O Level Biology Practical 2020 Answers Jun 2026

Let me know if you would like me to unpack a from this syllabus, detail the step-by-step graphing rules required by Cambridge examiners, or explain a particular biochemical mechanism in deeper detail. Share public link

At 0 minutes, the iodine solution turns blue-black, indicating the presence of starch. As time progresses, the color transitions to brown, and finally remains yellow-orange. This indicates that all starch has been fully hydrolysed into maltose by the amylase enzyme.

Using a stopwatch to measure the time for the disappearance of the blue-black color with iodine. D. Osmosis Investigation o level biology practical 2020 answers

Water moved into potato cells by osmosis down a water potential gradient, making cells turgid (increase in length/mass).

These write-ups are just a sample and may not reflect the exact questions and experiments in your O-Level Biology Practical 2020. However, they should give you an idea of how to approach and answer practical questions. Make sure to follow the instructions and guidelines provided by your teacher or the exam board. Good luck with your exams! Let me know if you would like me

Candidates were required to vary an independent variable—such as enzyme concentration, substrate concentration, or temperature—and measure the volume of oxygen gas produced within a specific timeframe, or record the time taken for a uniform reaction marker (e.g., a floating disk) to rise. Key Expected Answers and Data Trends

Acid Treatment (pH 2) : The banana slice remained creamy yellow because the highly acidic environment denatured the polyphenol oxidase enzymes, rendering them inactive. This indicates that all starch has been fully

: Students used the Benedict’s test , recording the time taken for the first color change to occur. Sample Results :

Improvement: Submerge reaction test tubes into a thermostatically controlled water bath to maintain a uniform temperature. Question 2: Plant Tissue Osmosis and Biological Drawings

Clear, sharp, continuous single lines (no sketching or shading).

Before we dive into answers, it's crucial to understand the structure of the practical exams. The Cambridge O Level Biology (5090) syllabus includes two distinct practical components: