Which of the following is absent in the mouthparts of a housefly?

In cockroach,which of the following is the principal motor centre?

In cockroaches,during the digestion of food,the enzyme cellulase is synthesized by:

Blood does not transport oxygen in

Which one of the following is one of the paths followed by air or $O_2$ during respiration in the adult male $Periplaneta$ $americana$ as it enters the animal body?

The heart of a cockroach is........