Question

question 20 of 25
a student made a model of a lung using a straw, some modeling clay, and a glass bottle. first the student inserted the straw into the opening of the bottle. then the student sealed the connection by pressing modeling clay around the straw at the bottles opening.
one limitation of the model is that it does not represent how a lung can expand and contract as it fills with air. which way of refining the model would best address this limitation?
a. filling the bottle with small glass beads instead of air
b. using glue instead of modeling clay to seal the opening
c. using a flexible straw that bends instead of a rigid straw
d. using a flexible container such as a balloon instead of the glass bottle
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Explanation:

The key is to find a material that can expand and contract like a lung. A glass bottle is rigid and can't do this. A balloon is flexible and can expand and contract as air enters or leaves, better mimicking lung function.

Answer:

D. Using a flexible container such as a balloon instead of the glass bottle