(Solved): Which of the following are TRUE, regarding Gas exchange in fish. More than one answer may be true. ...

Which of the following are TRUE, regarding Gas exchange in fish. More than one answer may be true. Fish use a buccal positive pressure pump, and an opercula negative pressure pump to constantly ventilate the gill. In some fish, swimming with an open mouth may increase drag, but greatly reduces the metabolic cost of ventilation. Oxygen extraction is enhanced by matching flow of water across the gill, to equal both the direction and rate of blood flow through the secondary lamellae. The surface area for gas exchange can be regulated by changing the supply of blood to different regions of the gill.