* Lipid soluble substances are able to diffuse freely across the [[Introduction to the Phospholipid Bilayer - Anatomy & Physiology|lipid bilayer of cells.]]
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* Lipid soluble substances are able to diffuse freely across the [[Phospholipid Bilayer - Anatomy & Physiology|lipid bilayer of cells.]]
* This occurs passively down the concentration gradient.
* This occurs passively down the concentration gradient.