Which of these is a respiratory organ in mammals?

1. Analyze the question The question asks for the respiratory organ in mammals, meaning the organ where gaseous exchange takes place (oxygen goes into the blood, carbon dioxide comes out).

2. Explain the concept Respiration involves taking in oxygen and removing carbon dioxide. Different animals use different organs for this:

• Fish: gills
• Insects: tracheae (spiracles and tracheal tubes)
• Amphibians: skin, lungs, and buccal cavity (mouth)
• Mammals: lungs

Mammals, including humans, have lungs with millions of tiny air sacs called alveoli. These have thin, moist walls and a rich blood supply, which makes gaseous exchange efficient.

3. Go through the options

• A. Skin: It is a respiratory surface in amphibians such as frogs, but not in mammals. In mammals it protects the body, regulates temperature, and senses touch.
• B. Mouth: Air passes through it, but no gaseous exchange takes place there. It is mainly for feeding and an alternative air passage.
• C. Heart: It pumps blood around the body. It is a circulatory organ, not a respiratory one.
• D. Lungs: Gaseous exchange takes place in the alveoli of the lungs. This is correct.

4. Answer The correct option is D. lungs.

5. Exam tip Match the animal to its respiratory organ. A simple memory aid is "Fish-Gills, Insect-Tracheae, Mammal-Lungs, Frog-Skin." In JAMB, watch for distractors like the skin, which is a true respiratory surface in some animals but not in mammals.