Q BankQuestion BankDocsDocuments

C3.1.5—Spinal cord

Spinal cord links named stimuli, coordinating structures and effectors so body systems or plant tissues produce an integrated biological response.

Syllabus
First assessment 2025
Objective
C3.1.5
Level
SL

Exam analysis

Chance of appearing1%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper1B
Typical marks1

Common command terms

  • State

Recent exam appearances

May 2025Paper1B ["SL"] · TZ33(c)[ 1 ]C3.1.5—Spinal cord
Practice this objective

Coverage 2025–2025 · Updated 16 Jul 2026

The spinal cord can integrate a rapid response

The spinal cord can integrate a rapid response.

The spinal cord links body and brain, but grey matter can connect sensory input to motor output without waiting for conscious brain processing. White matter carries impulses along longer pathways.

receptor → sensory neurone → spinal integration → motor neurone → effector.

Touching a hot surface triggers a withdrawal through a spinal reflex; the brain receives information as the movement is already beginning.

A reflex is not brain-free information: the spinal cord handles the immediate response, while the brain can receive the signal afterwards.

Spinal cord

Assessment in practice

1 marks
How it is assessed

This objective is assessed through structured response, commonly using State.

Command terms

State

What earns marks

Mark schemes reward named structures, correct direction of information flow and explanations that keep the sequence causal.

Representative question

Question 1

[Maximum number: 1]

The spinal cord is involved in the coordination of involuntary actions such as the pain reflex.

Where are synapses between sensory neurons and interneurons found?

Body-System Integration

  • Nervous signals, hormones and blood transport integrate organs into coordinated systems; emergent functions arise from their interactions.
  • Sensory neurons carry receptor input to the CNS; motor neurons carry output to effectors. Mixed nerves contain both fibre types.
  • Reflex arcs provide rapid involuntary responses through sensory, relay and motor neurons. The spinal cord also links the brain and peripheral nerves.
  • Cerebral hemispheres support conscious processing; the cerebellum coordinates movement and balance; the medulla adjusts ventilation and heart activity.
  • The hypothalamus links nervous and endocrine control through the pituitary. Pineal melatonin helps time sleep; adrenal epinephrine supports acute stress responses.
  • Baroreceptors and chemoreceptors provide feedback about pressure, CO2, pH and O2.
  • The CNS controls voluntary swallowing and egestion, while the enteric nervous system coordinates gut peristalsis.

Concept essentials

  • Spinal cord depends on linking the stimulus to the coordinating structure or signal.
  • The pathway for spinal cord must keep information flow and response direction clear.
  • Named tissues, hormones, neurons or effectors give spinal cord its biological specificity.
  • Evidence about spinal cord is strongest when structure, mechanism and outcome are connected.
ConceptIB Biology SL