To increase the effectiveness of exchange surfaces lining the lungs and the intestines, evolutionary pressures have
A) increased the exchange surface area with folds and branches.
B) increased the thickness of the membranes in these linings.
C) increased the number of cell layers in these linings.
D) decreased the metabolic rate of the cells in these linings.
E) increased the volume of the cells in these linings.

Question

Quizplus · Accepted Answer

The effectiveness of exchange surfaces can be increased by increasing the surface area available for exchange. This can be achieved through folding and branching of the surface, providing more area for gases or nutrients to diffuse across. This is seen in alveoli in the lungs and villi in the intestine. Increasing the thickness of the membranes, increasing the number of cell layers or decreasing the metabolic rate of the cells would all have negative effects on the efficiency of the exchange surface. Increasing the volume of the cells would not necessarily affect the surface area available for exchange.

To Increase the Effectiveness of Exchange Surfaces Lining the Lungs