O Level Biology Practical 2020 Answers File

Due to the COVID-19 global pandemic, students did not sit exam papers in the June 2020 series. However, Cambridge International still published the mark schemes to support teachers and students in their preparations.

Students were required to analyze an unknown solution (often labeled Solution X) to determine its nutrient composition. :

Now, let's imagine some possible answers to common questions that might be asked in the O-level biology practical exam:

Cambridge examiners look for specific criteria in biological diagrams: o level biology practical 2020 answers

2020 O-Level Biology Practical Guide | PDF | Flowers - Scribd

| 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). |

The correct apparatus is a or a pipette (typically a 50 cm³ measuring cylinder). A burette could also be accepted for accurate measurement. Candidates should specify the volume range appropriate for 50 cm³. Due to the COVID-19 global pandemic, students did

Chlorophyll is necessary for photosynthesis to produce starch. 3. Specimen Observation and Classification

This question tests your ability to use universal indicator paper correctly and record a value.

An analytical point often tested: Benedict’s test is semi-quantitative. A brick-red precipitate indicates a high concentration of reducing sugars, whereas a green or yellow color indicates a trace or moderate amount. Biological Drawing and Magnification : Now, let's imagine some possible answers to

Since many students could not take physical exams in June 2020 due to the pandemic, Paper 6 focused on analyzing data and planning. TeachifyMe Enzyme Activity

If the experiment involved sugar/salt solutions, students needed to explain that water moved out of the tissue via osmosis because the external solution had a lower water potential, rendering the tissue flaccid.

Control Variables : The length of the beetroot cylinders (30 mm) and the volume of water added above the cylinder must be kept constant to ensure a fair test.

: As temperature increased, the surrounding water became a progressively darker shade of red. Expected Answers & Scientific Explanation :