Plotting independent and dependent variables accurately, drawing lines of best fit.
Using a measuring cylinder to transfer small volumes (e.g., 1 cm³–5 cm³) introduces a high percentage error.
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 o level biology practical 2020 answers
The O Level Biology Practical 2020 series was unique. Conducted during a period of global disruption, the papers focused heavily on core, low-risk experiments that could be managed with minimal equipment. For current students, reviewing the is a goldmine of insight. The questions tested classic skills: food tests, osmosis in plant cells, enzyme activity (catalase), and microscope drawing.
Don’t just memorize answers. Learn why iodine turns blue-black (amylose helix trapping iodine) and why catalase works best at pH 7. That’s how you beat the 2021, 2022, and 2023 practicals too. For current students, reviewing the is a goldmine of insight
A major component of the 2020 paper involved identifying unknown nutrients in a given solution (Sample X) and investigating the effects of temperature or pH on enzyme-catalyzed reactions. 1. Benedict's Test for Reducing Sugars
Candidates investigated how temperature affects the leakage of red pigment through the cell membranes of beetroot cylinders. Observation For current students
The 2020 paper required students to perform standard food tests on unknown solutions extracted from biological specimens. Reagent Used Positive Result Negative Result Heating Required? Benedict's Solution →right arrow →right arrow Remains Blue Yes (Water bath) Starch Iodine Solution Blue-Black Remains Brown/Yellow Proteins Biuret Reagent Violet / Purple Remains Blue