Section: Biological and Biochemical Foundations of Living Systems

13) The lining of the digestive tract and the respiratory tract develops from which germ layer? I. Endoderm II. Mesoderm III. Ectoderm

1. I only
2. II only
3. III only
4. I and II

The lining of the digestive tract and the respiratory tract develops from the endoderm. As a rule of thumb for the MCAT, think of the fetus developing from a tube. Skin and nervous systems develop from ectoderm (outside of tube), digestive tract and respiratory tract from endoderm (inside of tube), and cardiovascular, skeletal, and muscle tissues develop from mesoderm (in-between outside and inside of tube). On MCAT questions, tissues will almost always develop from one germ-layer only. I. Endoderm II. Mesoderm III. Ectoderm