Current syllabus · first assessment 2019

A-Level Biology AS Study Guide & Review

Study Pearson Edexcel International AS Biology by linking molecular and cellular mechanisms to unfamiliar evidence, nine core practicals and precise mathematical and data reasoning across Units 1–3.

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  1. 01Learn concepts
  2. 02Practise questions
  3. 03Review mistakes

How to study Pearson Edexcel International AS Biology

Pearson Edexcel IAS Biology rewards more than accurate recall. Use the IAS syllabus map to connect Units 1–2 mechanisms with nine core practicals and the mathematical skills assessed across all three units. For every Topic, explain the causal biological sequence, interpret unfamiliar tables, images or claims, show calculations with units and significant figures, and decide what the evidence supports rather than repeating a memorised conclusion.

Rebuild the mechanism or investigation logic in Concept and retrieve key terms, sequences, variables and quantitative relationships in Mastery without copying notes. Apply them through the Question Bank and label the first failure as mechanism, stimulus interpretation, calculation, evidence judgement or practical design. Repair that step and retry a nearby question, carrying the same practical and data habits into the written Unit 3 examination.

Practise IAS Biology by evidence and mechanism

Use distinct routines for molecular health evidence, membranes and gene expression, cell development, biodiversity decisions and written practical-data analysis.

Molecules, transport and health evidence

Water, carbohydrates, lipids, circulation, haemoglobin, cardiovascular risk and diet

Link molecular structure to transport or physiological function before using it to explain health. For risk evidence, distinguish correlation from causation, inspect sample and design limits, calculate changes with units and finish with a conclusion no stronger than the data support.

Practise Topic 1

Membranes, enzymes and gene expression

Membrane transport, proteins, initial rates, DNA, transcription, translation and mutation

Draw or narrate the mechanism in order, name the structure responsible at each step and predict how one changed condition alters the outcome. For enzyme and membrane data, identify variables, calculate rates or percentage change and link the pattern back to molecular interactions.

Practise Topic 2

Cells, reproduction and development

Microscopy, ultrastructure, mitosis, meiosis, fertilisation, stem cells and epigenetics

Move between image, scale and biological process: identify visible evidence, calculate magnification or size with converted units, then explain how chromosome or gene-expression changes produce the observed developmental outcome. Compare processes through one shared feature rather than listing disconnected facts.

Practise Topic 3

Plants, biodiversity and conservation

Plant tissues, fibres, antimicrobials, classification, biodiversity measures and conservation evidence

Connect plant structure to function and the practical method that tests it. For biodiversity or conservation claims, identify the measure, sampling decision and competing evidence, process the data accurately and make a justified decision that recognises uncertainty and trade-offs.

Practise Topic 4

Unit 3 practical and data reasoning

Variables, apparatus, safety, repeats, tables, graphs, gradients, uncertainty and improvements

Reconstruct each of the nine IAS core practicals through its biological purpose, variables, apparatus, controls, safety and expected data. Practise choosing scales, plotting and interpreting graphs, carrying units and significant figures, identifying specific error and pairing each limitation with a realistic improvement.

Practise Unit 3

Where to start

Start from a known Unit Topic or diagnose whether the recurring weakness is biological explanation, unfamiliar application, mathematics, evidence judgement or practical reasoning.

Choose your starting point

  1. I know the weak Topic

    Open the exact Unit, practical or mathematics destination and identify the failed mechanism, evidence, calculation or investigation decision.

    Browse the IAS units

  2. I do not know what is weak

    Use mixed questions from WBI11–WBI13 to separate recall gaps from unfamiliar application, data handling and practical-method failures.

    Start a diagnostic

Choose the right IAS Biology starting point

  1. Explain the mechanism

    Reconstruct the biological sequence, structures and causal links, then connect them to the relevant practical or quantitative evidence.

    Review a Concept

  2. Retrieve evidence and variables

    Reproduce key terminology, process order, practical variables, controls, units and mathematical relationships without notes.

    Check Mastery

  3. Apply and repair

    Answer an unfamiliar stimulus or practical question, identify the first unsupported step and retry with the corrected biological reasoning.

