O Level Biology Practical 2020 Answers ((top)) -

The 2020 O Level Biology Practical exams varied by exam board. The most common boards were Cambridge (5090) and the Singapore-Cambridge (6093) SEAB syllabus. 🔬 SEAB (Singapore) 6093/03 Summary

• Isotonic at ~0.4 M (0% change). Lower conc → water enters (mass increases); higher conc → water leaves (mass decreases). Explain by water potential gradient between potato cells and solution.

: Higher temperatures damage the cell membrane (denaturing membrane proteins), making it more permeable and allowing more pigment to leak out. Controlled Variables o level biology practical 2020 answers

O Level Biology Practical 2020: Experiment 3 - Investigating Photosynthesis The 2020 O Level Biology Practical exams varied

• Control Variables: The 2020 answer key was notoriously specific about variables. It wasn't enough to say "keep temperature constant"; students had to specify how (e.g., "using a water bath thermostatically controlled at 37°C").
• Range of Values: Many students lost marks for not providing a specific range. Correct answers listed specific intervals (e.g., "temperatures of 10°C, 20°C, 30°C, 40°C, and 50°C") rather than vague statements like "different temperatures."
• Repetition: The phrase "repeat the experiment to calculate an average" was a standard requirement in the answer key. Failure to mention reliability resulted in lost marks.

Calculation Tip: If your drawing measures 30 mm and the actual specimen is 10 mm, the magnification is ×3cross 3 4. Sources of Error and Improvements Isotonic at ~0