Required Practicals

Question 1

How do you do the microscopy practical?

Answer 1

1. Place a thin slice of specimen on a microscope slide. 2. Add a drop of iodine or another stain. 3. Carefully place a coverslip on top using a mounted needle. 4. Place the slide on the microscope stage. 5. Start with the lowest magnification lens and focus using the coarse adjustment knob, then use the fine adjustment knob for clarity. 6. Draw what you see and label the cell structures.

Question 2

How do you do the osmosis practical?

Answer 2

1. Cut equal-sized potato cylinders. 2. Measure their initial mass. 3. Place them in different concentrations of sugar or salt solution (e.g. 0%, 10%, 20%). 4. Leave them for at least 30 minutes. 5. Remove, dry, and reweigh each one. 6. Calculate percentage change in mass to see where osmosis has occurred. 7. Plot a graph of percentage change against concentration.

Question 3

How do you do the enzyme activity practical?

Answer 3

1. Set up a water bath at 35–40°C. 2. Add iodine to spotting tiles to test for starch. 3. In a test tube, mix amylase, starch, and buffer solution at a specific pH. 4. Start a timer. 5. Every 30 seconds, take a drop and add it to iodine on the tile. 6. When iodine stays orange (no starch), stop the timer. 7. Repeat for different pH values to see how pH affects enzyme activity.

Question 4

How do you do the food tests practical?

Answer 4

1. Prepare a food sample by grinding it in water. 2. For starch: add iodine – blue-black means starch is present. 3. For sugar: add Benedict’s solution and heat – brick red means high sugar. 4. For protein: add Biuret solution – purple means protein is present. 5. For lipids: add ethanol then water – cloudy white layer means lipids are present.

Question 5

How do you do the photosynthesis practical?

Answer 5

1. Place a piece of pondweed (like Elodea) in a beaker of water with a light source at a set distance. 2. Add sodium hydrogen carbonate to provide carbon dioxide. 3. Allow it to adapt for a few minutes. 4. Count the number of oxygen bubbles released per minute. 5. Repeat at different distances from the light. 6. Keep variables like temperature and CO₂ levels constant. 7. Use results to draw a rate of photosynthesis graph.