    Practise questions

Explore the Pearson Edexcel IAS Biology units

Navigate four theory Topics across Units 1–2, the written Unit 3 practical-skills destination and five assessed mathematics and measurement areas. The 4-group, 10-Topic map keeps XBI11 content bounded to IAS while connecting nine core practicals and quantitative reasoning to every Unit.

4
syllabus groups
10
mapped topics

Unit 1: Molecules, Diet, Transport and Health

Open unit questions
Topic 1 - Molecules, Transport and HealthTopic 2 - Membranes, Proteins, DNA and Gene Expression

Unit 2: Cells, Development, Biodiversity and Conservation

Open unit questions
Topic 3 - Cell Structure, Reproduction and DevelopmentTopic 4 - Plant Structure and Function, Biodiversity and Conservation

Unit 3: Practical Skills in Biology I

Open unit questions
Practical Skills in Biology I

Assessed mathematical skills and measurement conventions

Open unit questions
A.0 Arithmetic and numerical computationA.1 Handling dataA.2 AlgebraA.3 GraphsA.4 Geometry and trigonometry

Pearson Edexcel International AS Biology assessment

IAS consists of three externally assessed written units. WBI11 and WBI12 each contribute 40%, while WBI13 contributes 20% through practical and investigative reasoning developed from the nine core practicals in Units 1–2.

Paper / componentQuestionsTime% of grade
Unit 1 Molecules, Diet, Transport and Health (WBI11/01)Multiple-choice, short-open, open-response, calculations and extended writing80 marksCandidates answer all questions in familiar and unfamiliar contexts across Topics 1–2. The paper includes at least 8 marks of Level 2-or-above mathematics.How to prepare: Combine exact molecular mechanisms with unfamiliar health evidence. Practise calculations, unit conversions and data interpretation alongside causal explanations, and judge correlation, study design and treatment claims from the evidence supplied rather than memorised health conclusions.1 hour 30 minutes40% of IAS
Unit 2 Cells, Development, Biodiversity and Conservation (WBI12/01)Multiple-choice, short-open, open-response, calculations and extended writing80 marksCandidates answer all questions in familiar and unfamiliar contexts across Topics 3–4. The paper includes at least 8 marks of Level 2-or-above mathematics.How to prepare: Practise microscopy and image interpretation, biological comparisons, development mechanisms, sampling and data analysis. Make conservation judgements from competing evidence and show magnification, graph, percentage and statistical working with appropriate units and precision.1 hour 30 minutes40% of IAS
Unit 3 Practical Skills in Biology I (WBI13/01)Short-open, open-response and calculation questions50 marksThis external written paper applies practical and investigative knowledge from Units 1–2 to familiar and unfamiliar situations. Candidates answer all questions, including at least 5 marks of Level 2-or-above mathematics.How to prepare: Reconstruct the nine IAS core practicals as decisions: purpose, variables, controls, apparatus, safety, repeats, tables, graphs, uncertainty, conclusions and improvements. Practise unfamiliar methods and data in writing; Unit 3 is not a live bench examination.1 hour 20 minutes20% of IAS

SourcePearson Edexcel · International Advanced Level Biology SpecificationXBI11 · Issue 2 · February 2021

Pearson Edexcel International AS Biology questions

The XBI11 IAS qualification consists of Unit 1 WBI11, Unit 2 WBI12 and Unit 3 WBI13. Units 1–2 cover four theory Topics and nine IAS core practicals; Unit 3 assesses the practical and investigative skills developed through them. IA2 Units 4–6 do not belong to this AS Course.

No. Unit 3 is an externally assessed written paper lasting 1 hour 20 minutes. It tests practical knowledge, planning, variables, apparatus, safety, data presentation, uncertainty, conclusions, evaluation and improvements in familiar or unfamiliar situations. Real practical experience remains important preparation even though the examination itself is written.

Use the 40:40:20 weighting as a starting point, not a rigid timetable. Units 1 and 2 need broad Topic coverage and unfamiliar application, while practical and mathematical reasoning should run through all study because WBI13 draws on both units. Let diagnostic evidence increase time on the weakest mechanism or skill.

Yes. XBI11 can be awarded as a standalone International AS qualification or contribute 50% towards the full YBI11 International A Level. The complete IAL requires all six units, adding IA2 Units 4–6. Only Units 1–3 contribute to the IAS grade.