Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test

Which activity best models the function of the esophagus?

1. Transferring liquids between two containers

2. Squeezing a small greased ball through plastic tubing

3. Pumping air into a balloon

4. Pouring sand down a funnel

The correct answer is: Squeezing a small greased ball through plastic tubing

The activity that best models the function of the esophagus is the one that involves squeezing a small greased ball through plastic tubing. The esophagus is a muscular tube connecting the throat (pharynx) with the stomach that transports food through a process called peristalsis, which involves rhythmic contractions of its muscles to push food down toward the stomach. Squeezing the ball through the tubing demonstrates how the muscular contractions of the esophagus function to move substances from one point to another. The greased ball represents food that has been swallowed, and the plastic tubing simulates the esophagus as the passageway through which food travels. The other activities do not accurately reflect this function. Transferring liquids between two containers involves pouring without the directional, muscular movement characteristic of the esophagus. Pumping air into a balloon focuses on inflating an object rather than the movement of solids through a confined space. Pouring sand down a funnel demonstrates gravity and the free-fall of particles, which does not parallel the coordinated muscular action in the esophagus.