What respiratory structure delivers oxygen directly to tissues in insects?

What respiratory structure delivers oxygen directly to tissues in insects?

• A. Spiracles
• B. Gills
• C. Tracheae
• D. Air sacs

Answer: (C)

Insects breathe through a branched tracheal system. Air enters through spiracles, travels down the tracheae, and then reaches the finest tubes called tracheoles that come into close contact with every tissue. Oxygen diffuses from these tracheoles directly into cells, meeting their metabolic needs. Gills are used by some aquatic insects, and air sacs mainly help move and store air, but they don’t deliver oxygen to tissues as directly as the tracheal network does. So the structure that delivers oxygen directly to tissues is the tracheae (as part of the tracheal system, culminating in the tracheoles).

Insects breathe through a branched tracheal system. Air enters through spiracles, travels down the tracheae, and then reaches the finest tubes called tracheoles that come into close contact with every tissue. Oxygen diffuses from these tracheoles directly into cells, meeting their metabolic needs. Gills are used by some aquatic insects, and air sacs mainly help move and store air, but they don’t deliver oxygen to tissues as directly as the tracheal network does. So the structure that delivers oxygen directly to tissues is the tracheae (as part of the tracheal system, culminating in the tracheoles).