In short
Edexcel IAL Biology (YBI11) is a modular International A Level made of six written exams. The International AS (XBI11) is Units 1 to 3 and counts for half; Units 4 to 6 complete the full A level. Units 3 and 6 test the 18 core practicals. Exams run in January, June and October, and any unit can be resat.
Pearson Edexcel International A Level Biology (cash-in code YBI11) is a modular A level made of six units, all of them written exams. The first three units make up the International AS Level (XBI11), which can be a qualification on its own or count for 50% of the full International A Level. Units 3 and 6 are practical skills papers based on 18 core practicals. Every unit is available in January, June and October, and you can resit any unit.
Every fact below comes from the official Pearson specification (Issue 2, February 2021). Our free notes for the course are on the Edexcel International A Level Biology course page, and the AS content on its own is on the Edexcel International AS Biology page.
What is Edexcel IAL Biology?
IAL stands for International Advanced Level. The specification uses three abbreviations you will see everywhere: IAS (International Advanced Subsidiary, the first half), IA2 (International A2, "the additional content required for an IAL") and IAL (the full International Advanced Level). It is an international qualification: assessment is "available in English only", the exams run three times a year, and you build the qualification from separate unit exams.
The specification says a school can teach the course as "distinct modules of teaching and learning with related units of assessment taken at appropriate stages during the course", or as "a linear course assessed in its entirety at the end". In practice this means you might sit Units 1 and 2 in your first year, or save everything for the end. Your school decides the order with you.
Pearson has announced a redeveloped International Advanced Level Biology (2027), with teaching from September 2027 and first IAS certification in August 2028. This guide covers the current 2018 specification (XBI11/YBI11). Pearson has not yet said when the last exams for the 2018 units will be, so check with your school which specification you are on.
Edexcel IAS Biology vs the full International A Level
The specification puts it simply: "The International Advanced Subsidiary (IAS) is the first half of the International Advanced Level qualification and consists of three IAS units, units 1, 2 and 3." To get the full International A Level, "candidates ... must ... complete all six units": the three IAS units plus the three IA2 units (Units 4, 5 and 6).
- International AS Biology (XBI11): Units 1, 2 and 3, covering Topics 1 to 4 and core practicals 1 to 9. Graded A to E.
- International A Level Biology (YBI11): all six units, covering Topics 1 to 8 and all 18 core practicals. Graded A* to E.
- "Only units 1, 2 and 3 will contribute to the International Advanced Subsidiary grade. All six units will contribute to the International Advanced Level grade."
The six Edexcel International A Level Biology units
Every paper is a written exam and in every paper "candidates must answer all questions". There is no coursework. Here are the six units, with their entry codes, timings, marks and weightings from the specification.
| Unit | Code | Level | Topics | Time | Marks | Weighting |
|---|---|---|---|---|---|---|
| Unit 1: Molecules, Diet, Transport and Health | WBI11/01 | IAS | Topics 1 and 2 | 1 h 30 min | 80 | 40% of IAS; 20% of IAL |
| Unit 2: Cells, Development, Biodiversity and Conservation | WBI12/01 | IAS | Topics 3 and 4 | 1 h 30 min | 80 | 40% of IAS; 20% of IAL |
| Unit 3: Practical Skills in Biology I | WBI13/01 | IAS | Practical skills from Units 1 and 2 (core practicals 1 to 9) | 1 h 20 min | 50 | 20% of IAS; 10% of IAL |
| Unit 4: Energy, Environment, Microbiology and Immunity | WBI14/01 | IA2 | Topics 5 and 6 | 1 h 45 min | 90 | 40% of IA2; 20% of IAL |
| Unit 5: Respiration, Internal Environment, Coordination and Gene Technology | WBI15/01 | IA2 | Topics 7 and 8 | 1 h 45 min | 90 | 40% of IA2; 20% of IAL |
| Unit 6: Practical Skills in Biology II | WBI16/01 | IA2 | Practical skills from Units 1, 2, 4 and 5 (core practicals 1 to 18) | 1 h 20 min | 50 | 20% of IA2; 10% of IAL |
Adding the marks up, the IAS papers total 210 raw marks and the full A level 440. Units 1, 2, 4 and 5 "may include multiple-choice, short-open, open-response, calculations and extended-writing questions". Units 3 and 6 "may include short-open, open-response and calculation questions". The specification does not say how many questions of each type a paper has, so look at past papers to see typical layouts.
