Fig. 1 shows a control pathway that operates when the temperature of blood reaching the brain rises above its normal value. Boxes P, Q and R have not been c...
Question 1 Report
Fig. 1 shows a control pathway that operates when the temperature of blood reaching the brain rises above its normal value. Boxes P, Q and R have not been completed.
(a) Name the part of the brain that detects the temperature change and would be written in box P. [1]
(b) Complete box Q with one response occurring in the skin. [1]
(c) Complete box R with the effect of this response on body temperature. [1]
(d) Explain why this pathway is described as negative feedback. [2]
(e) State one other response that may occur when blood temperature is too high. [2]
Answer Details
(a) Box P is the hypothalamus. [1] This region of the brain monitors the temperature of the blood.
(b) A correct skin response for box Q is: sweat glands produce sweat. Skin blood vessels dilating is also acceptable. [1]
(c) The effect in box R is that body temperature falls, returning towards normal. [1]
(d) This is negative feedback because the response opposes the original rise in temperature and so returns body temperature towards its normal set point. [2]
(e) Two linked further responses are: hairs lie flat, so less insulation is provided. Increased blood flow through skin capillaries is also acceptable. [2]
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