","$L3f",null,{"backHref":"/gcse/biology/edexcel/questions","basePath":"/gcse/biology/edexcel/the-brain-and-the-nervous-system/questions","formulaUrl":null,"initialIndex":53,"initialQuestionWindow":[{"id":"ac05f5c4-60ec-4d27-9921-1a17ad6c32f3","revisionId":"50229d16-a7de-4d05-ba46-f32f671b3bbe","questionNumber":null,"questionType":"LA","specification":"A clinical research team is developing a therapeutic strategy for a patient who has suffered a traumatic injury to the spinal cord and a localized lesion in the cerebral cortex.","difficulty":4,"difficultyBand":"medium","totalMarks":2,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"3568932f-c770-4179-91f1-6b23452c867a","label":null,"content":"Explain two biological or physical reasons why treating injuries to the central nervous system (CNS) presents greater challenges to medical professionals than treating injuries to other organ systems.","markscheme":"- Explains a cellular or structural limitation, such as neurones in the CNS being unable to easily regenerate or repair themselves, or the delicate and complex nature of the tissue making surgery highly risky. B1\n- Explains a physical or physiological barrier, such as the skull or vertebral column making physical access difficult, or the blood-brain barrier preventing therapeutic drugs from entering the CNS tissue. B1","marks":2,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"cns_challenges","label":"Explain two CNS challenges","steps":[{"type":"text","order":2,"title":"Explain limited repair","content":"Choose a distinct biological reason: neurones in the CNS do not easily regenerate (regrow) or repair themselves after injury. Therefore, damaged spinal-cord or brain tissue is difficult to restore, making treatment more challenging.\n\nThis is one explained biological reason, so it earns **B1**.","highlights":[{"text":"traumatic injury to the spinal cord and a localized lesion in the cerebral cortex","location":"specification"}]},{"type":"text","order":3,"title":"Explain difficult access","content":"For a different reason, physical access to the CNS is difficult: the skull surrounds the brain and the vertebral column surrounds the spinal cord. Reaching the damaged tissue may therefore require risky surgery and can cause further damage.\n\nThis is a distinct physical reason, so it earns the second **B1**.","highlights":[{"text":"traumatic injury to the spinal cord and a localized lesion in the cerebral cortex","location":"specification"}]}]}],"generatedAt":"2026-07-22T08:53:25.855Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"b40bd397-98a5-445b-b6ef-68655f7aa7df","revisionId":"f3d11828-303a-477e-a304-d28ef314aef3","questionNumber":null,"questionType":"LA","specification":"The diagram shows the synaptic junction between a sensory neurone and a relay neurone in a spinal reflex arc.\n\n![Synapse diagram](https://assets.mathsgenie.co.uk/aqa-qb/afb2cde7-6ff7-4490-8c2c-7d47a8602c54.png)","difficulty":4,"difficultyBand":"medium","totalMarks":4,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"d1e50ba6-2dbc-4148-88a1-80ac8e52ecc6","label":null,"content":"Describe the sequence of events by which an electrical impulse is transmitted from the sensory neurone to the relay neurone across this synapse.","markscheme":"- The arrival of an electrical impulse (action potential) at the axon terminal of the sensory neurone triggers the release of neurotransmitter chemicals from synaptic vesicles into the synaptic cleft B1\n- These neurotransmitter molecules diffuse across the synaptic cleft (down a concentration gradient) B1\n- The neurotransmitters bind to specific, complementary receptor proteins on the post-synaptic membrane of the relay neurone B1\n- This binding opens ion channels, triggering a new electrical impulse (action potential) in the relay neurone B1","marks":4,"order":0,"markingRubric":null,"explanation

The brain and the nervous system

Question 19

The brain and the nervous system Questions

The brain and the nervous system

Question 19

The brain and the nervous system Questions