This diagram covers Measuring Transpiration within Transpiration for GCSE Biology. Transpiration process, stomatal control, factors affecting rate, plant adaptations, measuring transpiration, and practical investigations It is section 6 of 20 in this topic. Focus on the labels, the relationships between parts, and the explanation that turns the diagram into an exam-ready answer.
Topic position
Section 6 of 20
Practice
20 questions
Recall
25 flashcards
Measuring Transpiration
1. Potometer Method
Setup:
- Cut shoot underwater to prevent air bubbles
- Assemble potometer apparatus underwater
- Ensure all joints are airtight
- Allow plant to equilibrate (5-10 minutes)
- Introduce air bubble at end of capillary tube
Measurement:
- Mark bubble starting position
- Time bubble movement along scale
- Calculate rate: distance ÷ time
- Reset bubble using reservoir
Limitations:
- Measures water uptake, not transpiration directly
- Assumes uptake = transpiration (mostly true)
- Cut shoot behaves differently than intact plant
2. Mass Loss Method
- Setup: Pot plant with sealed soil surface
- Method: Weigh at intervals, calculate water loss
- Advantage: Measures actual transpiration
- Disadvantage: Less sensitive than potometer
3. Cobalt Chloride Paper
- Principle: Blue when dry → pink when wet
- Use: Compare water loss from upper/lower leaf surfaces
- Qualitative: Shows presence, not rate
