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Learn: Gas Exchange Surfaces and Fick’s Law
Edexcel A Level Biology SNAB A
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Welcome!Today we'll explore gas exchange surfaces and Fick’s Law. These concepts are important for understanding how organisms exchange gases effectively. Let’s break it down step by step!
What are Gas Exchange Surfaces?Gas exchange surfaces are specialised areas where oxygen and carbon dioxide are exchanged between an organism and its environment. They are typically thin, moist, and have a large surface area to maximise efficiency.
Key Features of Effective Gas Exchange SurfacesGas exchange surfaces share common adaptations to optimise gas movement:Thin walls for a short diffusion distance.Large surface area to allow more gases to pass through.Moist surfaces to dissolve gases, aiding diffusion.Good blood supply to maintain concentration gradients.
Which feature of gas exchange surfaces reduces the diffusion distance?
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Introducing Fick’s LawFick’s Law describes how the rate of diffusion depends on several factors. It is expressed as:Rate of diffusion = (Surface Area × Concentration Difference) / ThicknessThis means diffusion is faster if surface area and concentration difference are high, but slower if the surface is thick.
Fick’s Law states that the rate of diffusion increases if the {{blank0}} is larger and the {{blank1}} is smaller.
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Example: Human LungsThe alveoli in human lungs are a great example of efficient gas exchange surfaces. They have a large surface area, are one cell thick, and are surrounded by capillaries to maintain concentration gradients.
Match the items on the left with their correct pairs on the right
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Review Time!Great work! You've learned about the features of gas exchange surfaces and Fick’s Law. Now let’s test your understanding with a few questions.
Which of the following improve diffusion efficiency? (Select all that apply)
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Match the items on the left with their correct pairs on the right
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Why are moist surfaces important for gas exchange?
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Well Done!You've completed the lesson on gas exchange surfaces and Fick’s Law. Keep practising to solidify your understanding!
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