AQA GCSE Biology (8461)

AQA GCSE Biology Required Practicals

AQA GCSE Biology lists ten required practical activities. Seven are shared with GCSE Combined Science, and practicals 2, 8 and 10 are on the separate Biology specification only. Written papers can ask about the methods, the variables, the data and how you would improve the investigation, so revise the thinking behind each practical rather than the instructions alone.

Required practical 1

Microscopy

Using a light microscope to observe, draw and label plant and animal cells, including a magnification scale on the drawing.

Aim

Observe cell structures that are too small to see unaided and record them as accurate, scaled biological drawings.

Method

  1. Prepare a slide: place the specimen on the slide, add a drop of stain such as iodine, then lower a coverslip at an angle to avoid air bubbles.
  2. Clip the slide onto the stage and select the lowest power objective lens.
  3. Use the coarse focus to bring the stage and objective close, then focus by moving them apart while looking through the eyepiece.
  4. Sharpen the image with the fine focus, then switch to a higher power objective and refocus with the fine focus only.
  5. Draw what you actually see with a sharp pencil, using clear unbroken lines, no shading, and label lines that do not cross.
  6. Record the total magnification and add a magnification scale to the drawing.

Variables

Dependent
The structures observed and their measured or estimated size
Control
  • Same specimen preparation and stain
  • Same lighting
  • Refocus with the fine focus only at high power

Equipment

Light microscope, Slides and coverslips, Iodine or methylene blue stain, Mounted needle, Pencil and ruler.

Results and observations

Plant cells show a cell wall, large permanent vacuole and often chloroplasts; animal cells show a membrane, cytoplasm and nucleus but no wall or chloroplasts.

Calculations

  • Total magnification = eyepiece magnification × objective magnification
  • Magnification = size of image ÷ size of real object (rearrange to find real size)
  • Convert carefully: 1 mm = 1000 µm

Graphs and data

No graph is needed, but you must be able to use a scale bar and convert between millimetres and micrometres.

Evaluation

  • Air bubbles under the coverslip can be mistaken for cells, so lower the coverslip slowly at an angle.
  • Too much stain darkens the field and hides detail.
  • Estimating size from a drawing is less reliable than using a stage micrometer or an eyepiece graticule.

Common mistakes

  • Focusing downwards at high power and cracking the slide.
  • Drawing what a textbook shows rather than what is on the slide.
  • Forgetting units or the magnification scale on the drawing.

Quick self-test

An image is 50 mm across and the magnification is ×100. What is the real width in micrometres?

50 mm ÷ 100 = 0.5 mm, which is 500 µm.

Why is a stain used when preparing a slide?

It increases contrast so that structures such as the nucleus become visible against the cytoplasm.

Give two structures visible in a plant cell but not in an animal cell.

Cell wall and chloroplasts (a large permanent vacuole is also acceptable).

Linked topic: Cell Structure revision

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Required practical 2 · separate biology only

Microbiology: antiseptics and antibiotics

Investigating the effect of antiseptics or antibiotics on bacterial growth using agar plates and measuring zones of inhibition.

Aim

Compare how effectively different antimicrobial substances (or different concentrations) inhibit bacterial growth.

Method

  1. Work using aseptic technique: sterilise equipment, flame the neck of the culture bottle and lift the lid of the Petri dish at an angle only.
  2. Spread a uniform lawn of bacteria over sterile nutrient agar with a sterile spreader.
  3. Soak filter paper discs in each antiseptic or antibiotic, plus one in sterile water as a control, and blot off the excess.
  4. Place the discs evenly spaced on the agar and secure the lid with tape (do not seal it completely).
  5. Incubate inverted at no more than 25 °C in a school laboratory for around 48 hours.
  6. Measure the diameter of each clear zone of inhibition and calculate its area.

Variables

Independent
The antiseptic or antibiotic used, or its concentration
Dependent
The size of the zone of inhibition (diameter, then area)
Control
  • Same bacterial species and lawn density
  • Same incubation temperature and time
  • Same disc size and volume of solution
  • Same agar type and depth

Equipment

Sterile agar plates, Bacterial culture and sterile spreader, Sterile filter paper discs, Forceps, Ruler, Incubator.

