Question

Which one feature is common in leech, cockroach, and scorpion?
a) Nephridia
b) Ventral nerve cord
c) Cephalization
d) Antennae

Answer 1

Ventral nerve cord is common in leech, cockroach, and scorpion. It is a tissue that runs the length of the animal in the lower part of its body. The ventral nerve cord is generated in the embryo at a very early stage. In insects, the ventral nerve cord consists of a subesophageal ganglion in the head and connected to the brain by circumesophageal connectivities.

Complete answer: 1)Ventral nerve cords are found particularly within the vertebrates. They are well-studied within insects, and VNCs have been found in over 300 species covering all the major orders.
2)The VNC contains ascending and descending neurons that send and receive information to and from the brain.
3)Motor neurons that project into the body and onto the muscles, sensory neurons that receive information from the body and surrounding environment.
4)And then the reflexes perform their task by physical movement of the body.
Thus, the correct answer is option(B).Ventral nerve cord

Additional information:
In an insect body, the ventral nerve cords are developed on the basis of the body plan, a segmental set of 30 paired and one unpaired neuroblast. A neuroblast can be identified on the basis of its position in the array. Its pattern of molecular expression, and the suite of early neurons that it produces. Each neuroblast gives rise to two hemilineages: an "A" hemilineage and a "B" hemilineage.

Note: The VNC coordinates neural signaling from the brain to the body and vice versa, connecting sensory input and locomotor output. Decapitated insects can still walk, groom, and mate, illustrating that the circuitry of the VNC is sufficient to perform complex motor programs without brain input.