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The practical map
Ten practical activities, five topic homes and one repeatable way to think: identify what changes or is compared, what you observe or measure, and what keeps the evidence valid.
- 1MicroscopyTrilogy 1
- 2Antibiotics & antisepticsSeparate
- 3OsmosisTrilogy 2
- 4Food testsTrilogy 3
- 5Amylase & pHTrilogy 4
- 6PhotosynthesisTrilogy 5
- 7Reaction timeTrilogy 6
- 8Seedling responsesSeparate
- 9Field samplingTrilogy 7
- 10Milk decaySeparate
Showing 10 practicals
Microscopy
A microscope makes cells look larger; the scale proves you know what ‘larger’ means.
- Question
- Prepare, observe, draw and label plant and animal cells using a light microscope, including a magnification scale.
- Change or compare
- type of prepared cell specimen or magnification being compared
- Measure or observe
- structures resolved and measurements made in the microscope image
Open the exam playbook
Method in beats
- Place a thin specimen on a clean slide; add a suitable stain if instructed, then lower a coverslip at an angle to reduce trapped air bubbles.
- Put the slide on the stage and begin with the lowest-power objective lens.
- Use the coarse focus to find the specimen, then sharpen it with fine focus; use fine focus only at high power.
- Centre the specimen before changing to a higher-power objective and adjust the light if needed.
- Draw several representative cells using clear single lines, add labels and include a scale or calculated magnification.
- Repeat with the other specimen type and compare visible structures.
Control
- specimen thickness and preparation method
- stain identity and amount
- lighting and focus procedure
- calibrated scale or the same image-measurement method
Graph or record
Usually no graph: the evidence is a clear biological drawing, labels and a meaningful magnification scale.
Calculation
Total magnification = eyepiece magnification × objective magnification. Use a scale bar to estimate real size.
Safety cue
- Wear eye protection when using stains and avoid skin contact; follow the school's reagent guidance.
- Handle glass slides and coverslips by their edges and report chips or breakages.
- Carry the microscope with two hands and keep it away from the bench edge.
Classic trap
Drawing artistic shading or labelling structures that the image does not actually resolve.
Revise it inside Cell Biology – AQA GCSE Biology Revision Guide →
Antibiotics & antiseptics
Bacteria do not read the disc label. The clear zone is the evidence.
- Question
- Use aseptic technique to compare how antibiotics or antiseptics affect bacterial growth on agar by measuring clear zones of inhibition.
- Change or compare
- identity or concentration of the antibiotic or antiseptic on each disc
- Measure or observe
- mean diameter or calculated area of the clear zone around the disc
Open the exam playbook
Method in beats
- Disinfect the bench, wash hands and label the base of a sterile agar plate before inoculation.
- Sterilise the inoculating loop in a flame as instructed, let it cool, then use it to spread the bacterial culture evenly across the agar.
- Open the lid only slightly and briefly; place sterile treatment discs on the agar with sterile forceps.
- Include a control disc carrying only the solvent, then replace the lid promptly.
- Tape the lid in a few places without sealing all the way around, invert the plate and incubate at no more than 25 °C.
- Keep the incubated plate closed; measure two perpendicular clear-zone diameters and calculate a mean, or calculate area with πr².
- Repeat each treatment on separate plates and compare mean clear-zone sizes.
Control
- bacterial strain and starting culture
- agar depth and plate size
- disc size and treatment volume
- incubation temperature and time
Graph or record
Use a bar chart for named treatments; use a line graph when concentration is a continuous variable.
Calculation
Compare mean zone diameter, or calculate zone area with area = πr² when the question asks for it.
Safety cue
- Use only the school-approved microorganism and follow trained supervision for flame sterilisation.
- Incubate at no more than 25 °C, tape without fully sealing to avoid anaerobic conditions, store plates upside down and never reopen them.
- Wear eye protection, disinfect spills as instructed and dispose of cultures through the school's sterilisation procedure.
Classic trap
Treating a large clear zone as proof that a treatment is safe or effective inside a person.
Revise it inside Cell Biology – AQA GCSE Biology Revision Guide →
Osmosis
A potato cylinder is a water-balance meter wearing a vegetable disguise.
- Question
- Measure how a range of salt or sugar concentrations changes the mass of equal plant-tissue pieces.
- Change or compare
- concentration of the salt or sugar solution
- Measure or observe
- percentage change in mass of the plant tissue
Open the exam playbook
Method in beats
- Prepare labelled tubes containing equal volumes of a range of salt or sugar concentrations, including distilled water.
- Cut plant-tissue cylinders to equal length and diameter, remove any skin, blot them consistently and record each initial mass.
- Place one cylinder in each solution for the same time at the same temperature.
- Remove each cylinder, blot it in the same way and record its final mass.
- Calculate percentage change in mass for every concentration.
- Repeat each concentration, calculate a mean and plot mean percentage change against concentration.
Control
- plant species and source tissue
- initial cylinder length and diameter
- solution volume
- immersion time and temperature
Graph or record
Plot solution concentration on the x-axis and percentage mass change on the y-axis; the zero crossing estimates no net water movement.
Calculation
Percentage change in mass = (final mass − initial mass) ÷ initial mass × 100.
Safety cue
- Use a tile and cut away from fingers when using a cork borer or scalpel; follow teacher supervision.
- Wear eye protection if the chosen solutions require it and wipe up spills promptly.
Classic trap
Comparing raw mass changes between unequal pieces instead of percentage change, or forgetting to blot before weighing.
Revise it inside Cell Biology – AQA GCSE Biology Revision Guide →
Food tests
Each reagent asks a different biological molecule to reveal itself with colour.
- Question
- Use visible results from standard reagents to test prepared food samples for reducing sugars, starch, protein and lipids.
- Change or compare
- food sample being compared while one food-group test is kept fixed
- Measure or observe
- the observed colour or layer produced by that fixed test
Open the exam playbook
Method in beats
- Prepare a food solution and divide it into separate, labelled samples.
- Add iodine solution to one sample; a blue-black result indicates starch.
- Add Benedict's solution to another sample and warm it in a water bath; a change away from blue towards green, yellow, orange or brick-red indicates reducing sugar.
- Add Biuret reagent to a fresh sample; a lilac or purple result indicates protein.
- Shake a fresh sample with ethanol, then add distilled water; a cloudy white emulsion indicates lipid.
- Compare each observation with a negative control and repeat uncertain results.
Control
- sample preparation and volume
- identity and volume of the reagent or reagents for the chosen test
- heating time and water-bath temperature for Benedict's test
- clean apparatus for each sample
Graph or record
A results table is normally clearer than a graph because the observations are categories and colours.
Calculation
This is qualitative evidence: record the starting appearance and the final positive or negative result rather than inventing a concentration.
Safety cue
- Wear eye protection and follow the reagent hazard guidance supplied by the school.
- Ethanol is highly flammable; keep it stoppered and well away from naked flames, hot equipment and other ignition sources.
- Biuret reagent contains corrosive sodium hydroxide and poisonous copper sulfate; avoid contact and rinse skin spills immediately.
- Heat Benedict's test indirectly in a water bath; use a holder for hot tubes and point them away from people.
Classic trap
Mixing up the reagent-result pairs or heating every test as though it were Benedict’s test.
Revise it inside Organisation – AQA GCSE Biology Revision Guide →
Amylase & pH
The reaction clock is hidden inside a row of iodine drops.
- Question
- Measure how pH affects the time taken for amylase to digest starch while keeping temperature constant.
- Change or compare
- pH of the reaction mixture
- Measure or observe
- time until starch is no longer detected, or rate calculated from that time
Open the exam playbook
Method in beats
- Place separate drops of iodine solution into the wells of a spotting tile.
- Bring measured starch, amylase and buffer solutions to the chosen water-bath temperature.
- Mix the starch and amylase with a buffer of known pH and start timing immediately.
- Every 30 seconds, transfer a drop of the reaction mixture to a fresh iodine drop.
- Record the first time at which the iodine remains orange-brown, showing that starch is no longer detected.
