O Level Biology Practical 2020 Answers Jun 2026

This section assessed microscopic or macroscopic observation skills. Students were provided with a biological specimen (such as a plant organ or cross-section) to sketch and calculate its magnification. Drawing Requirements

Measure the specified length on your drawing using a ruler (always work in millimeters, mm).

| Topic Area | Common Practicals | Key Variables & Observations | | :--- | :--- | :--- | | | Testing for starch, reducing sugars, proteins, and fats. | Observations: Color changes (e.g., blue-black for starch, brick-red precipitate for reducing sugars, violet for proteins, translucent spot for fats). | | Enzymes | Investigating the effect of temperature or pH on enzyme activity (e.g., catalase, amylase). | Independent Variable: Temperature or pH. Dependent Variable: Rate of reaction (e.g., time for a color change, volume of gas produced). Control: Boiled enzyme or without substrate. | | Osmosis & Diffusion | Investigating the effect of solute concentration on the mass or length of plant tissue (e.g., potato cylinders). | Independent Variable: Concentration of the solution. Dependent Variable: Change in mass or length of the tissue. Control: Distilled water (isotonic condition). | | Plant Biology | Examining leaf structure (stomata), root hair cells, or cross-sections of stems. | Observations: Identifying and labeling xylem, phloem, palisade mesophyll cells, guard cells, and stomata. | | Microscopy | Preparing and observing stained slides of onion cells or cheek cells. | Observations: Magnification calculation, drawing cells, labeling organelles (nucleus, cell wall, cytoplasm). | o level biology practical 2020 answers

Procedure : Add a few drops of iodine solution to the sample.

Procedure : Add equal volumes of Benedict's solution and the sample into a test tube. Heat in a boiling water bath for 3–5 minutes. | Topic Area | Common Practicals | Key

The factor you change deliberately (e.g., testing at 20°C, 30°C, 40°C, 50°C, and 60°C using regulated water baths).

2020 O-Level Biology Practical Guide | PDF | Flowers - Scribd | Independent Variable: Temperature or pH

To observe mitosis in root tips.

Ultimate Guide to the 2020 O Level Biology Practical: Key Experiments, Answers, and Exam Strategies