Biology paper 1 required practicals

Microscopy (Onion Cells) Method

Peel a thin layer of epidermal tissue from an onion, place it on a glass slide, add iodine solution, cover with a coverslip at an angle, and observe using a microscope at a low power objective lens. Include a magnification scale.

Microbiology (Triple Only - Antibiotics) Method

Clean the workbench with disinfectant, work near a flame, sterilise an inoculating loop, spread a bacterial culture on agar, place antibiotic discs, tape the lid partially, and incubate at 25°C for 48 hours. Measure the inhibition zone diameter and calculate area.

Osmosis (Potato Cylinders) Method

Cut potato cylinders, measure initial mass, place in boiling tubes with sugar solutions, wait, blot, measure final mass and calculate percentage change in mass. Independent variable: sugar concentration; dependent: % mass change.

Food Tests Preparation

Grind food with pestle, add distilled water, stir, filter. Tests: Sugars (Benedict's), Starch (iodine), Proteins (Biuret), Lipids (Sudan III or ethanol test).

Effect of pH on Amylase Method

Add iodine drops to a spotting tile, mix amylase, starch, buffer in a tube, incubate at 35°C, sample every 10 or 30 seconds until iodine stays orange-brown. Record the time. Test different pH buffers for optimum pH.

Photosynthesis (Pondweed) Method

Place pondweed in a tube with sodium hydrogen carbonate, set an LED light at a distance, count oxygen bubbles in 1 minute after 5 min stabilization. Repeat at different distances for mean results.