- Repeat at other pH values and repeat each condition before comparing mean times or calculated rates.
Control
- temperature
- amylase concentration and volume
- starch concentration and volume
- 30-second sampling interval
Graph or record
Plot pH on the x-axis and calculated rate on the y-axis to locate the optimum under the tested conditions.
Calculation
Rate is proportional to 1 ÷ time. If you use a scaled reciprocal such as 1000 ÷ time, define it consistently.
Safety cue
- Wear eye protection and avoid skin contact with iodine solution.
- Use a thermostatically controlled water bath at a safe temperature.
- Use clean transfer equipment and wipe up spills promptly.
Classic trap
Calling the shortest time the lowest rate, or changing the sampling interval between pH values.
Revise it inside Organisation – AQA GCSE Biology Revision Guide →
Photosynthesis
Pondweed turns invisible light energy into oxygen you can count—or, better, measure.
- Question
- Measure how changing light intensity affects the photosynthesis rate of an aquatic organism such as pondweed.
- Change or compare
- distance from the lamp or calculated light intensity
- Measure or observe
- mean oxygen-bubble count or oxygen volume released per unit time
Open the exam playbook
Method in beats
- Place a freshly cut piece of pondweed in sodium hydrogencarbonate solution with its cut end pointing upwards.
- Position a lamp at a measured distance from the pondweed and allow the apparatus to equilibrate.
- For a fixed time, count oxygen bubbles or collect and measure the volume of oxygen released.
- Repeat the measurement at the same distance and calculate a mean rate in bubbles/min or cm³/min.
- Move the lamp to several measured distances, allowing equilibration and repeating the timed measurement each time.
- Keep temperature, carbon dioxide supply, pondweed species and length, solution volume and measurement time constant.
- Plot mean photosynthesis rate against distance or, at Higher Tier, calculated relative light intensity 1/d².
Control
- temperature, using a heat shield or water bath
- carbon dioxide concentration and solution volume
- pondweed species, length and orientation
- measurement and equilibration times
Graph or record
Plot distance or relative light intensity on the x-axis and mean photosynthesis rate on the y-axis.
Calculation
Calculate oxygen produced per unit time. Higher Tier may use relative light intensity = 1 ÷ distance².
Safety cue
- Keep water away from electrical connections and dry hands before adjusting the lamp or leads.
- A lamp can become hot; use a heat shield, avoid touching the bulb and allow it to cool before moving it.
- Wear eye protection if instructed and avoid splashing the solution.
Classic trap
Assuming bubble count is perfectly proportional to oxygen volume, or letting the lamp change the temperature too.
Revise it inside Bioenergetics – AQA GCSE Biology Revision Guide →
Reaction time
Reaction time is not a personality trait. It is a measurement with noise, practice effects and controls.
- Question
- Use a ruler-drop test to investigate how the hand used affects one participant's reaction time.
- Change or compare
- hand used to catch the ruler
- Measure or observe
- catch distance in centimetres, used as an indicator of reaction time
Open the exam playbook
Method in beats
- Seat the participant with one forearm supported and their thumb and finger open beside the ruler's zero mark.
- Hold the ruler vertically so zero is level with the top of the participant's thumb, without giving a countdown.
- Release the ruler; the participant catches it as quickly as possible. Record the catch distance in centimetres.
- Repeat at least five times with the same hand, allowing short rests, then calculate a mean.
- Repeat the same procedure with the other hand and compare the mean catch distances.
- Repeat with more participants if making a group-level claim; present anonymised results and identify anomalies.
Control
- same ruler and release position
- same participant posture and catching technique
- same person releasing the ruler
- same number of repeats and rest interval
Graph or record
Use a bar chart for categories such as hand used; for a continuous factor, plot the factor against the reaction-time measure.
Calculation
Calculate a mean for each condition after identifying anomalies. A shorter ruler-drop distance indicates a faster response.
Safety cue
- Keep the floor and movement area clear and perform the test while seated.
- Obtain the participant's agreement, stop if they report discomfort and do not collect names or medical information.
- Use a light plastic or wooden ruler with smooth, undamaged edges.
