Question

The functional respiratory organ of a fully formed Tadpole is the:
a. Skin
b. Lung
c. Gills
d. Air bladder

Answer 1

Tadpoles hatch from frog’s eggs and can only survive in water. They undergo metamorphosis to become adult frogs which respire from different organs, but as tadpoles they use gills for their respiration.

Complete answer:
When the frogs undergo metamorphosis they change in many ways. The adult and the immature, both forms need to take up oxygen from their environment, also the way they respire changes along with their maturation. Tadpoles use gills, while the mature frogs use three types of respiration.
Tadpoles have small external gill flaps that extract the dissolved oxygen from the water. The gills have very thin membranes which take up the oxygen from water where it enters the bloodstream with the help of diffusion. As the tadpoles mature the gills are replaced by other efficient respiratory systems.

Additional information: In mature frogs the respiration is cutaneous, it takes place through skin. The carbon dioxide is exhaled through the skin and oxygen is absorbed. You may have observed that their skin is very moist; this is due to mucus across the skin for better absorption through the body. Respiration also occurs through the lining of the mouth. This takes place only when the frog is not submerged in water. Other respiration is pulmonary respiration i.e. breathing through lungs as humans do. Despite this fact, their lungs are comparatively underdeveloped as they are not frequently used.

Note: Skin, lungs and gills are present in frogs for the purpose of respiration but the air bladder is present in fishes, particularly in bony fishes. Air bladder helps the fishes to swim as it creates buoyancy in them.