Lesson 2: Membrane Dynamics & Transport Mechanisms
Choose and justify the membrane-transport mechanism operating in a cell context.
60-minute plan: retrieval 5 · media 10 · scenario task 25 · portfolio 15 · exit check 5
🎯 Ngā Whāinga Akoranga | Learning Intentions
The fluid mosaic model of the cell membrane, passive transport (simple diffusion, facilitated diffusion, osmosis), active transport, and endo/exocytosis.
Model phospholipid bilayer permeability, solve water potential gradient scenarios, and explain active transport pumps against concentration gradients.
🎥 Media Anchor & Pedagogical Scaffold
Cell Transport
Video: Amoeba Sisters (full runtime: 7m 50s).
🧠 1. Before Viewing (Activate & Predict)
How do cell membranes remain selectively permeable, allowing vital nutrients in while pumping metabolic wastes out?
👁️ 2. During Viewing (Watch With a Job)
- Watch for: Distinguish diffusion through the bilayer from facilitated diffusion through membrane proteins.
- Watch for: Explain why active transport requires ATP to move substances against a concentration gradient.
- Watch for: Record how osmosis changes plant and animal cells differently.
🗣️ 3. After Viewing & Kaiako Move (Process & Apply)
Kaiako move: Ask learners to classify one mechanism by gradient, membrane protein and ATP use.
Immediate task: Open Learner Evidence Pack · Sheet 2.
⚡ Whakaoho | Do Now: Cell Recall Challenge (5 mins)
Why salty chips make you thirsty. Nothing has left your body, yet within minutes you want water.
Two minutes: the salt is now in the fluid outside your cells. Say which way water moves and why, and use the words high and low water potential. Then predict what your cells look like before you drink — and what tells your brain you are thirsty.
📖 Activity 1: Core Process Investigation & Diagram Analysis (25 mins)
Membrane decision table (10 min). Use the supplied molecule cards to decide whether each substance crosses through the bilayer, uses facilitated diffusion or requires active transport. Justify with size, charge or polarity, gradient and ATP.
Tonicity scenarios (15 min). Complete all six supplied plant/animal-cell cases. Draw net water movement and predict the cellular consequence using precise vocabulary.
Supplied inputs
- Learner Evidence Pack · Sheet 2 — mechanism decision table and six tonicity scenarios
- Kaiako Guide · Lesson 2 — answer cues and misconception checks
📝 Activity 2: Portfolio evidence (15 mins)
Complete Portfolio Section 2 with one fully justified transport scenario. For the 5-minute exit check, explain why facilitated diffusion is passive even though it uses a protein.
🏫 Kaiako Planning & Pedagogy Notes
Level 2 Biology focus: the current specification allows facilitated diffusion. Require mechanism, direction and cell consequence rather than accepting a named process alone. See Kaiako Guide · Lesson 2.
Paired membrane-structure concept in Mechanism & Exam Synthesis →
Paired passive-transport concept in Mechanism & Exam Synthesis →