Which animal has unpaired lungs?

Which function is served by the tracheal system in insects?

With respect to the respiratory apparatus,pick out the incorrect pair/pairs.

Submerged hydrophytes exchange gases through

Choose the correct option by matching the organisms in Column-$I$ with their respective respiratory organs in Column-$II$.

Column-$I$	Column-$II$
$(p)$ Sponges	$(I)$ Through tracheal tubes
$(q)$ Insects	$(II)$ Through lungs
$(r)$ Molluscs	$(III)$ Vascularized gills
$(s)$ Reptiles	$(IV)$ Simple diffusion over their entire body surface
	$(V)$ By their moist cuticle

Find the correct sequence for $p-q-r-s$.

Which of the following is not a character of a respiratory surface?