SPM Biology Paper 3 experiments

Designing a Scientific Investigation

How to turn a problem statement into a testable aim, identify variables, and design a fair, repeatable experiment for SPM Biology Paper 3.

Prepare Slides of Animal and Plant Cells

How to prepare temporary mounts of onion epidermis and human cheek cells, and compare plant and animal cell structure under a microscope.

Investigating Osmosis Using Visking Tubing

How to demonstrate osmosis across visking tubing using a simple osmometer, and how the level of solution in the tube changes over time.

Effects of Solution Concentration on Cells

How immersing plant epidermis and, by comparison, animal cells in solutions of different concentration affects turgidity, plasmolysis, and haemolysis.

Determine the Concentration of Cell Sap of a Plant Tissue

How to use the change-in-mass method with potato cylinders to determine the concentration of cell sap of a plant tissue.

Effects of Temperature and pH on Amylase and Pepsin Activity

How temperature affects amylase's digestion of starch and how pH affects pepsin's digestion of protein, with method, results and common mistakes.

Investigating Aerobic Respiration in Germinating Seeds

How to show that germinating seeds respire aerobically, releasing carbon dioxide and heat while consuming oxygen, with method and results.

Investigating Fermentation in Yeast

How to investigate anaerobic respiration (fermentation) in yeast and how temperature affects the rate of carbon dioxide production.

Using a Light Microscope

The parts of a compound light microscope and the correct steps for focusing a specimen from low power to high power.

Preparing a Temporary Slide (Wet Mount)

The wet-mount method for preparing a temporary slide of plant or animal cells, including staining and avoiding air bubbles.

Calculating Magnification

How to use the magnification formula (image size divided by actual size) to solve microscope and diagram questions, with unit conversion and a worked example.

Identifying Variables

How to identify the manipulated, responding, and controlled variables in a biology experiment or exam question.

Writing a Hypothesis

How to write a clear, testable hypothesis that links the manipulated variable and the responding variable in a biology investigation.

Tabulating Data

The rules for drawing a results table in a biology experiment, including column order, headings with units, and consistent decimal places.

Drawing Graphs

How to choose the correct graph type, label axes with units, plot points, draw a line of best fit, and read values from a graph in biology.

Planning an Experiment

The key components of a well-designed biology experiment, aim, variables, apparatus, method, control, and repeats, for Paper 3 planning questions.

Investigating the Digestion of Starch, Protein and Lipid by Enzymes

How food tests are used to show that amylase, pepsin (or trypsin) and lipase digest starch, protein and lipid in food samples.

Energy Values in Food Samples

How to compare the energy value of different food samples by burning them and measuring the temperature rise they cause in a fixed volume of water.

Vitamin C Content in Fruit Juices and Vegetables

How to compare the vitamin C content of different fruit juices or vegetable extracts using the DCPIP decolourisation method.

Effect of Water Intake on Urine Volume

A supervised class activity investigating how the volume of water a person drinks affects the volume and concentration of urine produced.

Food Test for Starch (Iodine Test)

How to carry out the iodine test for starch in food, including method, positive result, and common mistakes.

Food Test for Reducing Sugar (Benedict's Test)

How to carry out the Benedict's test for reducing sugar in food, including method, positive result, and common mistakes.

Food Test for Protein (Biuret Test)

How to carry out the Biuret test for protein in food, including method, positive result, and common mistakes.

Food Test for Lipid (Emulsion Test)

How to carry out the emulsion test for lipid in food, including method, positive result, and common mistakes.

Food Test for Vitamin C (DCPIP Test)

How to carry out the DCPIP test for vitamin C in food, including method, positive result, and common mistakes.

Zones of Cell Division, Elongation and Differentiation in a Radicle

How to identify the zones of cell division, cell elongation and cell differentiation along a growing root tip using the ink-marking method.

Studying the Growth Curve of a Plant

How to measure a seedling's height over time to plot a growth curve, showing why plant growth follows an S-shaped (sigmoid) pattern.

Comparing Stomatal Distribution on Monocot and Eudicot Leaves

How to compare the number of stomata on the upper and lower epidermis of a monocot and a eudicot leaf using nail varnish impressions.

Investigating the Effect of Environmental Factors on the Rate of Transpiration

How to use a potometer to measure the rate of water uptake in a leafy shoot and investigate the effect of wind, light, or humidity on transpiration.

Investigating the Effect of Light Intensity on the Rate of Photosynthesis

How to use Hydrilla and a lamp at different distances to investigate the effect of light intensity on the rate of photosynthesis by counting oxygen bubbles.

Effectiveness of a Phytoremediation Plant in Controlling Water Pollution

A Paper 3 experiment testing whether a phytoremediation plant such as water hyacinth reduces pollutant levels in water faster than an untreated control.

Effect of the Phytohormone Ethylene on Fruit Ripening

A Paper 3 experiment comparing how fast fruit ripens when exposed to the plant hormone ethylene from a ripe banana, versus fruit kept without it.

Comparing Biochemical Oxygen Demand (BOD) in Different Water Samples

How to measure and compare Biochemical Oxygen Demand as an indicator of organic pollution in different water samples.

Continuous and Discontinuous Variation in Humans

How to investigate and classify continuous variation, such as height, and discontinuous variation, such as tongue-rolling ability, among a group of students.

Paper 3 Answering Technique

How to approach the SPM Biology Paper 3 practical instrument, reading data, stating variables, writing hypotheses, tables, graphs, conclusions, and evaluation.