Results and observations

A clear zone around a disc shows bacteria have been killed or prevented from growing; a larger zone indicates a more effective substance.

Calculations

  • Area of a zone of inhibition = πr², where r is half the measured diameter
  • Calculate a mean area from repeats for each substance

Graphs and data

Plot mean zone area as a bar chart for different substances, or as a line graph against concentration.

Evaluation

  • The sterile water control shows any zone is caused by the substance and not the disc itself.
  • Measure the diameter in two directions and take a mean because zones are rarely perfect circles.
  • Repeats and a consistent lawn density improve reliability; contamination is the main source of anomalies.
  • Incubating at 25 °C reduces the risk of growing pathogens that thrive at human body temperature.

Common mistakes

  • Comparing diameters when the question asks for area.
  • Leaving the Petri dish lid fully open, allowing airborne contamination.
  • Forgetting to state a control disc soaked in sterile water.

Quick self-test

Why is a disc soaked in sterile water used?

It is a control: it shows that any clear zone is caused by the antiseptic or antibiotic and not by the paper disc itself.

A zone of inhibition has a diameter of 18 mm. Calculate its area.

r = 9 mm, so area = pi x 9^2 = 254 mm^2 (3 s.f.).

Give one reason plates are incubated at 25 degrees C in school.

Lower temperatures reduce the risk of growing microorganisms that are pathogenic to humans.

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Required practical 3

Osmosis

Investigating the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue.

Aim

Find how the concentration of a surrounding solution affects net water movement into or out of plant cells.

Method

  1. Cut cylinders of potato with a cork borer and trim them to the same length.
  2. Blot each cylinder dry and record its initial mass.
  3. Place one cylinder in each of a range of sugar concentrations (for example 0.0 to 1.0 mol/dm³), fully submerged.
  4. Leave for a set time, for example 30 minutes or overnight.
  5. Remove, blot gently to remove surface liquid and record the final mass.
  6. Repeat at each concentration and calculate percentage change in mass.

Variables

Independent
Concentration of the sugar or salt solution
Dependent
Percentage change in mass of the plant tissue
Control
  • Same tissue type, length and surface area
  • Same volume of solution
  • Same time in solution
  • Same temperature
  • Same blotting method

Equipment

Potato and cork borer, Scalpel and tile, Balance, Boiling tubes or beakers, Sugar solutions of known concentration, Paper towels.

Results and observations

Cylinders gain mass in dilute solutions (water enters by osmosis), lose mass in concentrated solutions, and show no net change where the solution concentration matches the cell contents.

Calculations

  • Percentage change in mass = (final mass − initial mass) ÷ initial mass × 100
  • Read the concentration where the line crosses 0% change to estimate the internal concentration of the tissue

Graphs and data

Plot percentage change in mass (y) against concentration (x) and draw a line of best fit; the x-intercept is the isotonic point.

Evaluation

  • Percentage change is used rather than raw change so cylinders of slightly different starting mass can be compared fairly.
  • Inconsistent blotting is the biggest source of error, as surface water adds mass.
  • Repeats at each concentration allow a mean and make anomalies visible.

Common mistakes

  • Reporting change in mass instead of percentage change.
  • Saying sugar molecules move into the cell rather than water moving out.
  • Leaving cylinders in solution for different lengths of time.

Quick self-test

Why is percentage change in mass used rather than change in mass?

The cylinders do not all start with exactly the same mass, so percentage change allows a fair comparison between them.

A cylinder shows no change in mass. What does this tell you?

The concentration of the solution is the same as the concentration inside the cells, so there is no net movement of water.

Suggest one improvement to reduce error in this practical.

Blot every cylinder for the same time in the same way, since surface water added or left behind changes the recorded mass.

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Required practical 4

Food tests

Using qualitative reagents to test for carbohydrates, lipids and proteins: Benedict's test for sugars, iodine for starch and Biuret reagent for protein.

Aim

Identify the biological molecules present in a food sample using colour-change reagents.

