If the inner surface of the ileum in the human small intestine was smooth, rather than being folded and subdivided into villi, which of the following statements would be true?

Options

A. The rate of absorption of digested food molecules would be higher, because the digested food would pass more easily thorugh the digestive tract.
B. Digestion would not be as effective, because there would be fewer cells scretting trypsin (a protein-digesting enzyme).
C. Humans would have needed to evolve a much longer small intesntine to absorb sufficient nutrients from their food.
D. Humans would not be able to survive, because the digestive tract would be more susceptible to damage.

Answer

C

Explanation

The absorptive surface of small intestinal mucosa have folds, which increase its surface area Also located on epithelial surface of small intestine are millions of small villi. Intestinal epithelial cell on each villus is characterised by a brush border which further increaes the surface area. Thus, to compensate for this and to have effective absorption of nutreints. intestine would need to be much-much longer in length