A-Level Biology (specification first taught 2016) is a two-year course split into AS and A2, set and marked by CCEA in Northern Ireland. This page is the index: below is a map of the four content modules, the practical and mathematical skills, the assessment structure, and how to study each module.

The CCEA Biology modules

The specification groups the subject content into four broad areas, studied across the AS and A2 units.

Molecules and Enzymes
The chemical foundation. It covers biological molecules (carbohydrates, lipids and proteins), water and inorganic ions, enzymes and the induced-fit model, and nucleic acids including DNA replication and ATP. The unifying idea is that molecular structure determines biological function.
Cells, Viruses and Reproduction
The cell-biology module. It covers cell structure and membranes, transport across membranes, viruses and their replication, cell division and reproduction by mitosis and meiosis, and gas exchange and transport. The unifying ideas are organisation and exchange across surfaces.
Physiology, Coordination and Control
The systems module. It covers homeostasis and the kidney, the nervous system, hormonal control, photosynthesis and respiration, and plant coordination. The unifying idea is negative feedback and the coordinated control of internal processes.
Genetics, Evolution and Ecosystems
The synoptic module. It covers genetics and inheritance, gene technology, populations and evolution, ecosystems and conservation, and immunity. The unifying ideas are heredity, change over time, and the flow of energy and recycling of matter.

Practical and mathematical skills

Practical skills are compulsory and assessed in dedicated units (AS 3 and A2 3), which include a practical examination and an investigative task rather than a separately graded report. Mathematical skills are embedded throughout: magnification and scale calculations, the chi-squared test, Hardy-Weinberg allele frequencies, rates from graphs, and data and uncertainty handling. These skills are examined across the written papers as well as in the practical units.

Assessment structure

CCEA A-Level Biology is split between AS (40 percent) and A2 (60 percent), with both written papers and assessed practical units.

  • AS 1 Molecules and Enzymes - a written paper on the biological molecules, water, enzymes and nucleic acids content.
  • AS 2 Cells, Viruses and Reproduction of Cells - a written paper on cells, membranes, viruses, cell division and gas exchange.
  • AS 3 Practical Skills in Assessment of Biology - assessment of practical and investigative skills.
  • A2 1 Physiology, Coordination and Control, and Ecosystems - a written paper extending into homeostasis, control systems and ecology.
  • A2 2 Biochemistry, Genetics and Evolutionary Trends - a written paper on metabolism, inheritance, gene technology and evolution.
  • A2 3 Practical Skills in Assessment of Biology - a practical examination and investigative task.

How to study CCEA Biology

Biology rewards precise terms, structure-to-function links, and ordered process explanations.

  1. Work from the specification statements. Each numbered point is a checklist; questions are written from them.
  2. Learn definitions and named structures precisely. Bonds, enzymes, organelles and ions are tested by name.
  3. Link structure to function. In every topic, explain how a structure suits its role, from cellulose fibres to the nephron.
  4. Rehearse processes as sequences. Order the steps of the action potential, the nephron, respiration and the immune response.
  5. Drill the maths and practicals. Magnification, chi-squared and Hardy-Weinberg calculations recur, and the practical units demand confident technique and data analysis.

The modules, dot point by dot point

Each module has a specification-level overview with worked questions and cross-links, plus dot-point pages and a quiz. Browse the full set at /ccea-a-level/biology/syllabus.

For the official specification

CCEA publishes the full specification, past papers and mark schemes at ccea.org.uk. Always revise from the current CCEA specification and CCEA's own past papers, because question style and practical expectations are 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 CCEA-A-LEVEL system, explained

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Common questions about Biology

How is CCEA A-Level Biology structured?
CCEA A-Level Biology is a two-year course split into AS and A2. AS has two examined units, AS 1 Molecules and Enzymes and AS 2 Cells, Viruses and Reproduction of Cells, plus AS 3 which assesses practical skills, and the AS counts for 40 percent of the full A-Level. A2 has A2 1 Physiology, Coordination and Control, and Ecosystems and A2 2 Biochemistry, Genetics and Evolutionary Trends, plus A2 3 which assesses practical skills, and the A2 counts for 60 percent. Practical and mathematical skills are embedded throughout.
What are the CCEA A-Level Biology exam papers?
At AS, AS 1 Molecules and Enzymes and AS 2 Cells, Viruses and Reproduction of Cells are each a written paper, and AS 3 assesses practical skills. At A2, A2 1 Physiology, Coordination and Control, and Ecosystems and A2 2 Biochemistry, Genetics and Evolutionary Trends are written papers, and A2 3 assesses practical skills, including a practical examination and an investigative task. Papers use structured short-answer questions, data and calculation questions, and extended writing.
What topics are in CCEA A-Level Biology?
The content is grouped into four broad areas. Molecules and Enzymes covers biological molecules, water and inorganic ions, enzymes and nucleic acids. Cells, Viruses and Reproduction covers cell structure and membranes, transport, viruses, cell division and gas exchange. Physiology, Coordination and Control covers homeostasis and the kidney, the nervous system, hormonal control, photosynthesis and respiration, and plant coordination. Genetics, Evolution and Ecosystems covers inheritance, gene technology, populations and evolution, ecosystems and immunity.
How much practical and maths work is in CCEA A-Level Biology?
Practical skills are compulsory and assessed in dedicated units (AS 3 and A2 3), which include practical examinations and investigative tasks rather than a separately graded coursework report. Mathematical skills run throughout: students use magnification and scale calculations, statistics such as the chi-squared test, Hardy-Weinberg allele frequencies, rates from graphs, and the handling of data and uncertainty. A calculator is allowed in the written papers.
How should I revise CCEA A-Level Biology?
Work module by module against the specification statements, because questions are written from them. Learn key definitions and named bonds, enzymes and structures precisely, link structure to function in every topic, and rehearse each process (such as the action potential, the nephron and respiration) as an ordered sequence. Drill the genetic and statistical calculations, practise data-response and extended-answer questions under timed conditions, and prepare thoroughly for the practical units.
How does CCEA A-Level Biology compare to other exam boards?
All A-Level Biology specifications cover the same regulated core, so biological molecules, cells, genetics, homeostasis and ecology appear everywhere. CCEA's distinctive features are its AS and A2 unit structure, its dedicated practical-skills units (AS 3 and A2 3) with a practical examination and investigative task, and its particular grouping of content into the molecules, cells, physiology and genetics units. Always revise from the current CCEA specification and CCEA past papers, because question style and practical expectations are 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 → mRNA in the nucleus) then translation (mRNA → 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 — usually via negative feedback loops involving receptors, control centres, and effectors.
How does evolution by natural selection work?
Variation exists in a population → some variants survive and reproduce better in a given environment → 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.