Question

The image shows different stages of pulmonary respiration in a frog. Choose the correct order of its occurence from inspiration to expiration.

• A. 1, 2, 3, 4
• B. 2, 1, 3, 4
• C. 3, 2, 4, 1
• D. 4, 3, 2, 1

Answer 1

The correct option is A 1, 2, 3, 4

Inspiration (Images 1 & 2)
1- The frog lowers the floor of its mouth which causes the throat to expand. Then the nostrils open allowing air to enter the enlarged mouth.
2- The nostrils then close and the air in the mouth is forced into the lungs by contraction of the floor of the mouth.
Expiration (Images 3 & 4)
3- To eliminate the carbon dioxide in the lungs the floor of the mouth moves down, drawing the air out of the lungs and into the mouth.
4- Finally the nostrils open and the floor of the mouth is moved up pushing the air out of the nostrils.