Required Practical Investigations

Required Practical Investigations

1. Using a Potometer

Aim: Investigate factors affecting the rate of water uptake by plants

Method:

1. Cut a shoot underwater to prevent air bubbles entering xylem
2. Set up potometer ensuring all connections are airtight
3. Allow air bubble to form in capillary tube
4. Record bubble position and start timer
5. Measure distance bubble travels in set time periods
6. Calculate rate = distance ÷ time

Variables to investigate:

• Temperature - higher temperatures increase transpiration rate
• Humidity - lower humidity increases transpiration rate
• Air movement - wind increases transpiration rate
• Light intensity - light opens stomata, increasing transpiration

2. Tracking Water Transport with Dye

Aim: Observe the pathway of water transport in plants

Method:

1. Cut celery stalks or white flowers under running water
2. Place immediately in colored dye solution (food coloring)
3. Observe color changes over time
4. Cut sections to see dye distribution
5. Use microscope to observe xylem vessels

Results: Dye travels up through xylem vessels, proving water transport pathway

3. Microscopy of Plant Transport Tissues

Aim: Observe and compare xylem and phloem structure

Method:

1. Prepare thin cross-sections of plant stems
2. Stain with appropriate dyes (lignin stains red with phloroglucinol)
3. Observe under light microscope
4. Identify xylem and phloem tissues
5. Draw and label structures observed

Safety: Handle microscope slides carefully, be cautious with staining solutions