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The diagram shows a reflex arc - OCR Gateway - GCSE Biology (Combined Science) - Question 13 - 2023 - Paper 7
Question 13
The diagram shows a reflex arc. Receptor in foot (i) Draw lines to connect the letters, X, Y and Z, to the correct name of each neurone. X Y Z Motor Relay Se... show full transcript
Worked Solution & Example Answer:The diagram shows a reflex arc - OCR Gateway - GCSE Biology (Combined Science) - Question 13 - 2023 - Paper 7
Step 1
Step 2
Explain how the reflex arc in the diagram produces this response.
Answer
When the foot steps on a sharp object, the receptors in the skin detect the stimulus (pressure or pain). This triggers electrical impulses that travel along the sensory neurone (Z) to the spinal cord. The spinal cord rapidly processes this information and immediately sends impulses via the relay neurone (Y) to the motor neurone (X). The motor neurone then stimulates the muscle in the leg to contract, pulling the foot away from the sharp object, thus protecting the body from injury.
Step 3
Compare the roles of adrenaline and thyroxine in the body.
Answer
Adrenaline is primarily involved in the body's 'fight or flight' response. It increases heart rate, enhances blood flow to muscles, and prepares the body for rapid action. In contrast, thyroxine regulates metabolism, influencing how the body uses energy and supporting growth and development. While adrenaline has immediate effects, thyroxine supports long-term metabolic processes.
Step 4
Explain the change in blood insulin levels between 90 and 120 minutes.
Answer
Between 90 and 120 minutes after glucose intake, the blood insulin level drops from 980 mmol/l to 160 mmol/l. This decrease occurs because insulin is released to help cells absorb glucose after ingestion, and as the glucose levels in the blood decrease after this initial spike, insulin levels also decrease to maintain homeostasis.