Which of the following is not true w.r.t. nervous system of cockroach?

Options

A. It consists of a series of fused, segmentally arranged gangula present on ventral side of body
B. Nervous system of cockroach is spread throughout its body
C. Double ventral nerve cord consists of 9 gangula, 6 in thorax and 3 in abdomen
D. If the head of cockroach is cut off, it will still live for as long as one week

Answer

To determine which statement is not true regarding the nervous system of a cockroach, we will analyze each option provided in the question.

1. **Statement 1**: "It consists of a series of fused segmented ganglia connected or present on the ventral side of the body."
- This statement is true. The nervous system of the cockroach is indeed composed of a series of fused segmented ganglia that are located on the ventral side of its body.

2. **Statement 2**: "Nervous system of cockroach is spread throughout its body."
- This statement is also true. The nervous system of a cockroach is distributed throughout its body, allowing for various functions and responses.

3. **Statement 3**: "Double ventral nerve cord consists of 9 ganglia, 6 in thorax and 3 in abdomen."
- This statement is incorrect. The double ventral nerve cord of a cockroach actually consists of 3 pairs of ganglia in the thorax and 6 pairs in the abdomen, totaling 12 ganglia, not 9.

4. **Statement 4**: "If the head of the cockroach is cut off, it will still live for as long as one week."
- This statement is true. Cockroaches can survive for a week without their heads because their nervous system is decentralized and spread throughout their body.

Based on the analysis, the statement that is not true regarding the nervous system of the cockroach is **Statement 3**.