Method

  1. Grind the food sample and mix with distilled water to make a solution, then filter it.
  2. Starch: add a few drops of iodine solution to a sample.
  3. Sugars: add Benedict's solution to a sample and heat in a water bath at about 75 °C for a few minutes.
  4. Protein: add Biuret reagent to a sample and mix.
  5. Lipids: mix the sample with ethanol, then pour into water (the emulsion test).
  6. Record the colour of each test alongside a negative control of distilled water.

Variables

Independent
The food sample tested
Dependent
The colour observed in each test
Control
  • Same volume of sample and reagent
  • Same water bath temperature and heating time
  • Distilled water negative control

Equipment

Pestle and mortar, Test tubes and rack, Water bath, Iodine solution, Benedict's solution, Biuret reagent, Ethanol.

Results and observations

Starch: orange-brown to blue-black. Reducing sugars: blue to green, yellow, orange or brick red depending on amount. Protein: blue to purple. Lipids: clear to a milky white emulsion.

Calculations

  • No calculation is required, though Benedict's colour can be used to rank samples semi-quantitatively.

Graphs and data

Record results in a table of food sample against test result rather than a graph.

Evaluation

  • The tests are qualitative, so they show presence rather than exact amount.
  • Benedict's does not detect non-reducing sugars such as sucrose without further treatment.
  • A negative control confirms the colour change comes from the food, not the reagent.

Common mistakes

  • Describing the Benedict's result as simply 'red' without stating the starting blue colour.
  • Not heating the Benedict's test, which gives a false negative.
  • Confusing the iodine and Biuret colour changes.

Quick self-test

A student adds Benedict's solution and sees no change. Suggest two possible reasons.

There is no reducing sugar present, or the mixture was not heated in a hot water bath so the reaction did not occur.

State the colour change for a positive protein test.

Biuret reagent changes from blue to purple.

Why are these tests described as qualitative?

They show whether a substance is present but do not measure how much of it there is.

Linked topic: Enzymes revision

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Required practical 5

Effect of pH on amylase

Investigating the effect of pH on the rate of reaction of amylase using continuous sampling, testing for starch with iodine every 30 seconds.

Aim

Find how pH affects how quickly amylase breaks down starch.

Method

  1. Place drops of iodine solution in the wells of a spotting tile.
  2. Mix starch solution and a buffer of known pH in a test tube and place in a water bath at a fixed temperature.
  3. Add amylase, mix and start the stopwatch.
  4. Every 30 seconds transfer a drop of the mixture to a fresh well of iodine.
  5. Record the time when the iodine first stays orange-brown, showing all the starch has been digested.
  6. Repeat with buffers at different pH values.

Variables

Independent
pH of the buffer solution
Dependent
Time taken for the starch to be fully digested
Control
  • Temperature (water bath)
  • Concentration and volume of amylase and starch
  • Sampling interval of 30 seconds
  • Same iodine concentration

Equipment

Amylase and starch solutions, pH buffers, Spotting tile and iodine, Water bath, Stopwatch, Pipettes.

Results and observations

Digestion is fastest at the optimum pH (shortest time). Times get longer either side, and at extreme pH the starch may never be fully digested because the enzyme is denatured.

Calculations

  • Rate of reaction = 1 ÷ time taken (units s⁻¹)
  • Calculate a mean time from repeats before finding the rate

Graphs and data

Plot rate (1/time) against pH; the peak of the curve identifies the optimum pH.

Evaluation

  • Sampling every 30 seconds means the true end point lies somewhere in that interval, which limits resolution.
  • Judging the colour change is subjective, so a colorimeter would be more objective.
  • A water bath keeps temperature constant, otherwise temperature would be a confounding variable.

Common mistakes

  • Plotting time instead of rate and then describing the curve backwards.
  • Saying the enzyme is 'killed' rather than denatured.
  • Forgetting that no colour change at extreme pH means no reaction, not a missing result.

Quick self-test

Why must the temperature be kept constant in this investigation?

Temperature also affects enzyme activity, so if it varied you could not tell whether the change in rate was caused by pH.

Starch is digested in 60 s. Calculate the rate.

Rate = 1 / 60 = 0.017 s^-1.

At pH 2 the iodine still turns blue-black after 10 minutes. Explain why.

