O Level Biology Practical 2020 Answers -

| Skill Area | Self-Assessment | |------------|-----------------| | Drawing biological diagrams | Need practice / Confident | | Plotting and interpreting graphs | Need practice / Confident | | Identifying experimental variables (independent, dependent, controlled) | Need practice / Confident | | Writing valid conclusions | Need practice / Confident | | Suggesting controls and improvements | Need practice / Confident |

To prepare effectively, review the 2020 papers from official sources.

Avoid vague language. Write "brick-red precipitate" instead of "red color," and use words like "denatured," "kinetic energy," "concentration gradient," and "surface area-to-volume ratio."

If your drawing measures 30 mm and the actual specimen is 10 mm, the magnification is ×3cross 3 4. Sources of Error and Improvements o level biology practical 2020 answers

Forgetting to state that heating/a boiling water bath is mandatory. Writing "red solution" instead of "brick-red precipitate" resulted in a loss of precision marks. 2. Biuret Test for Proteins

Shortest time to change colour (~26s), indicating highest glucose concentration (~0.95 g/dm³).

To ensure maximum marks in future practical examinations, keep these fundamental tips in mind: Sources of Error and Improvements Forgetting to state

You investigated how temperature affects the release of red pigment from beetroot cells. Higher temperatures generally cause more cell membrane damage, leading to a darker red color in the surrounding water.

Paper 3 requires candidates to physically perform experiments, record observations, and draw conclusions. Paper 4 (Alternative to Practical) is a written assessment designed for candidates who have previously completed practical work but sit a theory-based exam.

| Sucrose (M) | Final length (mm) | Change (mm) | | :--- | :--- | :--- | | 0.0 | +3 | Increase | | 0.2 | +1 | Increase | | 0.4 | 0 | No change | | 0.6 | -2 | Decrease | | 0.8 | -4 | Decrease | Biuret Test for Proteins Shortest time to change

Format the final answer clearly with the multiplication prefix (e.g., ×40cross 40 Core Practical Strategies for Future Candidates

For a setup testing the effect of pH, you would need to use buffer solutions to maintain specific pH levels while keeping temperature and substrate concentration constant. 2. Food Tests & Glucose Concentration

A student added 2 cm³ of hydrogen peroxide to 1 cm³ of potato extract. Effervescence was seen. The glowing splint rekindled. Explain why.

: Students performed the Benedict’s test. Successful responses required a structured table with correct headings (e.g., sample name, time taken for color change, and final glucose concentration).