BRAINCAKEDiffusion Gradient
For rapid diffusion to take place, there has to be a steep diffusion gradient maintained in one direction.
As oxygen is delivered to the cells from the tracheoles it diffuses across the cell membranes into respiring cells and is used up in respiration, so a steep concentration gradient is maintained between the cells and the tracheoles.
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Key terms in this lesson
- diffusion
- The net movement of molecules or ions from a region of higher concentration to a region of lower concentration, down a concentration gradient.
- tracheole
- A fine, thin-walled tube branching from the tracheae in an insect's tracheal system, which carries gases directly to respiring tissues.
More in Exchange Surfaces and Breathing
- Lung Volume
- Breathing Rate and Ventilation Rate
- Gas Exchange in Unicellular Organisms
- Gas Exchange in Insects
- Mass Transport
- Increasing the Rate of Diffusion
- Limitations of the Tracheal System
- Gas Exchange in Fish
All 24 lessons in Exchange Surfaces and Breathing · All OCR AS-level Biology topics