Describe a synapse as a junction between neurones
Separate the whole junction from the small gap within it.
Exam scope and assessment notes
Mapped to the named 0973 section using teaching from the corresponding single-science course. A 0973-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade. This qualification reports two grades on the 9–1 scale; confirm the entry route for your zone and exam series.
Before you begin
- Recall cell membranes, diffusion, sensitivity and the difference between cells, tissues and organs.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
How many separate neurones are named in the required synapse definition?
What you will learn
- Neurones meet at specialised junctions
- The gap is one part of the synapse
Describe a synapse as a junction between neurones
A synapse is a junction between two neurones. In the chemical model the gap is one part of the whole specialised junction, not its entire definition. Original teaching model.
| Feature | Meaning |
|---|---|
| Participating cells | Two separate neurones |
| Connection | Synaptic junction |
| Gap | Space between cell regions in the chemical model |
| Interpretation | A connecting line does not mean cell fusion |
Neurones meet at specialised junctions
A synapse is a junction between two neurones in the required Core account. It connects communication from one nerve cell with the next in a pathway. The neurones remain separate cells rather than becoming one continuous cell simply because information can pass between them.
In the chemical-synapse model developed in Supplement teaching, the terminal of the first neurone is separated from the next cell by a synaptic gap. The entire junction includes the adjoining specialised cell regions as well as that gap. Synapse should therefore not be defined only as an empty space with no participating cells.
The gap is one part of the synapse
A simple reflex arc includes junctions between its sensory, relay and motor communicating cells. These links allow input to be integrated with output in the supplied pathway. A motor connection to a muscle is a related specialised junction, but this numbered Core requirement specifically asks for a junction between two neurones.
Electrical impulses travel along neurones, while a chemical junction uses neurotransmitter release, diffusion and binding in the Extended account. The Core definition does not require every intermediate mechanism, but it should preserve the two-cell junction idea. A drawn line linking two neurones summarises communication rather than proving their cell membranes are fused into one uninterrupted tube.
Sources for this lesson
Pause and explain
Which is the required definition?
Worked example
Define a synapse in the required Core account.
Show the worked solution
- Name the junction.
- Specify the two participating nerve cells.
Answer A synapse is a junction between two neurones.
Try a topic test
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Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
State the required Core definition of a synapse.
Give me a hint
Use junction and two neurones.
Compare my reasoning
- It is a communication junction.
- The participating cells are two neurones.
A synapse is a junction between two neurones.
Look for these in your work
- Name a junction
- Name two neurones
Distinguish the synaptic gap from the whole chemical synapse.
Give me a hint
The junction also includes specialised parts of the two cells.
Compare my reasoning
- The gap is the space between them.
- The synapse includes the whole specialised junction.
The synaptic gap is one part of the chemical synapse; the whole junction also involves specialised regions of the two separate neurones.
Look for these in your work
- Separate gap and junction
- Retain the two cells
A drawing links two neurones with a line. Does this establish that they have fused into one cell?
Give me a hint
A connection can summarise transmission without fusion.
Compare my reasoning
- The neurones remain separate.
- A synapse links their communication.
No. The line summarises a synaptic connection between separate neurones; it does not establish cell fusion.
Look for these in your work
- Recognise schematic meaning
- Keep the two cells separate
Common mistakes
- Defining the whole synapse only as empty space.
- Saying the two neurones fuse into one cell.
What can you explain now?
Which is the required definition?
Compare with the explanation
Junction between two neurones
It preserves the cell-to-cell connection.
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Make it stick
Define a synapse and distinguish the gap from the complete junction.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.