Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

What are cilia?

1. Muscle cells in the lungs

2. Hair-like projections on cell surfaces

3. Structures that help with oxygen exchange

4. Components of blood

The correct answer is: Hair-like projections on cell surfaces

Cilia are hair-like projections that extend from the surface of many types of cells. They play a critical role in various biological functions by moving fluids, such as mucus, over cell surfaces, which is particularly important in the respiratory system. Cilia help to clear pathogens and debris from the airways, thus contributing to respiratory health. In addition, cilia are involved in signaling pathways and can assist in the movement of cells themselves in certain contexts, such as within reproductive systems or in some unicellular organisms. The structure of cilia allows them to beat in a coordinated fashion, facilitating effective movement and transport functions. Other options do not accurately describe cilia; for instance, muscle cells are different structures responsible for contraction, while oxygen exchange occurs at the alveolar level in the lungs rather than through cilia themselves. Components of blood refer to elements like red blood cells, white blood cells, and platelets, which are unrelated to the structure and function of cilia. Thus, the option describing cilia as hair-like projections on cell surfaces is the most accurate representation of their nature and function.