AP BIOLOGY

Detailed explanation-1: -Gills are highly folded, giving them a large surface area and maximising the efficiency of gas exchange. The gill filaments have many protrusions called gill lamellae.

Detailed explanation-2: -The total surface area of secondary lamellae per 1 g of body weight is from about 193 to 159 mm2.

Detailed explanation-3: -Gill lamellae are the tiny branches that extend from the gill filaments, greatly increasing the surface area, through which water moves through the gills.

Detailed explanation-4: -Larger things, like fish, have to collect all the oxygen in one area (gills for the fish) and transport it to every cell (in blood for the fish). The more surface area there is in the gills, the more oxygen can be absorbed.