40. Circulatory System

Which best describes what happens during exhalation?

When you exhale, __________.

What is the main function of the respiratory system?

How do gases enter and exit the leaves of plants during gas exchange?

Which structure in plants serves as an opening for the exchange of gases and water?

In the alveoli and lung capillaries, carbon dioxide and oxygen are exchanged by means of __________.

When you hold your breath, which of the following blood gas changes leads initially to the urge to breathe again?

What happens when the CO₂ level from cellular respiration increases in the blood?

Countercurrent flow in the gills of a fish __________.

Which of the following components of the mammalian gas exchange system has a surface covered by a thin film of fluid without cilia?

What is the major reason that land-dwelling mammals evolved lungs rather than gills as a primary respiratory organ?

What is the correct order of structures through which air passes as it is inhaled by a typical mammal?

For a body surface to be a respiratory surface, it must __________.

Gas exchange in the gills of a bony fish is maximized by which of the following?