$(a)$ Why is there a difference in the rate of breathing between aquatic organisms and terrestrial organisms? Explain.
$(b)$ Draw a diagram of the human respiratory system and label the pharynx, trachea, lungs, diaphragm, and alveolar sac on it.

(N/A) Aquatic organisms breathe faster than terrestrial organisms because the amount of dissolved $O_2$ in water is much lower than the amount of $O_2$ in the atmosphere. To obtain sufficient $O_2$ for respiration, aquatic organisms must process a larger volume of water, leading to a higher rate of breathing.
$(b)$ Refer to the provided diagram for the human respiratory system.