Question

Buccopharyngeal respiration in frog __________________.

• A. Is increased when nostrils are closed
• B. Stops when there is pulmonary respiration
• C. Is increased when it is catching fly
• D. Stops when mouth is opened

Answer 1

The correct option is D

Explanation of the correct answer:

1. Buccopharyngeal respiration occurs when the animal is on the land or partially immersed in water.
2. There are present two external nares situated at the tip of the snout.
3. Each external naris (nostril) leads into a nasal chamber which opens into the buccopharyngeal cavity by an internal naris.
4. During this mode of respiration, the mouth and glottis are tightly closed while the nares are kept open.
5. So, if the mouth opens buccopharyngeal respiration stops.

Explanation of the incorrect answers:

Option A:

1. The air inters through the external and internal nares (nostrils) into the buccopharyngeal cavity.
2. Therefore, it stops by the closure of the nares or mostrils.

Option B:

1. The buccopharyngeal respiration decreases when the frog tries to catch the fly, as the frog open up the mouth for feeding.
2. Hence, this option is incorrect.

Option C:

1. Pulmonary respiration is less frequent than the cutaneous and buccopharyngeal respiration.
2. It occurs when need for oxygen is increased.
3. Respiratory path includes external nares, nasal chambers, internal nares, buccopharyngeal cavity and glottis.
4. Therefore, as the air is passing by through the buccopharyngeal cavity also, hence, it does not completely stops during pulmonary respiration.

Final answer: Buccopharyngeal respiration in frog stops when mouth is opened.