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The diagram shows a reflex arc in the human body - Edexcel - GCSE Biology - Question 5 - 2015 - Paper 1
Question 5
The diagram shows a reflex arc in the human body. (a) (i) Complete the sentence by putting a cross (✗) in the box next to your answer. Neurone X carries an impulse ... show full transcript
Worked Solution & Example Answer:The diagram shows a reflex arc in the human body - Edexcel - GCSE Biology - Question 5 - 2015 - Paper 1
Step 1
Step 2
Step 3
Explain the advantage of the reflex action that will occur when the pin pierces the skin of the finger.
Answer
The reflex action allows for a rapid response to harm, minimizing injury. Since this process bypasses the brain initially, it occurs quickly, helping the individual withdraw from the painful stimulus without delay.
Step 4
Describe how the brain is linked to the skin of the finger in this reflex arc.
Answer
In this reflex arc, the skin receptors detect the pin prick and send sensory signals via a sensory neurone (neuron X) to the spinal cord, where the signal is processed. A motor neurone (neuron Y) then carries the response signal from the spinal cord to the muscles, resulting in quick withdrawal of the finger. The brain is informed of the injury afterwards.
Step 5
Describe how alcohol and caffeine have different effects on reaction times.
Answer
Caffeine is a stimulant that increases the speed of neural transmission, often leading to quicker reaction times. It enhances alertness and concentration. Conversely, alcohol is a depressant that impairs brain function and slows down reaction times, leading to delayed responses and decreased coordination. The contrasting effects highlight caffeine's ability to enhance performance while alcohol diminishes it.