Question

If the head of cockroach is removed, It may live for few days because:

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

Answer 1

The Correct Option is C

The question asks why a cockroach can survive for several days after its head is removed. To answer this, let’s evaluate each of the given options:

1. The supra-oesophageal ganglia of the cockroach are situated in the ventral part of the abdomen.

   This statement is incorrect. The supra-oesophageal ganglia, which form a part of the cockroach's nervous system, are located in the head, not the ventral part of the abdomen.

2. The cockroach does not have a nervous system.

   This statement is false. Cockroaches do have a nervous system; it is decentralized, which is why they can survive headless for a while.

3. The head holds a small proportion of a nervous system while the rest is situated along the ventral part of its body.

   This statement is correct. In cockroaches, a significant portion of the nervous system is located in the ventral nerve cord that runs through its body. The head contains only a small part of the cockroach's nervous system, which allows the insect to survive even if the head is removed.

4. The head holds a $1/3^{\text{rd}}$ of a nervous system while the rest is situated along the dorsal part of its body.

   This option is incorrect. While the head holds only a small part of the nervous system, the rest is located along the ventral, not the dorsal, part of its body.

To conclude, the correct answer is that the head holds a small proportion of the nervous system while the rest is situated along the ventral part of the body. This characteristic of a decentralized nervous system allows the cockroach to continue living for days without its head.