AP BIOLOGY

Detailed explanation-1: -During exhalation, ribs move down and inwards, while diaphragm moves upwards and relaxes. This reduces the size of the chest cavity and the air is expelled out of the lungs through a process called exhalation.

Detailed explanation-2: -The intercostal muscles get relaxed. Carbon dioxide is pushed out from the lungs, windpipe, and nose. As the muscles get relaxed, they move their rib cage downwards and inwards. Therefore the ribs move downward at the time of exhalation.

Detailed explanation-3: -As they relax they position rib cage downwards and inwards. As the space in the chest cavity gets smaller, the air rich in carbon dioxide is forced out of your lungs and windpipe, and then out of your nose or mouth. Hence During exhalation, the ribs move downwards. So, the correct answer is ‘Move downwards’.

Detailed explanation-4: -When the lungs inhale, the diaphragm contracts and pulls downward. At the same time, the muscles between the ribs contract and pull upward.

Detailed explanation-5: -During normal breathing, contraction of the major inspiratory muscle, the diaphragm, produces both rib cage expansion and a downward movement of the diaphragm.