Final answer:
Antibodies can bind to a bacterium's flagella, which interferes with its motility and helps prevent infection by limiting its ability to move.
Step-by-step explanation:
The binding of antibodies to flagella interferes with a bacterium's ability to swim, helping prevent infection. Flagella are structures used by cells, including bacteria, to move in aqueous environments. Bacterial flagella function like propellers, consisting of stiff spiral filaments composed of flagellin protein subunits. These flagella extend outward from the cell and rotate to propel the bacterium. When antibodies bind to these flagella, they can inhibit the bacterium's mobility, thereby reducing its ability to cause infection.