Which of the following is NOT required for a reflex arc?

Step 1: Define the Problem

Identify the components involved in a reflex arc and determine which one is not necessary.

Step 2: Break Down the Problem

1. List the typical components of a reflex arc.
2. Identify the component that is not essential for a reflex arc to function.

Step 3: Apply Relevant Concepts

A reflex arc generally includes the following components:

• Receptor: Detects the stimulus.
• Sensory Neuron: Transmits the signal to the central nervous system.
• Integration Center: Processes the information (usually in the spinal cord).
• Motor Neuron: Carries the signal away from the central nervous system.
• Effector: Produces a response (e.g., muscle or gland).

Step 4: Analysis, Verify and Summarize

Analyze each component's role in the reflex arc:

• The receptor is necessary to detect stimuli.
• The sensory neuron is required to transmit signals to the CNS.
• The integration center processes the signal.
• The motor neuron is needed to send signals to the effector.
• The effector is necessary to carry out the response.

Final Answer

The component that is NOT required for a reflex arc is the brain. Reflex arcs can function without involving the brain, as they often occur at the level of the spinal cord.