Question

If the head of a cockroach is removed, it may be alive for few days because:

• A. The head holds a small proportion of a nervous system while the rest is situated along the ventral part of its body
• B. The head holds a ${\frac{1}{3}}^{rd}$ of the nervous system while the rest is situated along the dorsal part of its body
• C. The supra-oesophageal ganglia of the cockroach are situated in the ventral part of abdomen
• D. The cockroach does not have nervous system

Answer 1

The correct option is A The head holds a small proportion of a nervous system while the rest is situated along the ventral part of its body

The nervous system in cockroaches is dispersed throughout the body. It is constituted by a series of fused ganglia. These are segmentally arranged and ventrally joined by paired longitudinal connectives. The head contains the supra-oesophageal ganglia which represents the brain. It supplies nerves to antennae and compound eyes.
Hence, the head region holds a small part of the nervous system while the majority of it is situated in the belly side (ventral part) of the body. Thus, a cockroach can survive for a few days even if it loses its head.