The rate of diffusion of glucose through artificial phospholipid bilayers is exceptionally low. By contrast, the cells lining the small intestine rapidly transport large quantities of glucose from glucose-rich food into their glucose-poor cytoplasm. Based on this information, which transport mechanism is most likely responsible for glucose transport in the intestinal cells?

Facilitated diffusion

Explanation:

Facilitated diffusion is a type of passive down the concentration gradient transport that uses trans-membrane proteins to facilitate the transport of polar, charged and large substances that otherwise cannot cross the non-polar core of the lipid bilayer of the membrane. Channels and carrier proteins are involved in facilitated diffusion.

Channel proteins make a path to allow the substance to cross the membrane while conformation changes in the carrier proteins transport the substances across the membrane. Since facilitated diffusion occurs via channel and carrier proteins, it is a relatively fast process as compared to simple diffusion.

According to the given information, down the concentration gradient transport of glucose is much faster in the small intestine as compared to the one across the artificial lipid bilayer. This suggests that glucose is being transported by facilitated diffusion across the lining of the small intestine.