In one type of neurological disease, neurons are unable to detect a certain stimulus which would normally cause pain. In a patient with this disease, which of the following would be true?
1 The patient would not show a reflex action to the stimulus.
2 The patient would be able to take appropriate action if they could also see the application of the stimulus.
3 The patient would be able to sense pain but would not be able to respond to it.
4 The patient would be able to sense pain but would not be able to communicate this to the brain.

Answer:

9) A

We need to know that neurones that detect a certain stimulus are called sensory neurones.

1 – Sensory neurones are the neurones that detect stimulus first in a reflex action. If sensory neurones are unable to detect a certain stimulus, then there will be no reflex action to the stimulus. So 1 is correct.

2 – If the patient can see that the stimulus is taking place and they know it will cause harm to the body, they can then take appropriate action to stop the application of the stimulus.

3 – The patient would not be able to sense pain as the neurones are unable to sense the pain.

4 – Again, they will not be able to sense the pain.

Only statements 1 and 2 are correct, meaning that option A is correct.