specification overview
Pearson Edexcel International A-Level Biology (YBI11) is a modular qualification made up of 6 units, examined in January, June and October. Units 1-3 form the International AS (IAS); units 4-6 add the International A2 for the full IAL. Practical skills are assessed in dedicated exam papers (Unit 3 at IAS, Unit 6 at IAL), not through a separate endorsement.
specification overview
subject content
1. Molecules, Diet, Transport and Health
Unit 1 (WBI11)- Molecules, transport and health
- Membranes, proteins, DNA and gene expression
2. Cells, Development, Biodiversity and Conservation
Unit 2 (WBI12)- Cell structure, reproduction and development
- Plant structure and function, biodiversity and conservation
3. Practical Skills in Biology I
Unit 3 (WBI13)- Experimental techniques and procedures from units 1 and 2
- Data analysis and evaluation
4. Energy, Environment, Microbiology and Immunity
Unit 4 (WBI14)- Energy flow, ecosystems and the environment
- Microbiology, immunity and forensics
5. Respiration, Internal Environment, Coordination and Gene Technology
Unit 5 (WBI15)- Respiration, muscles and homeostasis
- Coordination, response and gene technology
6. Practical Skills in Biology II
Unit 6 (WBI16)- Experimental techniques and procedures from units 4 and 5
- Advanced data analysis and evaluation
subject content
assessment structure
| Paper | What's assessed | Length | Marks | Weight | Question types |
|---|---|---|---|---|---|
| Unit 1 (WBI11) | Molecules, Diet, Transport and Health | 1h 30m | 80 | 20% IAL / 40% IAS | Multiple-choice, short-open, open-response, calculations and extended writing |
| Unit 2 (WBI12) | Cells, Development, Biodiversity and Conservation | 1h 30m | 80 | 20% IAL / 40% IAS | Multiple-choice, short-open, open-response, calculations and extended writing |
| Unit 3 (WBI13) | Practical Skills in Biology I (units 1-2 techniques) | 1h 20m | 50 | 10% IAL / 20% IAS | Short-open, open-response and calculation questions on practical skills |
| Unit 4 (WBI14) | Energy, Environment, Microbiology and Immunity (may include synoptic content from units 1-2) | 1h 45m | 90 | 20% IAL / 40% IA2 | Multiple-choice, short-open, open-response, calculations and extended writing |
| Unit 5 (WBI15) | Respiration, Internal Environment, Coordination and Gene Technology (may include synoptic content) | 1h 45m | 90 | 20% IAL / 40% IA2 | Multiple-choice, short-open, open-response, calculations and extended writing |
| Unit 6 (WBI16) | Practical Skills in Biology II (units 4-5 techniques) | 1h 20m | 50 | 10% IAL / 20% IA2 | Short-open, open-response and calculation questions on practical skills |
PaperUnit 1 (WBI11)
What's assessedMolecules, Diet, Transport and Health
Length1h 30m
Marks80
Weight20% IAL / 40% IAS
Question typesMultiple-choice, short-open, open-response, calculations and extended writing
PaperUnit 2 (WBI12)
What's assessedCells, Development, Biodiversity and Conservation
Length1h 30m
Marks80
Weight20% IAL / 40% IAS
Question typesMultiple-choice, short-open, open-response, calculations and extended writing
PaperUnit 3 (WBI13)
What's assessedPractical Skills in Biology I (units 1-2 techniques)
Length1h 20m
Marks50
Weight10% IAL / 20% IAS
Question typesShort-open, open-response and calculation questions on practical skills
PaperUnit 4 (WBI14)
What's assessedEnergy, Environment, Microbiology and Immunity (may include synoptic content from units 1-2)
Length1h 45m
Marks90
Weight20% IAL / 40% IA2
Question typesMultiple-choice, short-open, open-response, calculations and extended writing
PaperUnit 5 (WBI15)
What's assessedRespiration, Internal Environment, Coordination and Gene Technology (may include synoptic content)
Length1h 45m
Marks90
Weight20% IAL / 40% IA2
Question typesMultiple-choice, short-open, open-response, calculations and extended writing
PaperUnit 6 (WBI16)
What's assessedPractical Skills in Biology II (units 4-5 techniques)
Length1h 20m
Marks50
Weight10% IAL / 20% IA2
Question typesShort-open, open-response and calculation questions on practical skills
The qualification is modular. Papers are available in January, June and October each year, so units can be sat in stages. The IAS is claimed on completion of units 1-3; the full IAL on completion of all six.
assessment structure
assessment objectives
| AO | What it means | Overall |
|---|---|---|
| AO1 | Demonstrate knowledge and understanding of science. | 34-37% |
| AO2(a) | Application of knowledge and understanding of science in familiar and unfamiliar contexts. | 33-36% |
| AO2(b) | Analysis and evaluation of scientific information to make judgements and reach conclusions. | 11-14% |
| AO3 | Experimental skills in science, including analysis and evaluation of data and methods. | 17-18% |
AOAO1
What it meansDemonstrate knowledge and understanding of science.
Overall34-37%
AOAO2(a)
What it meansApplication of knowledge and understanding of science in familiar and unfamiliar contexts.
Overall33-36%
AOAO2(b)
What it meansAnalysis and evaluation of scientific information to make judgements and reach conclusions.
Overall11-14%
AOAO3
What it meansExperimental skills in science, including analysis and evaluation of data and methods.
