Final answer:
If the cilia on a mollusk's gills do not work, it would have serious consequences on the mollusk's ability to breathe and survive.
Step-by-step explanation:
If the cilia on a mollusk's gills did not work, it would have serious consequences on the mollusk's ability to breathe and survive. The cilia on the gills of mollusks play a crucial role in the exchange of gases between the mollusk's blood and the surrounding water. They help to increase the surface area available for gas exchange and facilitate the movement of gases into and out of the body.
If the cilia on the gills did not work, the mollusk would not be able to efficiently absorb oxygen from the water and release carbon dioxide. This would lead to oxygen deprivation and a buildup of carbon dioxide in the body, which can be toxic. The mollusk may experience respiratory distress, become weak, and eventually die.