Question

In the given diagram:

1. Name the parts labelled A, B, and C.
2. Write the functions of A and C.
3. Reflex arcs have evolved in animals? Why?

Answer 1

1. A: Sensory neuron or Nerve
   B.: Relay neuron or Interneuron
   C: Effector
2. The functions of A and C are as follows:
   A: The sensory neuron conducts the nerve impulses towards the Central Nervous System (CNS). The CNS is comprised of the brain and the spinal cord.
   C: The effector organ shows response by contracting or secreting a product.
3. Animals have evolved reflex arcs because the brain's reasoning process is too slow for them. Many animals lack the intricate neuronal network required for thought, or have relatively few of them. Reflex arcs have probably developed as an efficient means of surviving in the absence of actual cognitive processes. However, reflex arcs continue to be more effective for fast responses even after the development of complex neuron networks.