The enzyme has been denatured at this pH, so its active site no longer fits the starch and little or no digestion occurs.

Linked topic: Enzymes revision

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Required practical 6

Light intensity and photosynthesis

Investigating the effect of light intensity on the rate of photosynthesis using an aquatic organism such as pondweed.

Aim

Show how the rate of photosynthesis changes as light intensity changes.

Method

  1. Place a piece of pondweed in a boiling tube of sodium hydrogencarbonate solution to supply carbon dioxide.
  2. Put the tube in a beaker of water acting as a heat shield to keep temperature constant.
  3. Place a lamp a set distance from the tube and leave for a few minutes to acclimatise.
  4. Count the bubbles of oxygen released in one minute, or collect and measure the gas volume.
  5. Repeat at a range of distances from the lamp.
  6. Repeat each distance and calculate a mean.

Variables

Independent
Light intensity, varied by changing the distance of the lamp
Dependent
Rate of oxygen production (bubbles per minute or volume of gas per minute)
Control
  • Temperature
  • Carbon dioxide concentration
  • Same piece of pondweed
  • Same time interval
  • Background light kept constant

Equipment

Pondweed, Boiling tube and beaker, Sodium hydrogencarbonate solution, Lamp, Ruler, Stopwatch, Gas syringe or capillary tube.

Results and observations

The rate rises as light intensity increases, then levels off when another factor such as carbon dioxide concentration or temperature becomes limiting.

Calculations

  • Light intensity is proportional to 1 ÷ d², where d is the distance from the lamp (the inverse square law)
  • Rate = volume of gas or number of bubbles ÷ time

Graphs and data

Plot rate against 1/d²; expect a positive correlation that plateaus at high intensity.

Evaluation

  • Counting bubbles is imprecise because bubbles vary in size, so collecting gas volume is more accurate.
  • A heat shield stops the lamp warming the water, which would change temperature as well as light.
  • Allowing time to acclimatise at each distance gives a steadier rate.

Common mistakes

  • Using distance directly as light intensity instead of 1/d².
  • Saying photosynthesis 'stops' at the plateau rather than being limited by another factor.
  • Not controlling the light in the room.

Quick self-test

Why is sodium hydrogencarbonate solution added?

It supplies carbon dioxide so that carbon dioxide concentration does not become the limiting factor.

The lamp is 25 cm away. Calculate the relative light intensity using the inverse square law.

1 / 25^2 = 0.0016 arbitrary units.

Explain why the rate levels off at high light intensity.

Another factor, such as carbon dioxide concentration or temperature, has become the limiting factor.

Linked topic: Photosynthesis revision

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Required practical 7

Reaction time

Planning and carrying out an investigation into the effect of a factor on human reaction time.

Aim

Measure how a chosen factor, such as caffeine, background noise or the hand used, affects reaction time.

Method

  1. The subject sits with their forearm over the edge of a table and thumb and forefinger open.
  2. A partner holds a ruler vertically with the zero mark between the subject's fingers.
  3. Drop the ruler without warning; the subject catches it as quickly as possible.
  4. Record the distance fallen in centimetres at the top of the thumb.
  5. Repeat several times and discard obvious anomalies, then calculate a mean.
  6. Change the chosen factor and repeat the whole procedure.

Variables

Independent
The chosen factor, for example caffeine intake, dominant versus non-dominant hand or background noise
Dependent
Distance the ruler falls, converted to reaction time
Control
  • Same subject
  • Same hand and starting finger position
  • Same ruler and drop height
  • No countdown or warning
  • Same time of day where possible

Equipment

30 cm or metre ruler, Chair and table, Optional: computer reaction-timer program.

Results and observations

A shorter drop distance means a faster reaction. Results usually improve slightly with practice, so early trials can be higher than later ones.

Calculations

  • Convert distance to time using t = √(2s ÷ g), with s in metres and g = 9.8 m/s²
  • Calculate a mean distance or time from the repeats

Graphs and data

Use a bar chart to compare conditions, or a scatter graph if the factor is continuous.

Evaluation

  • Anticipation is a major source of error, so avoid patterns or countdowns.
  • Human variation means comparing conditions on the same person is more valid than comparing people.
  • A computer-based test removes the partner's inconsistent release and measures time directly.

