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

The blood of a cockroach does not contain hemoglobin. This is because........

Which of the following statement$(s)$ is/are correct regarding the respiratory system of a cockroach?
$(i)$ It consists of a network of trachea that open through $12$ pairs of small holes called spiracles present on the lateral side of the body.
$(ii)$ Thin branching tubes carry oxygen from the air to all the parts.
$(iii)$ The opening of the spiracles is regulated by sphincters.
$(iv)$ Exchange of gases takes place at the tracheoles by diffusion.

The figure given below shows the reproductive system of a female cockroach. The correct labellings indicated by alphabets $(A, B, C)$ are respectively:

Identify $X, Y$ and $Z$ in the given figure of the male reproductive system of a cockroach.

The body cavity in a cockroach is also known as ........