raws their foot","location":"specification"}]},{"type":"text","order":2,"title":"Link speed to protection","content":"The leg muscles contract and pull the foot away immediately. This makes contact with the spine shorter and reduces the chance that it penetrates more deeply.\n\nTherefore, the rapid reflex limits tissue damage to the foot. This clear link between quick withdrawal and less damage earns the second mark.","highlights":[{"text":"sharp sea urchin spine","location":"specification"}]}]}],"generatedAt":"2026-07-22T08:17:13.598Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"81a962cd-dbe8-4c52-b5b0-d9a36d9126ec","revisionId":"dde7dcf5-c062-48da-8923-7a8910e5ab2f","questionNumber":null,"questionType":"LA","specification":"A student accidentally touches a hot beaker of boiling water during a chemistry experiment. This triggers a rapid, automatic reflex action to pull their hand away.\n\n![A diagram of a reflex arc involved in a withdrawal reflex of the hand.](https://assets.mathsgenie.co.uk/aqa-qb/91303704-c66e-4926-8c3c-e1bde2c681c7.png)","difficulty":4,"difficultyBand":"medium","totalMarks":8,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"215a1cae-4b9f-494d-b501-290fb2dca21b","label":null,"content":"Describe the pathway of the nerve impulses from the temperature/pain receptors in the finger to the bicep muscle.\n\nIn your answer, you should:\n* name neurones $X$, $Y$, and $Z$\n* describe the sequence of events along the reflex arc, including how information is transmitted between neurones.","markscheme":"- Identifies **Neurone X** as the sensory neurone, **Neurone Y** as the relay neurone, and **Neurone Z** as the motor neurone B1\n- Describes that the heat/pain stimulus is detected by receptor(s) in the finger, generating an electrical impulse M1\n- Explains that the impulse travels along Neurone X (sensory neurone) to the spinal cord / central nervous system (CNS) M1\n- Explains that when the impulse reaches the end of Neurone X, chemical neurotransmitters are released M1\n- Describes how neurotransmitters diffuse across the synapse (gap) to trigger a new impulse in Neurone Y (relay neurone) M1\n- Explains that the impulse travels along Neurone Y and crosses a second synapse to Neurone Z (motor neurone) M1\n- Describes that the impulse travels along Neurone Z to the effector / bicep muscle M1\n- States that the bicep muscle (effector) contracts, pulling the hand away A1","marks":8,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"trace_reflex_arc","label":"Trace the reflex arc","steps":[{"type":"text","order":0,"title":"Name the neurones","content":"First use the arrows in the supplied diagram. **X** carries impulses from the finger *to* the spinal cord, so it is the **sensory neurone**. **Y** is entirely within the spinal cord, so it is the **relay neurone**. **Z** carries impulses from the spinal cord *to* the bicep, so it is the **motor neurone**.\n\nNaming all three correctly earns **B1**.","highlights":[{"text":"name neurones $X$, $Y$, and $Z$","location":"specification"}]},{"type":"text","order":1,"title":"Detect the stimulus","content":"Heat/pain from the hot beaker is the stimulus. Temperature/pain receptors in the finger detect it and generate an electrical impulse.\n\nThis earns **M1** for identifying the stimulus, receptors and electrical impulse.","highlights":[{"text":"temperature/pain receptors in the finger","location":"specification"}]},{"type":"text","order":2,"title":"Follow neurone X","content":"The electrical impulse travels along **neurone X**, the sensory neurone, into the spinal cord, which is part of the **central nervous system (CNS)**. This earns **M1**.","highlights":[{"text":"from the temperature/pain receptors in the finger to the bicep muscle","location":"specification"}]},{"type":"text","order":3,"title":"Release neurotransmitter","cont

The brain and the nervous system

Question 12

The brain and the nervous system Questions

The brain and the nervous system

Question 12

The brain and the nervous system Questions