Common mistakes

  • Treating distance as if it were time without converting.
  • Averaging in obvious anomalies caused by a missed catch.
  • Changing more than one factor between conditions.

Quick self-test

Why should the ruler be dropped without warning?

A warning lets the subject anticipate the drop, so the measurement no longer reflects their true reaction time.

Give one reason for testing the same person under both conditions.

It controls for natural variation between people, making the comparison of the factor more valid.

The ruler falls 0.20 m. Calculate the reaction time using t = sqrt(2s/g).

t = sqrt(2 x 0.20 / 9.8) = 0.20 s (2 s.f.).

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Required practical 8 · separate biology only

Plant responses

Investigating the effect of light or gravity on the growth of newly germinated seedlings, recording results as measurements and labelled biological drawings.

Aim

Show how seedlings respond to a directional stimulus through phototropism or gravitropism.

Method

  1. Germinate seedlings on damp cotton wool or filter paper in identical dishes.
  2. For light: place groups in full light, unidirectional light through a slit, and darkness.
  3. For gravity: keep some dishes upright and turn others through 90 degrees, using a klinostat as a control if available.
  4. Leave for several days, keeping water supply the same.
  5. Measure the length of shoots and roots and record the direction of growth.
  6. Make accurate labelled drawings showing the direction of bending.

Variables

Independent
Direction or presence of light, or the orientation relative to gravity
Dependent
Length of shoot or root and the direction of growth
Control
  • Same species and number of seedlings
  • Same water supply
  • Same temperature
  • Same growth time

Equipment

Cress or similar seedlings, Petri dishes, Cotton wool or filter paper, Light source and card with a slit, Ruler, Klinostat (optional).

Results and observations

Shoots grow towards unidirectional light (positive phototropism) and away from gravity; roots grow towards gravity. Seedlings in darkness are typically longer, thin and pale.

Calculations

  • Calculate mean shoot or root length for each condition
  • Measure the angle of bending if comparing responses

Graphs and data

Bar chart of mean length by condition, supported by labelled drawings of the direction of growth.

Evaluation

  • Seedlings vary naturally, so use several per condition and take a mean.
  • A klinostat controls for the effect of rotation itself when testing gravity.
  • Measuring a curved shoot with a straight ruler underestimates its true length.

Common mistakes

  • Saying plants 'want' to grow towards light rather than describing unequal auxin distribution.
  • Using only one seedling per condition.
  • Not keeping the seedlings equally watered.

Quick self-test

Explain why several seedlings are used in each condition.

Individual seedlings vary, so a mean from several reduces the effect of that natural variation.

Predict what happens to shoots given light from one side only.

They grow towards the light because auxin accumulates on the shaded side and causes greater elongation there.

Why are seedlings grown in the dark taller and paler?

They elongate rapidly searching for light and cannot make chlorophyll without it.

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Required practical 9

Field investigations

Measuring the population size of a common species in a habitat and using sampling techniques to investigate the effect of a factor on its distribution.

Aim

Estimate population size and show how an abiotic factor affects where a species is found.

Method

  1. For population size, place quadrats at random using coordinates from a random number generator over a gridded area.
  2. Count the number of individuals, or estimate percentage cover, in each quadrat.
  3. Repeat for a suitable number of quadrats and calculate a mean per quadrat.
  4. For distribution, lay a transect line from one habitat condition to another, for example from open ground into shade.
  5. Place quadrats at regular intervals along the transect and record abundance plus the abiotic factor, such as light intensity or soil moisture.
  6. Record all data in a results table as you go.

Variables

Independent
Distance along the transect, or the abiotic factor being investigated
Dependent
Number of individuals or percentage cover of the species
Control
  • Same quadrat size
  • Same sampling method and counting rules
  • Same time of day and weather conditions

Equipment

Quadrats, Tape measure or transect line, Random number generator, Light meter or soil moisture meter, Identification key.

Results and observations

Abundance usually changes systematically along the transect as the abiotic factor changes; random quadrats give a mean used to estimate the total population.