IAL Biology Unit 1
Unit 1 (WBI11/01) is the first unit most students meet. It covers Topic 1, Molecules, Transport and Health, and Topic 2, Membranes, Proteins, DNA and Gene Expression: water, carbohydrates, lipids, proteins and nucleic acids, diet and the cardiovascular system, membrane transport, enzymes, protein synthesis, mutations and genetic screening. It is 1 hour 30 minutes, 80 marks, with at least 8 marks for maths at Level 2 or above.
Synoptic questions and the Unit 5 pre-release
Units 4 and 5 "may contain some synoptic questions which require knowledge and understanding from units 1 and 2", and Unit 6 "will include synoptic questions that may draw on all topics". So you cannot forget your AS biology once those exams are done. Unit 5 also has a pre-released scientific article: it "will underpin one question of the paper. This question carries 20 marks." The specification does not say how far ahead it is released, so check Pearson's notice for your series.
The 8 topics and which unit examines each
Each theory unit examines two topics. Use the links to go straight to our notes for that topic.
| Topic | Unit | Level |
|---|---|---|
| Topic 1: Molecules, Transport and Health | Unit 1 | IAS |
| Topic 2: Membranes, Proteins, DNA and Gene Expression | Unit 1 | IAS |
| Topic 3: Cell Structure, Reproduction and Development | Unit 2 | IAS |
| Topic 4: Plant Structure and Function, Biodiversity and Conservation | Unit 2 | IAS |
| Topic 5: Energy Flow, Ecosystems and the Environment | Unit 4 | IA2 |
| Topic 6: Microbiology, Immunity and Forensics | Unit 4 | IA2 |
| Topic 7: Respiration, Muscles and the Internal Environment | Unit 5 | IA2 |
| Topic 8: Coordination, Response and Gene Technology | Unit 5 | IA2 |
There are 170 numbered specification statements in total: 80 for the IAS and 90 for the IA2. Tick them off as you go with the IAL specification checklist.
IAL Biology core practicals
The specification lists 18 core practicals, which it calls "the minimum number of practical activities that students will carry out". They are not marked as coursework. Instead, questions in the exams "assess the knowledge and understanding that students gain while carrying out practical activities, within the context of the 18 core practical activities, as well as in novel practical scenarios". Core practicals 1 to 9 belong to the IAS and 10 to 18 to the IA2.
| CP | Spec | Unit | Core practical |
|---|---|---|---|
| 1 | 1.3 | 1 | Benedict's reagent and iodine solution with colour standards to estimate reducing sugar and starch concentrations |
| 2 | 1.14 | 1 | Investigate the vitamin C content of food and drink |
| 3 | 2.3 | 1 | Membrane permeability, including the effect of alcohol and temperature |
| 4 | 2.8 | 1 | Effect of temperature, pH, enzyme concentration and substrate concentration on the initial rate of enzyme-catalysed reactions |
| 5 | 3.8 | 2 | Light microscope drawings of animal cells, and measuring with a graticule |
| 6 | 3.15 | 2 | Prepare and stain a root tip squash to observe the stages of mitosis |
| 7 | 4.6 | 2 | Light microscope plan diagrams of roots, stems and leaves; identify sclerenchyma, phloem, sieve tubes and xylem |
| 8 | 4.9 | 2 | Determine the tensile strength of plant fibres |
| 9 | 4.12 | 2 | Antimicrobial properties of plants, including aseptic techniques |
| 10 | 5.8 | 4 | Effect of light intensity, wavelength, temperature and carbon dioxide on the rate of photosynthesis in an aquatic plant |
| 11 | 5.14 | 4 | Ecology of a habitat, using quadrats and transects and measuring abiotic factors |
| 12 | 5.22 | 4 | Effect of temperature on the development of organisms, such as seedling growth or brine shrimp hatch rates |
| 13 | 6.4 | 4 | Rate of growth of microorganisms in a liquid culture |
| 14 | 6.14 | 4 | Effect of different antibiotics on bacteria |
| 15 | 7.7 | 5 | Artificial hydrogen carrier (redox indicator) to investigate respiration in yeast |
| 16 | 7.8 | 5 | Simple respirometer to find the rate of respiration and RQ |
| 17 | 7.15 | 5 | Effects of exercise on tidal volume, breathing rate, minute ventilation and oxygen consumption from spirometer traces |
| 18 | 8.12 | 5 | Production of amylase in germinating cereal grains |
What Units 3 and 6 test
Both practical papers test the same list of skills: solving problems in practical contexts, commenting on experimental design, presenting data, identifying variables, plotting and interpreting graphs, processing data with maths, using apparatus safely, evaluating results with reference to uncertainties and errors, and planning an investigation to test a hypothesis. Unit 3 is based on the practicals in Units 1 and 2. Unit 6 is based on all of them, and its planning list adds a null hypothesis, calibrating instruments and ethical issues in using living organisms. Its analysis list says a graph "could be logarithmic".