Overall17-18%
assessment objectives
required practicals
| Practical | What it involves |
|---|---|
| CP1 Use a semi-quantitative method with Benedict's reagent to estimate the concentrations of reducing sugars and with iodine solution to estimate the concentrations of starch, using colour standards. | – |
| CP2 Investigate the vitamin C content of food and drink. | – |
| CP3 Investigate membrane properties including the effect of alcohol and temperature on membrane permeability. | – |
| CP4 Investigate the effect of temperature, pH, enzyme concentration and substrate concentration on the initial rate of enzyme-catalysed reactions. | – |
| CP5 Use a light microscope to make observations and labelled drawings of suitable animal cells, and use a graticule with a microscope to make measurements and understand the concept of scale. | – |
| CP6 Prepare and stain a root tip squash to observe the stages of mitosis. | – |
| CP7 Use a light microscope to make observations, draw and label plan diagrams of transverse sections of roots, stems and leaves; observe and draw cells of plant tissues; and identify sclerenchyma fibres, phloem, sieve tubes and xylem vessels and their location. | – |
| CP8 Determine the tensile strength of plant fibres. | – |
| CP9 Investigate the antimicrobial properties of plants, including aseptic techniques for the safe handling of bacteria. | – |
| CP10 Investigate the effects of light intensity, light wavelength, temperature and availability of carbon dioxide on the rate of photosynthesis using a suitable aquatic plant. | – |
| CP11 Carry out a study of the ecology of a habitat, such as using quadrats and transects to determine the distribution and abundance of organisms, and measuring abiotic factors appropriate to the habitat. | – |
| CP12 Investigate the effects of temperature on the development of organisms (such as seedling growth rate or brine shrimp hatch rates), taking into account the ethical use of organisms. | – |
| CP13 Investigate the rate of growth of microorganisms in a liquid culture, taking into account the safe and ethical use of organisms. | – |
| CP14 Investigate the effect of different antibiotics on bacteria. | – |
| CP15 Use an artificial hydrogen carrier (redox indicator) to investigate respiration in yeast. | – |
| CP16 Use a simple respirometer to determine the rate of respiration and RQ of a suitable material (such as germinating seeds or small invertebrates). | – |
| CP17 Investigate the effects of exercise on tidal volume, breathing rate, respiratory minute ventilation, and oxygen consumption using data from spirometer traces. | – |
| CP18 Investigate the production of amylase in germinating cereal grains. | – |
PracticalCP1 Use a semi-quantitative method with Benedict's reagent to estimate the concentrations of reducing sugars and with iodine solution to estimate the concentrations of starch, using colour standards.
What it involves–
PracticalCP2 Investigate the vitamin C content of food and drink.
What it involves–
PracticalCP3 Investigate membrane properties including the effect of alcohol and temperature on membrane permeability.
What it involves–
PracticalCP4 Investigate the effect of temperature, pH, enzyme concentration and substrate concentration on the initial rate of enzyme-catalysed reactions.
What it involves–
PracticalCP5 Use a light microscope to make observations and labelled drawings of suitable animal cells, and use a graticule with a microscope to make measurements and understand the concept of scale.
What it involves–
PracticalCP6 Prepare and stain a root tip squash to observe the stages of mitosis.
What it involves–
PracticalCP7 Use a light microscope to make observations, draw and label plan diagrams of transverse sections of roots, stems and leaves; observe and draw cells of plant tissues; and identify sclerenchyma fibres, phloem, sieve tubes and xylem vessels and their location.
What it involves–
PracticalCP8 Determine the tensile strength of plant fibres.
What it involves–
PracticalCP9 Investigate the antimicrobial properties of plants, including aseptic techniques for the safe handling of bacteria.
What it involves–
PracticalCP10 Investigate the effects of light intensity, light wavelength, temperature and availability of carbon dioxide on the rate of photosynthesis using a suitable aquatic plant.
What it involves–
PracticalCP11 Carry out a study of the ecology of a habitat, such as using quadrats and transects to determine the distribution and abundance of organisms, and measuring abiotic factors appropriate to the habitat.
What it involves–
PracticalCP12 Investigate the effects of temperature on the development of organisms (such as seedling growth rate or brine shrimp hatch rates), taking into account the ethical use of organisms.
What it involves–
PracticalCP13 Investigate the rate of growth of microorganisms in a liquid culture, taking into account the safe and ethical use of organisms.
What it involves–
PracticalCP14 Investigate the effect of different antibiotics on bacteria.
What it involves–
PracticalCP15 Use an artificial hydrogen carrier (redox indicator) to investigate respiration in yeast.
What it involves–
PracticalCP16 Use a simple respirometer to determine the rate of respiration and RQ of a suitable material (such as germinating seeds or small invertebrates).
What it involves–
PracticalCP17 Investigate the effects of exercise on tidal volume, breathing rate, respiratory minute ventilation, and oxygen consumption using data from spirometer traces.
What it involves–
PracticalCP18 Investigate the production of amylase in germinating cereal grains.
What it involves–
required practicals
key tips for success
Plan your unit staging early
The modular structure means you can sit units in January, June or October. Decide with your school which units go in which series so you're not cramming five theory units at once.
Prepare specifically for Units 3 and 6
The practical-skills papers are worth 20% of the IAL combined and test techniques from the preceding theory units. Practise experimental design, data analysis and evaluation using unfamiliar contexts.
Expect synoptic questions on Units 4 and 5
Later units can pull knowledge from earlier ones. Revise units 1-2 before sitting Units 4 and 5, not just the newer content.
Build maths fluency
Each theory paper carries maths marks at Level 2 or above. Practise data-handling, rates, biological indices and statistical tests.
Know the difference between IAS and IAL
Units 1-3 make up the International Advanced Subsidiary (IAS), a standalone qualification. Adding units 4-6 gives you the full IAL. Some students take just the IAS.
Use past papers series-by-series
With three exam series a year, there's a large past-paper archive. Use them to time yourself under exam conditions, especially for the practical-skills papers.
key tips for success
Where to next
Start your learning journey today...
Practise with Cognito's free past papers for this spec – or browse grade boundaries and related specifications.
Where to next
