Which of the following is NOT a component of a reflex arc?

• A. Motor neuron
• B. Sensory receptor
• C. Effector organ
• D. Red blood cell

Answer: (D)

Verified step by step guidance

1. Step 1: Begin by understanding the concept of a reflex arc. A reflex arc is the neural pathway that controls a reflex action. It typically involves five main components: sensory receptor, sensory neuron, integration center, motor neuron, and effector organ.
2. Step 2: Analyze each option provided in the question. The components listed (motor neuron, sensory receptor, effector organ) are all part of the reflex arc. A motor neuron transmits signals from the central nervous system to the effector organ, a sensory receptor detects stimuli, and the effector organ carries out the response.
3. Step 3: Consider the role of red blood cells in the body. Red blood cells are responsible for transporting oxygen and carbon dioxide in the bloodstream, but they are not involved in the neural pathway of a reflex arc.
4. Step 4: Compare the function of red blood cells to the components of a reflex arc. Since red blood cells do not play a role in detecting stimuli, transmitting signals, or responding to stimuli, they are not a component of a reflex arc.
5. Step 5: Conclude that the correct answer is red blood cell, as it is not part of the reflex arc, unlike the other options provided.