Classic trap
Giving a countdown, changing the release position or generalising from one participant to everybody.
Revise it inside Homeostasis and Response – AQA GCSE Biology Revision Guide →
Seedling responses
A seedling cannot walk toward the light, so it solves the problem by changing how it grows.
- Question
- Investigate how one-sided light affects the direction of growth in newly germinated seedlings.
- Change or compare
- direction from which light reaches the seedlings
- Measure or observe
- change in shoot angle and shoot length over the fixed growth period
Open the exam playbook
Method in beats
- Choose similar newly germinated seedlings and measure each shoot's initial length and angle.
- Make a careful, labelled biological drawing of each starting seedling at a consistent scale.
- Place one group in a light-proof box with a side opening so light arrives from one direction.
- Place a control group in otherwise identical conditions with light arriving evenly from above.
- Keep water, temperature, species, seedling age, growing medium, time and light intensity as similar as possible.
- After a fixed period, measure the shoot length and angle of growth for every seedling.
- Make a second careful, labelled biological drawing at the same scale to show the growth response.
- Calculate group means and compare both growth amount and bending direction.
Control
- plant species and seedling age
- water volume and growing medium
- temperature and exposure time
- light intensity and distance from the lamp
Graph or record
Plot condition on the x-axis and mean angle or length change on the y-axis; keep drawings accurate, labelled and unshaded.
Calculation
Compare mean change in shoot angle and mean growth. Photographs taken from the same position can make angle measurements more reliable.
Safety cue
- Wash hands after handling seeds, seedlings and growing medium; do not eat laboratory plant material.
- Use a cool LED light and keep water away from electrical equipment.
- Handle scissors or craft tools only under teacher supervision when preparing boxes.
Classic trap
Changing light direction and light intensity together, then pretending only direction caused the result.
Revise it inside Homeostasis and Response – AQA GCSE Biology Revision Guide →
Field sampling
You cannot count every daisy in Britain. A good sample lets the small square speak for the field.
- Question
- Use quadrats to estimate a common species population and a transect to investigate how an environmental factor affects distribution.
- Change or compare
- position along the transect or the measured environmental factor associated with position
- Measure or observe
- abundance, frequency or percentage cover of the target species
Open the exam playbook
Method in beats
- Define the habitat boundary, identify the target species reliably and measure or obtain the total area.
- Generate random coordinate pairs, locate each position with tape measures and place a quadrat of known area.
- Count the target species using the same rule for organisms touching the boundary; repeat at many random positions.
- Calculate mean abundance or density and scale it to the habitat area to estimate population size.
- For distribution, lay a tape across an environmental gradient and place quadrats at regular distances to form a belt transect.
- At each distance, record target-species abundance and measure the relevant abiotic factor with suitable equipment.
- Repeat with parallel transects where practical, calculate means and plot abundance and the factor against distance.
- Look for a pattern, quote data and discuss other variables before suggesting a causal explanation.
Control
- quadrat dimensions and boundary-count rule
- distance between transect samples
- species-identification method
- time of day and weather where practical
Graph or record
Use position or the measured abiotic factor on the x-axis and abundance, frequency or percentage cover on the y-axis.
Calculation
Estimated population = mean count per quadrat × number of quadrat-sized areas in the habitat.
Safety cue
- Complete the school's fieldwork risk assessment; wear suitable footwear and clothing and avoid steep, unstable, roadside or deep-water sites.
- Do not touch unknown plants, fungi, animals, waste or sharp objects; cover cuts and wash hands after fieldwork.
- Keep the group together, follow site boundaries and weather guidance, and carry equipment so tapes and quadrats do not become trip hazards.
- Minimise disturbance: replace moved objects, avoid trampling outside the sample and release any organism promptly if observation is permitted.
Classic trap
Placing quadrats where the species is easiest to see, then calling the sample random.
Revise it inside Ecology – AQA GCSE Biology Revision Guide →
Milk decay
A fixed pH endpoint turns the speed of a milk-decay model into comparable data.
- Question
- Investigate how temperature affects the rate of decay of fresh milk by timing a fixed pH change.
