Sense - Sense Organs 1989 Paper 1 Question 11 11 An...

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Sense Organs1989 Paper 1 Question 111989 Paper 1 Question 1111.An experiment was carried out in which a naked man was asked to stand still inside a room where he was subjected to different air temperatures. Shortly after he had reached an equilibrium state at each temperature, and based on measurements of a number of parameter then made, the following graph were obtained :(a)What evidence can be obtained from the graphs that various methods were employed by the body to increase heat loss ? Briefly explain how each of these operates.(N.B. Reference to metabolic activity is NOTrequired )(3 marks)(b)Account for the changes in skin temperature when the air temperature(i)fell from 29to 24, and(ii)rose from 31to 34.(4 marks)(c)Explain why the metabolic rate was lowest in the range of air temperature between 29and 31, and then increased when the air temperature either fell below or
rose above this range.(4 marks)(d)Suggest a possible cause for the increase in metabolic rate when the air temperature fell from 29to 24.(1 mark)(e)By means of diagram, show the mechanism operating in the body of this person to detect changes in air temperature and to stimulate the appropriate responses so as to maintain his body temperature.(5 marks)(f)If the man was given the freedom to reduce heat loss when the air temperature was at 24, suggest TWOpossible ways of doing so. Briefly explain how each of them works.(3 marks)Ans1989 Paper 1 Question 121989 Paper 1 Question 1212.Sound must exceed a certain intensity in order to be heard. The threshold intensity for detecting sounds across the audible frequency spectrum can be determined in an individual by presenting to the person sounds of various frequencies and intensity levels. The following results are the average threshold responses of two samples of people to sound presented from a loudspeaker placed directly in front of them in a soundproof room:Sound frequency (Hz)Sound threshold intensity (dB)Young adults (20 years)Aged adults (60 years)2060250500100020003000400050008000100007842171285337161878421712851022334452
160002269(a)Present the above results in graphical form on the semi-logarithmic paper provided on the opposite page (using the logarithmic scale for sound frequency, and the linear scale for sound threshold intensity).(5 marks)(b)With reference to the graph for young adults :(i)What is the most sensitive frequency range of the ear ? What other information can you obtain from the shape of this graph ?(2 marks)(ii)Describe and explain how the graph would be affected if there were excess wax accumulation in the external ear canal.(3 marks)(iii)One must speak louder in order to be heard in noisy surroundings. On the basis of this, plot another graph (label it as graph C) on the same graph paper you used in (a) to show the threshold response that would be obtained if the experiment were performed in a room with a low frequency background noise from an air-conditioner. This noise is of different intensities at different frequencies as shown below :Sound frequency (Hz)Sound intensity (dB)20 – 500600800above 1000201050(2 marks)(c)

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