Q1. [3] straightforward initial-understanding
Describe the journey of a nerve impulse from a receptor to an effector (muscle or gland). Name the types of neurons involved at each stage.
Generated by claude-sonnet-4-6 · 2026-06-26 00:59 · grounding rag
Model Answer
Journey of a nerve impulse from receptor to effector:
- Receptor detects a stimulus; the dendritic tip of a sensory (afferent) neuron generates an electrical impulse.
- The impulse travels along the dendrite → cell body → axon of the sensory neuron to the spinal cord/brain.
- Here, an interneuron (relay/association neuron) processes and relays the impulse.
- The impulse is then carried by a motor (efferent) neuron to the effector (muscle or gland).
- At each junction, chemicals cross the synapse to continue the impulse. At the neuromuscular junction, the impulse causes the muscle to contract or the gland to secrete.
Source: Chapter 6, Section 6.1 – Animals: Nervous System
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Explanation
- Examiners expect three neuron types named correctly: sensory, relay/interneuron, motor.
- The pathway must be in sequence: receptor → sensory neuron → interneuron → motor neuron → effector.
- Mention synapse as the chemical bridge between neurons — it is a key term.
- For 3 marks, one mark each is typically awarded for: (i) correct pathway/sequence, (ii) naming the three neurons, (iii) role of synapse and effector response.