Biology · Structural Organisation in Animals · NEET
This is the most tested point. IN WATER: the frog breathes only through its moist skin (cutaneous respiration) because gases dissolve in water and pass through the wet, richly vascular skin. It does NOT use its lungs or buccal cavity under water. ON LAND: all three surfaces work together, the skin, the buccal (mouth) cavity lining, and the lungs. So water = 1 surface (skin), land = 3 surfaces (skin + buccal + lungs).
1) Skin, called cutaneous respiration. 2) Buccal cavity lining, called buccopharyngeal respiration. 3) Lungs, called pulmonary respiration. For NEET remember both the organ and its formal term, because match-the-column questions can ask for the name (cutaneous = skin).
The skin is moist and highly vascular (has many blood capillaries just under the surface). Oxygen dissolves in the thin film of moisture, diffuses through the thin skin, and enters the capillaries; carbon dioxide leaves the same way. If the skin dries, this exchange stops, which is why frogs must stay moist.
Lungs are a pair of elastic, thin-walled, highly vascular sac-like structures present in the thoracic region. Air is drawn in through the nostrils into the buccal cavity, and from there pushed into the lungs by buccal-cavity movements (a buccal force-pump, not a diaphragm like in humans). This is called pulmonary respiration.
No. Buccopharyngeal respiration is gas exchange across the moist lining of the buccal (mouth) cavity itself. Pulmonary respiration is gas exchange inside the lungs. They are different surfaces. On land both operate; the buccal cavity also helps pump air into the lungs, but the gas exchange across its own lining is counted separately.
Frogs respire in water by skin and buccal cavity and on land by skin, buccal cavity and lungs. Choose the correct answer from the following:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Skin (cutaneous respiration), the buccal cavity lining (buccopharyngeal respiration) and lungs (pulmonary respiration).
Only through its moist, vascular skin by cutaneous respiration. It does not use its lungs or buccal cavity in water.
Gas exchange through the moist, richly vascular skin. Oxygen dissolves in the moisture and diffuses into the skin capillaries; carbon dioxide passes out the same way.
No. A frog has no diaphragm. Air is pushed into the lungs by movements of the buccal cavity acting as a force-pump.
Because skin respiration needs a wet surface for gases to dissolve and diffuse. If the skin dries, cutaneous gas exchange stops.
