| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Biology |
| Lesson Topic: explain how companion cells transfer assimilates to phloem sieve tubes, with reference to proton pumps and cotransporter proteins |
Learning Objective/s:
- Describe the structure and function of companion cells and sieve‑tube elements.
- Explain how the H⁺‑ATPase creates a proton‑motive force for apoplastic loading.
- Illustrate the action of sucrose‑H⁺ symporters and amino‑acid‑H⁺ antiporters in transporting assimilates.
- Analyse the step‑by‑step mechanism of apoplastic phloem loading.
- Compare apoplastic and symplastic loading strategies.
|
Materials Needed:
- Projector and screen
- PowerPoint slides with diagrams of phloem loading
- Handout worksheet for labeling the loading steps
- Microscopy images of leaf cross‑section (phloem)
- Whiteboard and markers
- Clickers or online quiz platform for formative checks
|
Introduction:
Imagine a plant moving the sugar you just ate from a leaf to its roots. Students should already know basic concepts of photosynthesis and active transport. Today they will learn how companion cells use a proton pump and cotransporters to load sucrose into sieve tubes. Success will be measured by their ability to diagram and explain the process.
|
Lesson Structure:
- Do‑now quiz on active transport (5')
- Mini‑lecture with slides on phloem anatomy and companion cell role (10')
- Interactive animation of H⁺‑ATPase and sucrose‑H⁺ symporter, followed by Q&A (8')
- Guided worksheet: groups label each step of apoplastic loading (12')
- Think‑pair‑share comparing apoplastic vs. symplastic loading (5')
- Formative check using clicker questions; clarify misconceptions (5')
|
Conclusion:
We will recap the proton‑pump driven loading cycle and its importance for long‑distance transport. For the exit ticket, each student writes one sentence describing how the proton gradient powers sucrose uptake. Homework: read the textbook section on phloem transport and complete the online quiz.
|