Q. Sponges exchange O₂ with CO₂ by ____.
A) gills
B) simple diffusion over their entire body surfaces
C) moist cuticle
D) tracheal tubes
Explanation
[Solution from source] Sponges have no respiratory organs; water flowing through the canal system lets O₂ and CO₂ diffuse across the body surface. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.