Final answer:
Cilia use ATP as an energy source to power the beating motion, which is facilitated by motor proteins walking on microtubule tracks within the cilia, enabling them to carry out various biological functions.
Step-by-step explanation:
The cilia use ATP to power their movement through interactions of motor proteins and microtubules within the ciliary structure. This movement is critical for various functions in living organisms, such as moving fluids and trapped particles across cell surfaces.
When ATP is hydrolyzed, it releases energy which is then employed by motor proteins like dynein within the cilia, allowing them to 'walk' along the microtubules. This process causes the sliding of microtubules against one another, resulting in the characteristic beating motion of the cilia. These structures are essential for functions ranging from the circulation of cerebrospinal fluid in the brain to clearing mucus in the respiratory tract.