Exchange Surfaces | OCR A-Level Biology A (H420)
Exchange Surfaces
- 64 questions
- 5 subtopics
- Module 3: Exchange and transport
- Component 01 and Component 03
Exchange surfaces is the first section of Module 3, examined on Biological Processes.
It covers why surface area to volume ratio forces large organisms to develop exchange surfaces, the mammalian airways and how ventilation works, lung volumes measured on a spirometer, and gas exchange in fish and insects.
Sample questions from Exchange Surfaces
Answer each one closed book first, then open the answer.
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Surface area to volume and the features of an exchange surface
Why do multicellular organisms require specialised exchange surfaces?
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Their lower surface area to volume ratio combined with higher metabolic activity means simple diffusion across the body surface is inadequate to supply sufficient oxygen and remove waste products. -
Surface area to volume and the features of an exchange surface
Why is a thin barrier important for an efficient exchange surface?
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A thin barrier reduces the diffusion distance, allowing molecules to cross more rapidly according to Fick's law. -
The mammalian gas exchange system
What is the function of cartilage in the trachea and bronchi?
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Cartilage provides structural support to keep the airways open and prevent them from collapsing during pressure changes. -
The mammalian gas exchange system
In which parts of the respiratory system is smooth muscle found?
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In the walls of the trachea, bronchi and bronchioles. -
Ventilation and lung volumes
What happens to the diaphragm during expiration?
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The diaphragm relaxes and returns to its domed shape, decreasing the volume of the thoracic cavity. -
Ventilation and lung volumes
Define vital capacity.
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The maximum volume of air that can be exhaled after a maximum inhalation. -
Gas exchange in fish and insects
Define countercurrent flow in fish gills.
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A system where blood flows through the gill lamellae in the opposite direction to the flow of water over the gills. -
Gas exchange in fish and insects
Describe the structure of the insect tracheal system.
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A network of tubes called tracheae that branch into progressively smaller tubes called tracheoles, which deliver oxygen directly to the tissues.
The 5 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Surface area to volume and the features of an exchange surface | Why diffusion alone fails as an organism grows, the surface area to volume calculation, and the large area, thin barrier and steep gradient an exchange surface needs. | 12 |
| The mammalian gas exchange system | The route from trachea through bronchi and bronchioles to the alveoli, and the tissues lining it: smooth muscle, elastic fibres, goblet cells, cartilage and ciliated epithelium. | 14 |
| Ventilation and lung volumes | The intercostal muscles and diaphragm during inspiration and expiration, elastic recoil, and tidal volume, vital capacity and breathing rate from a spirometer trace. | 12 |
| Gas exchange in fish and insects | The operculum, gill filaments and lamellae and why countercurrent flow is efficient, together with the spiracles and tracheal system of an insect. | 12 |
| Dissecting and examining gas exchange tissue | Dissecting a bony fish and an insect, the rules of a good biological drawing, and the tissues visible in prepared slides of lung and trachea. | 14 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby sections
OCR A-Level Biology A Active Recall Guide
Every section, not just this one. 1,833 questions with their answers.