Required Practicals for Edexcel GCSE Biology

General Tips for Practical Exams

• Independent Variable: The variable you change in the experiment.
• Dependent Variable: The variable you measure that changes as a result.
• Control Variables: Factors kept constant to ensure accurate results.
• Equipment Usage: Always specify the equipment used for measurements (e.g., "measure with a ruler").
• Safety Precautions: Use goggles and gloves when working with chemicals.
• Accuracy of Measurements: Reduce errors/uncertainties (e.g., avoid parallax error by aligning eye with the measurement).
• Repeat Measurements: Perform multiple trials and calculate a mean to increase accuracy.
• Answer Format: Use bullet points for clarity and organization.

Biology Practical 1: Cells and Microscopes

• Preparation: Use a scalpel and tweezers to place onion skin on a slide; add iodine stain.
• Microscope Use: Start with the shortest objective lens and use coarse and fine focus knobs.
• Graticule: Use for measuring cell size in micrometers (1 micrometer = 1 x 10^-6 m).

Biology Practical 2: Enzymes

• Aim: Find the optimum temperature or pH for an enzyme (e.g., amylase).
• Method: Change temperature using a water bath or pH with buffer solutions.
• Measurement: Use a spotting tile with iodine to track starch breakdown.
• Analysis: Plot time vs. temperature or pH to find the optimum.

Biology Practical 3: Food Tests

• Preparation: Grind food with pestle, add distilled water.
• Tests:
  • Starch: Add iodine solution (black/purple indicates presence).
  • Glucose: Add Benedict's solution and heat (color change indicates sugar levels).
  • Protein: Add Biuret reagent (turns purple if protein is present).
  • Lipids: Add ethanol, then water (solution turns cloudy if lipids are present).

Biology Practical 4: Osmosis

• Aim: Determine sugar concentration in potato cells.
• Method: Use cylinders of potato in different sugar solutions.
• Analysis: Calculate percentage mass change and plot against solution concentration.

Biology Practical 5: Microbiology

• Cultures: Use agar plates for growing bacteria, use aseptic techniques.
• Antibiotics: Place paper discs with antibiotics on agar to observe zones of inhibition.
• Analysis: Measure and calculate areas of bacterial colonies or inhibition zones.

Biology Practical 6: Photosynthesis

• Aim: Investigate light intensity effect on photosynthesis.
• Method: Use pondweed and measure gas production.
• Analysis: Plot rate of photosynthesis against light distance (inverse square relationship).

Biology Practical 7: Respiration

• Aim: Measure oxygen absorption using respirometer.
• Method: Track liquid movement in graduated tube.
• Analysis: Use boiled peas and glass beads as controls.

Biology Practical 8: Field Work and Quadrats

• Method: Use quadrat for population estimates, random sampling.
• Transect Line: Study changes in population density over a gradient.
• Factors: Consider biotic and abiotic factors affecting populations.

• Additional Resources: Check out videos and playlists on practical demonstrations.