OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What is the primary reason for the length of neurons in the nervous system?

1. They are long which speeds up the impulse

2. They contain more neurotransmitters

3. They have a larger surface area for connections

4. They are less likely to sustain damage

The correct answer is: They are long which speeds up the impulse

The primary reason for the length of neurons in the nervous system is that they are long, which speeds up the impulse. The elongated structure of neurons allows them to transmit electrical signals more efficiently over significant distances. This is particularly important in the nervous system, where information must be relayed quickly between various parts of the body. The length of the neuron enables the propagation of action potentials along the axon, particularly in myelinated neurons, where the myelin sheath facilitates faster transmission through saltatory conduction. This capability is crucial for rapid reflexes and coordination of bodily functions, ensuring that responses to stimuli are prompt and effective. Regarding the other options, they do not address the fundamental role of neuron length in impulse transmission as effectively. While neurotransmitter presence and connection surface area are important for communication and synaptic strength, they do not specifically explain why the physical length of the neuron itself contributes to faster signal transmission. Similarly, while neuron structural integrity is important, length primarily pertains to the speed of the nerve impulse rather than damage resistance.