A Level Biology Practice Exam

What is the function of the operculum in bony fish?

1. To protect the heart

2. To regulate water intake

3. To cover the gills and maintain water flow

4. To assist in the buoyancy of the fish

The correct answer is: To cover the gills and maintain water flow

The function of the operculum in bony fish is to cover the gills and maintain water flow. The operculum is a bony flap that protects the delicate gill structures located behind it. By moving the operculum, fish can create a pressure difference that allows water to flow over the gills, facilitating gas exchange—specifically the uptake of oxygen and the release of carbon dioxide. This movement is vital for the respiration of the fish, ensuring they can efficiently extract oxygen from the water. Understanding the operculum’s role underscores the overall respiratory system of bony fish, which relies on the continuous flow of water over the gills. The operculum not only serves as a protective barrier but also plays an important part in maintaining that flow, especially when the fish is at rest or not actively swimming.