Biology Required Practicals

Microscopy Method

• Prepare a clean microscope slide.

• Place a small drop of water on the slide.

• Use forceps to place a thin layer of tissue (e.g., onion skin) onto the water.

• Add a drop of iodine solution to the tissue to stain it.

• Place a cover slip at a 45° angle to prevent air bubbles.

• Place the slide on the microscope stage and use the low-power objective lens to focus.

• Switch to the high-power objective lens to examine the details of the cells.

• Record your observations.

Microbiology Method

• Sterilize a petri dish with agar using an autoclave or heat.

• Inoculate the agar with a bacterial culture (e.g., E. coli) using a sterile swab.

• Place antibiotic discs on the agar surface at set distances from each other.

• Seal the petri dish and incubate it at 37°C for 24-48 hours.

• Measure the size of the zone of inhibition (the clear area around the antibiotic discs).

• Record the effectiveness of the antibiotics based on the size of the inhibition zones.

Osmosis Method

• Cut potato cylinders to the same size using a cork borer.

• Measure and record the initial mass of the potato cylinders.

• Prepare different concentrations of sucrose solutions (e.g., 0%, 10%, 20%, 30%).

• Place one potato cylinder in each solution.

• Leave the cylinders in the solutions for a set period (e.g., 30 minutes to 1 hour).

• Remove the potato cylinders, blot them dry, and remeasure their mass.

• Calculate the percentage change in mass for each cylinder.

Food Tests Method

• Test for Starch: Add a few drops of iodine solution to the food sample. A blue-black color indicates starch.

• Test for Reducing Sugars: Add Benedict’s solution to the sample, heat in a water bath. A color change from blue to green, yellow, or red indicates reducing sugars.

• Test for Proteins: Add Biuret solution to the sample. A purple color indicates the presence of protein.

• Test for Lipids: Mix the sample with ethanol and shake. Add water. A white emulsion indicates the presence of lipids.

Enzymes Method

• Prepare a starch solution by dissolving starch in warm water.

• Add a few drops of iodine solution to a separate test tube.

• Set up a water bath at the desired temperature (e.g., 20°C, 40°C, 60°C).

• Add amylase solution to the starch solution and start a timer.

• Every 30 seconds, remove a sample of the solution and drop it into the iodine solution.

• Record the time at which the iodine solution no longer changes color, indicating that all the starch has been broken down.

• Repeat the experiment at different temperatures or pH values, adjusting with a buffer solution.

Photosynthesis Method

• Set up a beaker of water with an aquatic plant (e.g., Elodea).

• Place the plant under a light source and measure the rate of photosynthesis by counting the oxygen bubbles produced by the plant.

• Measure the light intensity at different distances from the plant.

• Repeat the experiment at various distances (e.g., 5 cm, 10 cm, 15 cm).

• Record the rate of oxygen production for each light intensity.

Reaction Time Method

1. Ask the participant to place their hand at the bottom of a vertically held ruler.

2. Drop the ruler without warning and ask the participant to catch it as quickly as possible.

3. Record the distance the ruler falls before the participant catches it.

4. Repeat the test multiple times for each participant.

5. Calculate reaction time using a standard reaction time table.

Plant Responses Method

• Place two groups of plants in different environments:

  • Phototropism: Place one group of plants in a box with a single light source, so they grow towards the light.

  • Geotropism: Place another group of plants horizontally to observe their growth direction in response to gravity.

• Measure and record the direction and growth of the plants over several days.

• Compare the results to determine the effect of light and gravity on plant growth.

Field Investigation Method

• Choose a suitable habitat (e.g., a grassy field, woodland).

• Lay a transect line or use a quadrat to sample different areas within the habitat.

• Record the species and number of organisms in each quadrat.

• Measure environmental factors such as temperature, humidity, or soil pH at each sampling point.

• Analyze the data to determine factors affecting organism distribution.

Decay Method

• Prepare containers with decaying organic material (e.g., fruit or leaves).

• Set up different conditions (e.g., varying temperature, moisture, or oxygen supply).

• Measure the mass of the material at regular intervals.

• Observe changes in temperature or gas production using a thermometer or gas syringe.

• Record the rate of decay under different conditions.