The small intestine forms from which germ layer?
a) I only
b) II only
c) III only
d) I and II
As a guideline for the MCAT, the ectoderm forms outer coverings of body, e.g. skin/hair/nails, and the nervous system. The endoderm forms the lining of the digestive tract and most of the liver and pancreas. Mesoderm forms everything in-between, e.g. muscle, bone, circulatory system, heart, spleen, gonads.
a) I only, correct.
b) II only, incorrect, The mesoderm forms the tissues between the body’s outer coverings and the lining of the digestive tract.
c) III only, incorrect, The ectoderm forms the body’s outer coverings and nervous system.
d) I and II, incorrect, On the MCAT, organs and tissues will derive from one layer only.