What is the primary purpose of the flagellum in a cell?

The primary purpose of the flagellum in a cell is movement. Flagella are long, whip-like structures that propel cells, allowing them to swim through fluid environments. This is particularly evident in various unicellular organisms, such as sperm cells in animals or certain bacteria, where the flagellum provides mobility to navigate toward resources or away from harmful substances. The ability to move is crucial for these cells to fulfill essential life functions, such as seeking nutrients and escaping adverse conditions, underscoring the flagellum's role as a key organelle for locomotion.