Which statement is true about respiration across the three groups?

Which statement is true about respiration across the three groups?

• A. Some use lungs and some use gills
• B. All use lungs
• C. All use gills
• D. None use lungs

Answer: (B)

The main idea here is that these three groups share lungs as their method of respiration. In mammals, birds, and reptiles, breathing involves drawing air into lungs where oxygen is exchanged for carbon dioxide. This adaptation lets them take in air from the surroundings directly, without needing water as the medium, unlike gills which extract oxygen from water and are found in fish and some aquatic life stages of amphibians. So, saying that all three use lungs correctly captures their common respiratory mechanism. The other statements would require some of the groups to rely on gills, or on no lungs at all, which isn’t the case for these three groups.

The main idea here is that these three groups share lungs as their method of respiration. In mammals, birds, and reptiles, breathing involves drawing air into lungs where oxygen is exchanged for carbon dioxide. This adaptation lets them take in air from the surroundings directly, without needing water as the medium, unlike gills which extract oxygen from water and are found in fish and some aquatic life stages of amphibians. So, saying that all three use lungs correctly captures their common respiratory mechanism. The other statements would require some of the groups to rely on gills, or on no lungs at all, which isn’t the case for these three groups.