Biology Year 11 - Module 2 - Lesson 15
Gas Exchange Between Internal and External Environments
1. Key Ideas
Before we explain the mechanism, look at the data. The numbers tell a story about gradients, distances, and surfaces — and if you read them right, you'll understand the mechanism before you've been taught it.
- Define partial pressure and explain how it drives gas exchange
- Explain gas exchange between the internal and external environments
2. Success Criteria
By the end, you should be able to:
- Define partial pressure and explain how it drives gas exchange
- Trace O₂ and CO₂ movements from external air to mitochondria
- Explain the role of the cardiovascular system in maintaining gradients
3. Key Terms
4. Activity: Build the Lesson Map
Use the lesson to complete the table. Keep answers brief but specific.
| Prompt | Your answer |
|---|---|
| Main concept | |
| Important example | |
| Common mistake to avoid | |
| How this links to the next lesson |
5. Short Answer Questions
1. 6. Explain the role of blood flow in maintaining efficient gas exchange across the alveolar membrane. In your answer, describe what would happen to gas exchange if blood flow stopped.
2. 7. Use Fick's law to explain how pulmonary oedema (fluid accumulation between alveoli and capillaries) impairs gas exchange.
3. 8. Distinguish between external gas exchange and internal gas exchange. In your answer, state where each occurs, which gases move in which direction, and what drives each exchange.
6. Extend: Apply the Idea
A student gives a memorised answer about Gas Exchange Between Internal and External Environments but does not use evidence or reasoning.
Improve the answer by writing a stronger response that uses accurate terminology, a relevant example and a clear explanation.
7. Multiple Choice
1. What is the best first step when answering a question about Gas Exchange Between Internal and External Environments?
A. Identify the key concept being tested
B. Write every fact from memory
C. Ignore the command word
D. Skip examples and evidence
2. Which answer would show stronger understanding of Gas Exchange Between Internal and External Environments?
A. An answer with accurate terms and reasoning
B. A copied definition only
C. A single-word response
D. An answer with no example
3. What should you do if a question asks you to explain?
A. Link the idea to a reason or cause
B. List unrelated facts
C. Only draw a diagram
D. Write the shortest possible answer
8. Success Criteria Proof
Finish with evidence that you can do each success criterion.