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OCR A-level Biology A PAGs: all 12

OCR does not number individual practicals. It sorts the practical work for the endorsement into twelve practical activity groups (PAGs), each a set of techniques, and gives one example activity per group, which your school may replace with another.

From the OCR Biology A specification, version 4.1 (April 2026).

For each group you will find OCR’s name for it and its example activity, with the lesson sections that teach methods using those techniques. Where we do not teach a group yet, we say so.

Number	Practical activity group, in OCR’s words	Where the method is taught
PAG1	Microscopy OCR’s example activity: Using a light microscope to study mitosis	Required practical 2: root tip squash and mitotic index, the full practical guide Prepare a stained root tip squash and calculate a mitotic index, in the lesson The cell cycle and mitosis Calibrate a graticule against a stage micrometer and measure a cell, in the lesson Microscopy, magnification and resolution OCR’s example is the root tip squash, the first link.
PAG2	Dissection OCR’s example activity: Dissection of the mammalian heart	Required practical 5: dissecting an insect and a fish gill, the full practical guide Dissect an insect's tracheal system and a fish gill, and draw them, in the lesson Gas exchange in insects, fish and plants OCR’s example, the mammalian heart, is not written up here. The insect and fish gill dissection uses the same instruments and drawing.
PAG3	Sampling techniques OCR’s example activity: The calculation of species diversity	Required practical 12: a belt transect and species distribution, the full practical guide Sample with quadrats and transects and relate distribution to an abiotic factor, in the lesson Succession and environmental change Estimate a population of mobile animals by mark, release and recapture, in the lesson Populations and their limits OCR’s example, calculating species diversity, is worked in the lesson on measuring biodiversity, under Simpson’s index.
PAG4	Rates of enzyme controlled reactions OCR’s example activity: The effect of substrate concentration on the rate of an enzyme controlled reaction	Required practical 1: enzyme rate with trypsin and milk, the full practical guide Measure the rate of an enzyme-controlled reaction, in the lesson Factors affecting enzyme rate: temperature, pH and concentration Draw a tangent for initial rate and calculate Q10, in the lesson Factors affecting enzyme rate: temperature, pH and concentration
PAG5	Colorimeter or potometer OCR’s example activity: The effect of temperature on membrane permeability	Required practical 11: glucose concentration by colorimetry, the full practical guide Required practical 4: beetroot membranes and temperature, the full practical guide Measure membrane permeability with beetroot and a colorimeter, in the lesson Membrane structure and the fluid mosaic model Measure the rate of water uptake with a potometer, in the lesson Xylem and the transpiration stream Find a glucose concentration from a colorimeter calibration curve, in the lesson Carbohydrate structure and function
PAG6	Chromatography OR electrophoresis OCR’s example activity: Identification of the amino acids in a protein using paper chromatography	Required practical 7: chromatography of leaf pigments, the full practical guide Separate photosynthetic pigments by chromatography and find Rf values, in the lesson Chloroplast structure and the light-dependent reactions Separate DNA fragments by gel electrophoresis, in the lesson Recombinant DNA technology OCR’s example separates amino acids by paper chromatography, which is not written up. The method and the Rf calculation are the same as for leaf pigments.
PAG7	Microbiological techniques OCR’s example activity: The effect of antibiotics on bacterial growth	Required practical 6: aseptic technique and antibiotic discs, the full practical guide Compare antibiotics by their zones of inhibition, in the lesson Evidence for evolution, resistance and genetic drift Test plant extracts against bacteria on agar, aseptically, in the lesson Industrial biotechnology and fermentation Isolate single colonies by streak plating, in the lesson Industrial biotechnology and fermentation Follow the growth of a bacterial culture by turbidity or counts, in the lesson Industrial biotechnology and fermentation OCR’s example, antibiotics and bacterial growth, is the first link.
PAG8	Transport in and out of cells OCR’s example activity: An investigation into the water potential of potato	Required practical 3: water potential of potato tissue, the full practical guide Find the water potential of potato tissue from a dilution series, in the lesson Diffusion and osmosis
PAG9	Qualitative testing OCR’s example activity: Qualitative testing for biological molecules – proteins	Test for protein with biuret reagent, in the lesson Protein structure and function Test for reducing sugars, non-reducing sugars and starch, in the lesson Carbohydrate structure and function Test for lipids with ethanol and water, in the lesson Lipids: triglycerides, phospholipids and ester bonds
PAG10	Investigation using a data logger OR computer modelling OCR’s example activity: Investigating DNA structure using RasMol	Not written up here yet. Nothing here teaches data logging or computer modelling as a method yet, and OCR’s example, DNA structure in RasMol, is not covered.
PAG11	Investigation into the measurement of plant or animal responses OCR’s example activity: Investigation into the effect of exercise on pulse rate	Required practical 10: woodlice in a choice chamber, the full practical guide Read tidal volume, breathing rate and oxygen uptake from a spirometer trace, in the lesson Gas exchange in mammals: lungs and ventilation Measure the effect of caffeine on the heart rate of Daphnia, in the lesson Variables and controls: what an experiment can show Investigate an animal's response to light or humidity in a choice chamber, in the lesson Receptors: transduction and the reflex arc Measure habituation in snails to a repeated touch, in the lesson Brain imaging, development and learning OCR’s example is exercise and pulse rate. The spirometer section measures the effect of exercise on breathing instead.
PAG12	Research skills OCR’s example activity: Investigation into the respiration rate of Saccharomyces cerevisiae	Required practical 9: respiration rate in yeast, the full practical guide Measure the rate of respiration in yeast with methylene blue, in the lesson Anaerobic respiration and the respiratory quotient OCR’s example, the respiration rate of yeast, is this section. The research and referencing skills the group assesses are not taught as a method here.

To see the same methods by technique, with their calculations and the errors to avoid, go to A-level Biology practicals.

To find the lessons that teach each numbered statement of this specification, use the OCR A route map.

Your school picks the activities for each group. OCR’s specification and practical guidance set the rules for that choice and for how the Practical Endorsement is assessed.

List checked against the specification on 23 October 2026.