Q131 / 180 · NEET 2020 (Phase 1) · Zoology

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

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

Solution

NERVOUS SYSTEM:

The nervous system of the cockroach consists of a series of fused, segmentally arranged ganglia joined by paired longitudinal connectives on the ventral side.

Brain: It is present in the head. It is made up of a pair of supra oesophageal which is the present above esophagus. It supplies nerves to antennae and compound eyes. The sub-oesophageal ganglia are present below the esophagus. These ganglions are connected together by paired longitudinal connectives on the ventral side.

Double Ventral Nerve Cord: They arise from sub-oesophageal ganglia and run-up to the posterior end of the body. These nerve cords are connected with the help of 9 pairs of segmented ganglion three in the thorax and 6 in the abdominal segment.

The nervous system of cockroaches is spread throughout the body. The head holds a bit of the nervous system while the rest is situated along the ventral side of the body.

Hence, the correct answer is option: 'B'.

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