Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Biology
Lesson Topic: explain the role of auxin in elongation growth by stimulating proton pumping to acidify cell walls
Learning Objective/s:
  • Describe the acid‑growth hypothesis and how auxin initiates proton pumping.
  • Explain the molecular sequence from auxin perception to cell‑wall acidification.
  • Interpret experimental evidence linking H⁺‑ATPase activity to cell elongation.
  • Predict the effect of proton‑pump inhibitors on plant growth.
  • Design a simple experiment to measure apoplastic pH changes after auxin treatment.
Materials Needed:
  • Projector and screen
  • PowerPoint slides with diagrams
  • Printed handout of the sequence table
  • pH‑indicator strips for a quick demo
  • Sample pea stem segments
  • Whiteboard and markers
  • Laptop with internet access
 Introduction:
Begin with a short video of a plant shoot bending toward light, prompting students to think about how cells elongate. Recall that auxin is the hormone driving differential growth and that students already know about its polar transport. Today they will be able to explain how auxin activates proton pumps to acidify the cell wall and predict the outcome of experimental manipulations.
Lesson Structure:
  1. Do‑now (5') – students answer a quick question on hormone‑mediated growth.
  2. Mini‑lecture (10') – present auxin perception, the acid‑growth hypothesis, and the proton‑pumping mechanism with slides.
  3. Guided analysis (10') – in pairs, complete a partially‑filled sequence table of events.
  4. Demonstration (10') – show pH‑indicator strips changing colour on pea stem segments treated with IAA.
  5. Data interpretation activity (10') – groups examine experimental evidence and answer guided questions.
  6. Check for understanding (5') – exit ticket: write one sentence describing how proton pumping leads to cell elongation.
Conclusion:
Recap that auxin triggers H⁺‑ATPase activation, acidifying the wall and allowing turgor‑driven expansion. Collect the exit tickets and remind students that the key idea is the link between hormone signaling and physical cell changes. For homework, ask them to draft a brief lab plan to test the effect of an H⁺‑ATPase inhibitor on seedling growth.