For every core practical, be ready to write the method, name the independent, dependent and control variables, state a safety point, and suggest how to reduce error. Planning questions often swap in a new organism or variable, so learn the reasoning, not just the steps.
All the experimental skills (AO3) marks are in Units 3 and 6, which together are 20% of the full A level. The theory papers carry no AO3 marks, but they still test the biology behind the practicals.
Exam series, resits and the modular structure
The specification says: "From June 2020, all six units will be assessed in January, June and October for the lifetime of the qualification", and IAS and IAL are both awarded in each of those series. Individual unit results are reported, so you see your result for each unit as you go.
On resits: "Candidates can resit any unit irrespective of whether the qualification is to be cashed in. If a candidate resits a unit more than once, only the better of the two most recent attempts of that unit will be available for aggregation to a qualification grade." So a weaker Unit 1 result can be improved in a later series, but be careful about sitting the same unit three or more times: your first attempt drops out of the calculation.
How IAL Biology is graded
Each unit's raw mark is turned into a uniform mark (UMS), and the uniform marks are added to give your grade. The IAS is graded A to E and the IAL A* to E. Raw mark grade boundaries change every series and Pearson publishes them separately; the uniform mark scale below is fixed in the specification.
| Max UMS | A | B | C | D | E | |
|---|---|---|---|---|---|---|
| Units 1, 2, 4, 5 (each) | 120 | 96 | 84 | 72 | 60 | 48 |
| Units 3, 6 (each) | 60 | 48 | 42 | 36 | 30 | 24 |
| International AS (XBI11) | 300 | 240 | 210 | 180 | 150 | 120 |
| International A Level (YBI11) | 600 | 480 | 420 | 360 | 300 | 240 |
To get an A*, you need an A overall (at least 480 uniform marks) and "at least 90 percent of the total uniform marks available across the IA2 units combined (at least 270 uniform marks)". In other words, a strong AS cannot carry you to an A* on its own: Units 4, 5 and 6 decide it.
At least 10% of the marks across the papers are for maths at Level 2 or above. Three maths skills are tested only in the full A level: using calculators for powers, exponentials and logarithms, using logarithms for quantities that range over several orders of magnitude, and finding the intercept of a graph.
How it compares with a UK A level
Both lead to an A level in Biology, but the assessment works differently. Taking AQA A-level Biology (7402) as an example of a UK A level:
| Edexcel IAL Biology (YBI11) | AQA A-level Biology (7402) | |
|---|---|---|
| Structure | Modular: six unit exams, can be sat across different series | Linear: all exams in May/June of a single year |
| Does the AS count? | Yes: the IAS is 50% of the IAL | No: the A level is three papers covering all eight topics |
| Exam series | January, June and October | May/June |
| Practical assessment | Two written practical skills papers (Units 3 and 6) | Practical questions in the written papers, plus a separately reported practical endorsement assessed by teachers |
| Grades | A* to E (IAS A to E) | A* to E |
Other UK boards differ in the detail, so compare your own board's specification. If you are choosing between courses, ask your school which one it offers and which suits your exam timeline.
A revision plan for Edexcel IAL Biology
- Find out your exam plan. Ask your school which units you are sitting in which series (January, June or October), and whether you are on the 2018 specification.
- Learn one unit at a time. Work through the two topics for your next theory unit using our revision notes, starting with Topic 1 and Topic 2 for Unit 1. For the AS only, use the International AS course.
- Tick off the specification. Every statement can be examined. Use the specification checklist so nothing is missed.
- Revise each core practical as you meet it. Write a short method, variables, risks and errors for each one in the table above. Unit 3 and Unit 6 marks come from this.
- Practise questions. Use our IAL exam questions and flashcards little and often, and learn the command words ("explain" needs a reason; "calculate" needs working and the unit).
- Keep the AS fresh for A2. Units 4 and 5 may include synoptic questions on Units 1 and 2, and Unit 6 can draw on all topics, so revisit your AS notes during the second year.
- Finish with past papers. Sit full, timed papers and mark them with the official mark schemes. Our IAL past papers page links to Pearson's official materials.
Our guide to how IGCSE Biology is marked explains mark schemes and command words, and the same habits carry straight over to the IAL papers. If you want help with a particular unit or with the practical papers, we offer 1-to-1 biology tutoring online and in Dubai.
Sources: Pearson Edexcel International AS/A Level Biology specification, Issue 2, the Pearson IAL Biology (2018) qualification page, the Pearson IAL Biology (2027) qualification page and the AQA AS and A-level Biology specification.