L Pretest: Unit 5 Gas exchange takes place across the membranes of the alveoli and the
capillaries. How do the structures of these membranes improve the efficiency
of this process?
AIK
Bronchiole,
Alveo
Small blood
vessels (capillaris)
A. Pores in the membranes allow oxygen to move out of the alveoli's
cells and carbon dioxide to move into the cells.
O B. The shapes of the membranes slow blood flow, allowing more
time for gas exchange
O C. The shapes of the alveoli and the capillaries increase the surface
area of the membranes.
O D. The membranes have proteins that transport carbon dioxide and
oxygen against the concentration gradients.