- Change or compare
- temperature of the milk and lipase mixture in the water bath
- Measure or observe
- time to a fixed pH endpoint and calculated relative rate, 1 / time
Open the exam playbook
Method in beats
- Label tubes for several temperatures; add equal volumes of fresh milk and sodium carbonate for the same alkaline start, then the same amount of Cresol red, to each.
- Prepare equal portions of the same lipase solution, which models decay by breaking milk fat into fatty acids that lower pH.
- Place each milk mixture and lipase portion in its water bath until both reach the target temperature; verify with a thermometer.
- Add the lipase to the milk, mix in the same way and start the timer immediately.
- Stop timing at one defined indicator-colour or pH endpoint and record the time in seconds.
- Repeat at each temperature, calculate a mean endpoint time and calculate relative rate = 1 / mean time.
- Plot mean relative rate against temperature and describe the pattern within the measured range.
Control
- milk volume and starting batch
- lipase volume and concentration
- sodium carbonate volume and concentration
- indicator identity and volume
Graph or record
Plot temperature on the x-axis and mean relative rate on the y-axis; do not extrapolate beyond the measured range.
Calculation
Relative rate = 1 ÷ time to the fixed pH endpoint. Calculate a mean for each temperature before comparing rates.
Safety cue
- Wear eye protection. Lipase, sodium carbonate and indicator can irritate skin or eyes; use prepared solutions, avoid aerosols and rinse splashes as instructed.
- Use thermostatically controlled water baths, heatproof mats and test-tube racks; take care with hot water and glassware.
- Use fresh pasteurised milk; check school allergy information, avoid skin contact, never taste materials, clean spills and follow the disposal procedure.
- Carry out the practical under trained school supervision and follow the reagent-specific risk assessment.
Classic trap
Presenting the accelerated lipase activity as literal microbial milk decay, or comparing different colour or pH endpoints.
Revise it inside Ecology – AQA GCSE Biology Revision Guide →
Make the method move
Variables planner
Pick a practical. The planner turns the method into the five things an exam answer must keep straight.
Use a light microscope to observe plant and animal cells
- 1Question
Prepare, observe, draw and label plant and animal cells using a light microscope, including a magnification scale.
- 2Change or compare
type of prepared cell specimen or magnification being compared
- 3Measure or observe
structures resolved and measurements made in the microscope image
- 4Plot
Usually no graph: the evidence is a clear biological drawing, labels and a meaningful magnification scale.
- 5Challenge
Drawing artistic shading or labelling structures that the image does not actually resolve.
Decode the command
What the question is really asking
A six-mark method and an evaluation question may use the same experiment, but they are asking your brain to perform different jobs.
Make the comparison fair
Name what changes or is compared, what is observed or measured, the controls that matter, suitable repeats where relevant and a safe, ordered method.
Write actions, not intentions.Turn readings into evidence
Calculate what the question needs, choose the right table, drawing, scale or graph, then describe the evidence precisely.
Pattern first; explanation second.Find the weak link
Identify a specific limitation, explain how it changes the evidence, then propose a practical improvement that addresses it.
Problem → consequence → fix.- Question
- Comparison
- Observation
- Record
- Verdict
Ten quick confidence checks
Revision checklist
Mark a practical confident only when you can name its variables, evidence and biggest trap without opening the playbook.
Clear up the awkward bits
Frequently asked questions
How many AQA GCSE Biology required practicals are there?
There are ten in the Separate Biology qualification. Seven are shared with Combined Science: Trilogy; practicals 2, 8 and 10 are Separate Biology only.
Does “Biology only” mean Higher Tier only?
No. Separate Biology practicals can be assessed at Foundation and Higher Tier. The course route and the tier are different things.
Do I need to memorise one exact method?
Learn the purpose, variables, measurements, safety and logic of the method. Exam questions can place the same skills in an unfamiliar context, so understanding beats reciting a script.
Can I use this page as a laboratory method sheet?
No. This is a revision guide. Practical work must be supervised by a trained teacher and follow the school’s current risk assessment, reagent instructions and equipment procedures.