Facilitated diffusion
<span>The word 'diffusion' means free movement across distance, with or without the presence of a barrier. However, there is a phenomenon known as facilitated diffusion which occurs at the cellular level. The cell does not allow free radicals and other harmful substances to enter and harm the cell organs. This is possible due to the structure of the cell membrane. The structure is such that, it allows only certain things to pass in and out of the cell. One such activity that allows selective movement in and out of the cell is the process of facilitated diffusion.</span>
        
             
        
        
        
The physiological process occurring in the muscle cells that account for the gradual onset of muscle fatigue is called anaerobic the body is breaking down oxygen after than it can get in.
        
             
        
        
        
Answer:
A.
Explanation:
 bacteria have cell membranes to mimic a normal cell. this protects the bacteria from being consumed by the body's natural defences .