BRAINCAKEGas Exchange in Unicellular Organisms
Single-celled organisms have a large surface area to volume ratio because they are small. They can therefore exchange substances with their environment by simple diffusion.
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Key terms in this lesson
- prokaryotic cell
- A cell, such as a bacterium, that lacks a nucleus and membrane-bound organelles and has a single loop of circular DNA.
- diffusion
- The net passive movement of molecules or ions from a region of higher concentration to a region of lower concentration, down a concentration gradient.
- surface area to volume ratio
- The ratio of an organism's or structure's external surface area to its total volume, which decreases as size increases.
More in Exchange of Gases
- The Need for Specialised Exchange Surfaces
- Surface Area to Volume Ratio
- The Rate of Diffusion
- Features of A Specialised Exchange Surface
- Gas Exchange in Insects
- Diffusion Gradient
- Mass Transport
- Increasing the Rate of Diffusion
All 28 lessons in Exchange of Gases · All AQA AS-level Biology topics