Calculations

  • Mean number per quadrat = total counted ÷ number of quadrats
  • Estimated population = mean per quadrat × (total area ÷ area of one quadrat)

Graphs and data

Plot abundance against distance along the transect as a line graph, or use a kite diagram to show distribution.

Evaluation

  • Sampling must be random for population estimates, otherwise the result is biased.
  • More quadrats reduce the effect of chance and make the estimate more reliable.
  • Percentage cover is subjective; counting individuals is more precise where the species is countable.

Common mistakes

  • Placing quadrats where the species looks abundant instead of randomly.
  • Forgetting to scale the mean up by total area when estimating the population.
  • Using a transect for a population estimate, which is intended for distribution.

Quick self-test

Why must quadrat positions be chosen randomly?

Choosing where to place quadrats introduces bias, which would make the population estimate unrepresentative.

Mean count is 6 per 0.25 m^2 quadrat over a 200 m^2 field. Estimate the population.

200 / 0.25 = 800 quadrat areas, so 800 x 6 = 4800 individuals.

When is a transect used rather than random quadrats?

When investigating how distribution changes across a gradient, such as from shade into open ground.

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Required practical 10 · separate biology only

Rate of decay

Investigating the effect of temperature on the rate of decay of fresh milk by measuring pH change.

Aim

Show how temperature affects the activity of decay microorganisms, measured through the acid they produce.

Method

  1. Measure a fixed volume of fresh milk into a boiling tube and add a fixed volume of lipase and sodium carbonate solution with cresol red indicator.
  2. Place the tube in a water bath at a set temperature and allow it to reach that temperature.
  3. Start the stopwatch and record the time taken for the indicator to change from purple to yellow, showing the pH has fallen.
  4. Alternatively, record pH with a pH meter at fixed time intervals.
  5. Repeat at a range of temperatures.
  6. Repeat each temperature and take a mean.

Variables

Independent
Temperature
Dependent
Time taken for the pH to fall to the end point, or pH after a fixed time
Control
  • Volume and concentration of milk, lipase and indicator
  • Same starting pH
  • Same end-point colour judgement
  • Same tube and mixing

Equipment

Fresh milk, Lipase solution, Sodium carbonate solution, Cresol red indicator or pH meter, Water baths, Stopwatch, Thermometer.

Results and observations

The pH falls as fatty acids are produced. The change is fastest at the optimum temperature and slower at low temperatures; at high temperatures enzymes denature and the reaction slows or stops.

Calculations

  • Rate = 1 ÷ time to reach the end point
  • Mean time from repeats before calculating rate

Graphs and data

Plot rate against temperature; expect a peak at the optimum temperature.

Evaluation

  • Judging a colour end point by eye is subjective; a pH meter or colorimeter is more objective.
  • Water baths must be checked with a thermometer because they drift.
  • The tube needs time to reach the water bath temperature before timing starts.

Common mistakes

  • Saying the pH rises rather than falls as acid is produced.
  • Not allowing the mixture to reach the set temperature before starting.
  • Reporting time as though it were the rate.

Quick self-test

Explain why the pH of the milk falls.

Microorganisms and lipase break down fats to produce fatty acids, which lower the pH.

Why is a water bath used rather than heating directly?

It holds the mixture at a steady, known temperature, which is the variable being investigated.

Suggest why the rate falls at very high temperatures.

The enzymes are denatured, so their active sites no longer fit their substrates.

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Practical names follow the required practical activities listed in the official AQA GCSE Biology 8461 specification. Always check the current specification for the authoritative list.

How to answer GCSE required practical questions

Practical questions rarely ask you to recite a method. They usually give data, a diagram or an unfamiliar setup and test whether you can think like an experimenter. The exact skills depend on the practical and on the specification you are sitting, so use this as a checklist rather than a prediction.

