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Edexcel A-Level Biology B - Salters-Nuffield (9BN0): complete guide to the topics and the exams

A complete guide to Pearson Edexcel A-Level Biology B, the Salters-Nuffield specification (9BN0). Covers the context-led topics from molecules and the heart to microbiology and ecosystems, how the three written papers are structured and marked, the 18 core practicals, the maths demand, and how to study each topic for top grades.

Browse guides →Syllabus dot points (25)

Edexcel A-Level Biology B (specification 9BN0) is the Salters-Nuffield course: a two-year linear A-level that teaches biology through real contexts and is assessed by three written papers at the end of Year 13. There is no coursework grade; practical work is reported separately as the Science Practical Endorsement. This page is the index: below is a map of the topics, the exam structure, and how to study each one.

The Salters-Nuffield topics

The specification is organised into context-led topics. The earlier topics form the first-year (AS) content; the later topics are second-year A-level content. Each is introduced through a real story or application.

Molecules, diet, transport and health
Carbohydrates, lipids and proteins, the structure and action of the heart and circulation, cardiovascular disease and the role of diet, and gas exchange and transport across cell membranes.
Genes and health
DNA structure and protein synthesis, gene mutation and cystic fibrosis, the structure and action of enzymes, and gene technology, genetic screening and the ethics around them.
The voice of the genome
Cell structure and the cell cycle, meiosis and fertilisation, stem cells and cell differentiation, and the control of gene expression and epigenetics.
Biodiversity and natural resources
Biodiversity and classification, natural selection and adaptation, plant structure and the economic use of plants, and conservation of species and habitats.
Energy, exercise and coordination
Photosynthesis, aerobic and anaerobic respiration, muscles and movement, nervous and hormonal coordination, and homeostasis including the role of the kidney.
Microbiology, immunity and ecosystems
Microorganisms and infectious disease, the immune response and its applications, ecosystems and succession, and populations and sustainability.

Exam structure

Edexcel Biology B is assessed by three written papers, all sat at the end of the course. A calculator is allowed in every paper, and all three papers can draw on any topic.

  • Paper 1 - The natural environment and species survival. 1 hour 45 minutes, 90 marks, 30 per cent. Focuses on the molecules, biodiversity, ecology and energy topics.
  • Paper 2 - Energy, exercise and coordination. 1 hour 45 minutes, 90 marks, 30 per cent. Focuses on respiration, coordination, homeostasis and microbiology.
  • Paper 3 - The challenges of being multicellular. 2 hours 30 minutes, 120 marks, 40 per cent. The synoptic paper, drawing on the whole specification and a pre-released scientific article.

At least 10 per cent of marks assess Level 2 maths skills, and practical skills from the 18 core practicals are tested across all three papers.

How to study Edexcel Biology B

Biology rewards precise definitions, clear application to unfamiliar contexts, and confident data handling.

  1. Work from the specification statements. Each numbered point is a checklist; questions are written from them.
  2. Learn definitions exactly. Mark schemes reward precise wording for terms such as enzyme, allele, biodiversity and homeostasis.
  3. Apply biology to context and data. The papers favour unfamiliar examples, graphs and experiments, so practise reading and explaining them.
  4. Master the core practicals and the maths. The 18 core practicals, statistics such as the chi-squared and t-tests, and rate calculations recur across all three papers.
  5. Rehearse synoptic links and the pre-released article. Paper 3 connects topics; read the article early and research the biology behind it.

Work through the topics

Each topic has an overview guide and a set of dot-point answer pages with worked exam questions and cross-links: molecules, diet, transport and health; genes and health; the voice of the genome; biodiversity and natural resources; energy, exercise and coordination; and microbiology, immunity and ecosystems.

For the official specification

Pearson publishes the full specification (9BN0), past papers and mark schemes at qualifications.pearson.com. Always revise from the current specification and Edexcel's own past papers, because question style is board-specific.

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Common questions about Biology

How is Edexcel A-Level Biology B - Salters-Nuffield (9BN0) structured?
Edexcel A-Level Biology B is a two-year linear course assessed by three written papers at the end of Year 13. It is the Salters-Nuffield specification, which teaches the content through real-life contexts rather than abstract topics first. The content is organised into topics covered across the two years: the AS-level topics run from molecules, diet and transport through to biodiversity, while the second-year topics add energy and coordination, microbiology, immunity and ecosystems. There is no coursework grade, but practical competence is reported separately as the Science Practical Endorsement.
What are the three Edexcel Biology B exam papers?
Paper 1 (The natural environment and species survival) is 1 hour 45 minutes, 90 marks and worth 30 per cent, focusing on the earlier ecology, biodiversity and energy topics. Paper 2 (Energy, exercise and coordination) is also 1 hour 45 minutes, 90 marks and 30 per cent, focusing on the later coordination and homeostasis topics. Paper 3 (The challenges of being multicellular) is 2 hours 30 minutes, 120 marks and worth 40 per cent, and is synoptic, drawing on the whole specification including a pre-released scientific article. All three papers can draw on any topic, so the split is a focus rather than a strict boundary.
What makes the Salters-Nuffield specification different?
Salters-Nuffield (Biology B) is context-led: each topic is introduced through a real story or application, such as a heart attack for the circulation topic, cystic fibrosis for genes and protein synthesis, or coral reefs for biodiversity. The underlying biology assessed is the same as other A-Level Biology specifications, but the teaching order and the contexts are distinctive, and Paper 3 includes a pre-released article that candidates analyse in the exam.
How much maths is in Edexcel Biology B?
At least 10 per cent of the marks across the qualification assess Level 2 (GCSE higher) mathematical skills. Expect ratios, percentages and percentage change, standard form and units, means, medians and modes, simple statistical tests such as the chi-squared test, Spearman's rank and the t-test, calculating rates from graphs, magnification and surface-area-to-volume calculations, and interpreting data and error bars. A calculator is allowed in every paper.
What are the core practicals and the Science Practical Endorsement?
There are 18 core practicals, for example investigating membrane permeability, the effect of enzyme concentration on rate, the rate of dehydrogenase activity in respiration, the effect of temperature on heart rate in Daphnia, and using a transect to study distribution. They are not assessed in a lab exam, but practical skills are tested across the written papers and methods can be examined directly. Separately, your teacher assesses hands-on competence; passing earns the Science Practical Endorsement reported alongside your grade.
How should I study Edexcel Biology B for top grades?
Work topic by topic against the numbered specification statements, because questions are written directly from them. Learn every definition precisely, because mark schemes reward exact wording. Practise applying biology to the unfamiliar contexts and data the papers favour, drill the core-practical methods and the maths and statistics skills, and rehearse the synoptic links Paper 3 demands. Read the pre-released article early and research the biology behind it.
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.