In which process is “surface area” of key importance for humans?

A. Reabsorption of glucose in the proximal convoluted tubule
B. Release of surfactants by type I pneumocytes
C. Display of antibodies by red blood cells
D. Secretion of enzymes by villi of the small intestine

A

This question was difficult, but also a good discriminator. Many candidates wrongly believed that surface area affects the secretion of enzymes in the villi. This is not true, as surface area affects the absorption of substances, not the secretion of enzymes.