Describe sense organs as groups of receptor cells
Connect specialised detecting cells with particular kinds of stimulus.
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 receptors, electrical impulses, CNS organisation and the distinction between a stimulus and an effector response.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which is the detecting part of a sensory pathway?
What you will learn
- A sense organ includes receptor cells
- Detection is distinct from the response
Describe sense organs as groups of receptor cells
Sense organs include groups of specialised receptor cells. Detection, communication and effector response are distinct stages. Original teaching model.
| Feature | Meaning |
|---|---|
| Organisation | Groups of receptor cells within a sense organ |
| Input | Specific kind of stimulus |
| Communication | Electrical impulses towards CNS |
| Output | Separate effector response |
A sense organ includes receptor cells
A sense organ includes groups of receptor cells that respond to specific stimuli. The eye responds to light, while other sensory arrangements detect sound, touch, temperature or chemicals. Specific means that the receptor cells are suited to a particular kind of input, rather than every receptor responding equally to every change around the body.
The receptor cells provide the detecting part of the sensory pathway. Information can then be communicated by electrical impulses towards the central nervous system. Detection is not itself the final muscle or gland response: an effector acts after information has been processed through an appropriate pathway. The eye therefore does not need to become the moving muscle in order to detect a light stimulus.
Detection is distinct from the response
An organ includes several tissues and supporting structures as well as its receptor cells. The whole eye is not one light receptor, and the cornea, lens and optic nerve do not all carry out the same detecting function. Light-sensitive cells in the retina contribute to detection, while optical structures direct light and neural connections carry information onwards.
Use the level of organisation in the question. If asked to describe a sense organ, include groups of receptor cells and their specific stimulus. If asked to trace a response, add communication and effectors separately. A list of organ names alone does not explain what the receptors detect, while a description of movement alone omits the sensory input.
Sources for this lesson
Pause and explain
Which description includes the required organisation and response?
Worked example
Describe a sense organ and give its relation to a stimulus.
Show the worked solution
- Include a group of receptor cells.
- State that those cells respond to a specific kind of stimulus.
Answer A sense organ includes groups of receptor cells responding to specific stimuli.
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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.
Describe a sense organ in terms of cells and stimulus.
Give me a hint
Name organisation and specificity.
Compare my reasoning
- It includes groups of receptor cells.
- These respond to specific kinds of stimulus.
A sense organ includes groups of receptor cells responding to specific stimuli.
Look for these in your work
- Name receptor-cell groups
- State specific stimuli
Correct: the whole eye is one receptor cell.
Give me a hint
An organ and a cell are different organisation levels.
Compare my reasoning
- The eye contains multiple tissues and structures.
- Groups of receptor cells are found in its retina.
The eye is an organ containing several structures and groups of retinal receptor cells; it is not one receptor cell.
Look for these in your work
- Separate organ and cell
- Locate receptor-cell groups
A detected change leads to muscle contraction. Separate the receptor and effector roles.
Give me a hint
Detection precedes communication and action.
Compare my reasoning
- Receptor cells detect the stimulus.
- Muscle is an effector that contracts in the response.
Receptor cells detect the stimulus; neural communication links the input with a muscle effector whose contraction is the response.
Look for these in your work
- Separate detection and action
- Name the muscle effector
Common mistakes
- Calling a whole organ one receptor cell.
- Replacing detection with the final effector action.
What can you explain now?
Which description includes the required organisation and response?
Compare with the explanation
Groups of receptor cells responding to specific stimuli
It names both the cells and their input.
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Make it stick
Describe a sense organ using groups of receptor cells and stimulus specificity.
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.