What important function do cilia and flagella have in cells?

Cilia and flagella play a crucial role in cell movement, primarily through the action of microtubules. These structures are composed of a specific arrangement of microtubules and proteins that enable them to move in a whip-like or sweeping motion. This movement can propel cells through fluid environments or move substances across the surface of stationary cells, such as mucus in the respiratory tract through cilia.

The mechanism behind this movement involves the sliding of microtubules against each other, driven by motor proteins. This contraction and relaxation lead to the bending and motion of cilia and flagella, which are essential for maintaining cellular functions and facilitating movement in a variety of organisms. Other options, such as photosynthesis, cell division, and energy production, do not directly involve cilia and flagella. Instead, these processes are carried out by different cellular components and mechanisms that are not related to the function of these structures.