Question

which of the following best describes what alveoli are?
a. they are the smallest tubes in the respiratory system.
b. they have a small amount of surface area.
c. they are found on the end of bronchioles.
d. they are comprised of millions of cells.

please select the best answer from the choices provided.

○ a
○ b
○ c
○ d

Explanation:

To solve this, we analyze each option:

• Option A: The smallest tubes in the respiratory system are bronchioles, not alveoli. Alveoli are tiny sacs, so A is incorrect.
• Option B: Alveoli have a large surface area (due to their numerous, small, and folded structures) to facilitate gas exchange, so B (saying small surface area) is wrong.
• Option C: Alveoli are indeed found at the end of bronchioles. Bronchioles branch into alveolar ducts and then alveoli, so this description is correct.
• Option D: Alveoli are made up of a single layer of cells (type I pneumocytes) for efficient gas exchange, not millions of cells. So D is incorrect.

Answer:

C. They are found on the end of bronchioles.