  • Identifying variablesPick out what was changed, what was measured and what had to stay the same.
  • Choosing control variablesName the specific variables that would otherwise affect the dependent variable.
  • Describing a valid methodWrite steps in order, with quantities and a clear measurement, so someone else could repeat it.
  • Selecting measurementsChoose apparatus with a sensible resolution and range for what you are measuring.
  • Recording resultsUse a table with headings, units and a consistent number of decimal places.
  • Calculating valuesMeans, percentage change, rate, gradient, density and other calculations set by the practical.
  • Plotting and reading graphsSensible scales, labelled axes with units, plotted points and a line of best fit.
  • Identifying anomaliesSpot results that do not fit the pattern, exclude them from means and suggest a cause.
  • Evaluating reliabilityExplain how repeats, means and controlled variables strengthen a conclusion.
  • Sources of errorSeparate random error from systematic error and say which affects your data.
  • Suggesting improvementsChange one specific thing and say what it would improve, rather than 'be more careful'.
  • Drawing conclusionsState the relationship the data supports and refer back to the values you collected.
  • Applying to new contextsUse the same reasoning on an unfamiliar experiment you have never carried out.

GCSE Required Practical Exam Questions

These are original practice questions written for this page, not past-paper questions. They cover the skills practical questions tend to test: variables, calculations, anomalies, graphs and improvements.

BiologyA student investigates the effect of sugar concentration on the mass of potato cylinders. Identify the independent variable and one control variable.

Independent variable: the concentration of the sugar solution. A control variable could be the length or surface area of the potato cylinders, the volume of solution, the temperature or the time left in solution.

BiologyIn an osmosis investigation, a cylinder starts at 4.0 g and ends at 3.4 g. Calculate the percentage change in mass.

(3.4 − 4.0) ÷ 4.0 × 100 = −15%. The negative sign shows the cylinder lost mass, so water moved out of the cells.

BiologyExplain why a student repeats each light intensity three times in the photosynthesis practical.

Repeats allow a mean to be calculated, which reduces the effect of random error, and they make anomalous results easier to spot so they can be excluded.

BiologyA results table shows the cross disappeared in 42 s, 44 s and 78 s at the same concentration. Explain what the student should do.

Treat 78 s as an anomaly, exclude it from the mean and, if possible, repeat that run. The anomaly may be caused by a misjudged end point, a wrong volume or a different observer.

GCSE Required Practical Flashcards & Quizzes

Practical revision suits active recall because most of it is small, precise detail: which reagent, which variable, which unit. Reading a method again feels productive but rarely shows you what you cannot remember. Testing yourself does.

  • Equipment and apparatus
  • Method steps in order
  • Independent, dependent and control variables
  • Expected observations
  • Calculations and units
  • Graph shapes and gradients
  • Evaluation and sources of error
  • Conclusions from data

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AQA GCSE Required Practicals FAQs

What are GCSE required practicals?

They are the practical activities AQA states every student must carry out during the course. There is no separate practical exam at GCSE: instead, the written papers include questions that draw on the knowledge, skills and understanding you gained from doing them.

How many AQA GCSE Biology required practicals are there?

The AQA GCSE Biology (8461) specification lists ten required practical activities. Seven of them are shared with GCSE Combined Science, while practicals 2, 8 and 10 are on the separate Biology specification only.

How many AQA GCSE Chemistry required practicals are there?

The AQA GCSE Chemistry (8462) specification lists eight required practical activities. Titration, identifying ions and water purification appear on the separate Chemistry specification rather than Combined Science.

How many AQA GCSE Physics required practicals are there?

The AQA GCSE Physics (8463) specification lists ten required practical activities, of which thermal insulation and the light practical are on the separate Physics specification only.

Do required practicals appear in GCSE exams?

AQA states that written papers include questions requiring knowledge gained from carrying out the specified practicals. The exact questions vary from paper to paper, so no one can tell you which practical will come up or how many marks it will carry.

How should I revise required practicals?

For each practical, be able to state the aim, outline the method in order, identify the independent, dependent and control variables, describe what the results show, do any calculation involved and suggest one improvement. Then self-test rather than re-reading, which is where flashcards and exam-style questions help.

Are required practicals the same for every exam board?

No. Every board has to cover the same underlying apparatus and techniques requirements, but the named practical activities and their wording differ between AQA, Edexcel and OCR. Use the list that matches the specification you are entered for.

Where can I check the official list?

AQA publishes the required practical activities in the practical assessment section of each specification, and provides a required practical handbook with suggested methods. Always treat AQA as the authoritative source for the current list.

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