Glucose does not efficiently diffuse directly through phospholipid bilayers. However, in the digestive tract, large quantities of glucose are moved from food, into the epithelial cells lining the small intestine, then out of these cells into the extracellular space and from there into the bloodstream. The relative concentrations of glucose in each of these compartments is as follows: Higher in the epithelial cell than in the food; Higher in the epithelial cell than in extracellular space; Higher in extracellular space than in bloodstream. Based on this information, predict the modes of transport used to move glucose 1) from food into the epithelial cell 2) From the epithelial cell into the extracellular space 3) From the extracellular space into the bloodstream.
A. Active transport; Simple diffusion; Simple diffusion
B. Active transport; Facilitated diffusion; Active transport
C. Active transport; Passive transport; Passive transport
D. Facilitated diffusion; Active transport; Passive transport