Exhalation is the process of expulsion of air through the respiratory tract. Which of the following figures illustrates the process of exhalation?

What is the most important function of the diaphragm in mammals?

Expiration occurs only when.....

Which of the following statements is correct about the mechanism of breathing?

Given below are events occurring during inspiration. Select the correct order of sequence from the options given below.
$(I)$ Air from atmosphere rushes into lungs.
$(II)$ Thoracic volume increases.
$(III)$ Intercostal muscles contract and ribs along with sternum move upward and outward.
$(IV)$ Diaphragm becomes flat and goes downwards.

Sugar is converted into starch when the $pH$ of guard cells increases,which is associated with: