OrganisationVery High Exam FrequencyAQAEdexcelOCRWJEC

Transpiration

Transpiration process, stomatal control, factors affecting rate, plant adaptations, measuring transpiration, and practical investigations

What you'll cover

  • Transpiration definition and process
  • Stomata structure and guard cells
  • Guard cell mechanism: potassium ions and turgor
  • Factors affecting rate: temperature, humidity, wind, light
  • Transpiration stream function
  • Measuring with potometer
  • Xerophytic adaptations: thick cuticle, sunken stomata
  • Hydrophytic adaptations for water plants
  • CAM photosynthesis in desert plants
  • Functions: cooling, mineral transport, turgor maintenance

Sample Flashcards

What is a potometer?
An apparatus that measures the rate of water uptake by a plant shoot. Used to estimate transpiration rate (though actually measures uptake, not loss).
What is a xerophyte?
A plant adapted to survive in dry/arid conditions with limited water availability (e.g., cacti, marram grass).

Sample Questions

What is transpiration?

  • A. The evaporation of water from plant leaves through stomata
  • B. The movement of sugars through phloem
  • C. The absorption of water by root hair cells
  • D. The process of photosynthesis in leaves
1 markfoundation

Describe the three stages of transpiration in a leaf.

3 marksstandard

20

exam-style questions

25

revision flashcards

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