(a) In humans humans,, normal normal body temperature temperature is maintain maintained ed by by a number number of different different mechanisms. If body temperature changes, information is sent to the temperature regulating centre, which then makes the appropriate response to bring body temperature back to normal.
1.
In some extreme situations, if the temperature-regulating mechanisms fail, body temperature may fall below 35 °C.
(i)
Name the part part of of the brain in which which the the temperatu temperature-reg re-regulating ulating centre is situated situated.. ………………………………………………………………………………… (1)
(ii)
What term term is used to describe describe the conditio condition n in which body temperature temperature falls below 35 °C? ………………………………………………………………………………… (1)
(b)
In an invest investigatio igation n into body temper temperature, ature, the oral oral (mouth) (mouth) temperatu temperature re of a healthy healthy person was measured every five minutes for 40 minutes. From five minutes after the start of the investigation until 20 minutes, the person was lying in a hot bath, at a temperature of 42 °C. After 20 minutes the person got out of the bath and sat on a c hair. The results of this investigation are shown in the table below. Time/min
Oral temperature/°C
0 (start of investigation)
37.0
5
37.0
10
37.2
15
37.8
20
37.9
25
37.7
30
37.5
35
37.2
40
37.0
1
(i)
Describe Describe the the changes changes in oral oral temper temperature ature which occurred occurred during during the the investig investigation. ation. ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… (3)
(ii)
Suggest Suggest explanatio explanations ns for for the changes changes in oral temper temperature ature which occurred occurred between between the following time intervals. 0 to 20 minutes ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… …………………………………………………………………………………
20 to 40 minutes ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… (5) (Total 10 marks)
2.
During investigations into the control of body temperature, the internal (core) body temperature of a thin human volunteer was recorded at intervals. In the first investigation, the volunteer sat still for 30 minutes. He then got i nto water at 16 °C, where he lay still for a further 30 minutes. In the second investigation, the body temperature of the same volunteer was recorded at intervals for thirty minutes while he was sitting still. He t hen went swimming in water at 16 °C for 30 minutes and his body temperature was again recorded while he was swimming, and immediately after he stopped. The results are shown in the table below.
Time / minutes
First investigation Body temperature / °C
Second investigation Body temperature / °C
0
37.5
37.4
15
37.6
37.5
30
37.5 [got into water]
36.9 [started swimming]
40
37.3 [lying in water]
36.0 [swimming]
50
37.1 [lying in water]
35.2 [swimming]
60
36.8 [lying in water]
34.2 [stopped swimming]
(a)
State where in the the body the temperaturetemperature-regul regulating ating centre is situated. situated. .......................................................................... ................................................................................................................ ................................................................. ........................... (1)
(b)
Explain Explain why the the voluntee volunteer’s r’s body body temperatu temperature re decreased decreased when he he was lying lying in water at at 16 °C. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… (2)
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(c) (c)
(i) Compa ompare re the chan change gess in body ody temp emperat eratu ure when hen the the volu volun nteer teer was was lying in water with the changes when he was swimming. ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… (3)
(ii)
Suggest Suggest an explanatio explanation n for the the differenc differencee in the change change in body body temperatu temperature re when the person was swimming, compared to lying still in water. ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… ……………………………………………………………………………………… (2) (Total 8 marks)
3.
The table below shows the blood flow to cardiac muscle and to the skin at different levels of exercise. 3
Blood flow/cm per minute Level of exercise
Cardiac muscle
Skin
Rest
250
500
Low intensity
350
1500
Medium intensity
650
1800
High intensity
1800
1000
(a) (a)
(i) Calcu alcula late te the perce ercen ntage tage incr increa ease se in the the rate rate of bloo blood d flo flow to card cardia iacc muscle as the level of exercise increases from resting to a medium level of intensity. Show your working.
Answer .................................. .................................. (2)
(ii)
Explain Explain why cardiac cardiac muscle muscle requires requires a greater greater rate of of blood blood flow as the intensity intensity of exercise increases. ......................................................................... ............................................................................................................... ...................................................... ................ ......................................................................... ............................................................................................................... ...................................................... ................ ......................................................................... ............................................................................................................... ...................................................... ................ ......................................................................... ............................................................................................................... ...................................................... ................ (2)
(b)
An increase increase in blood blood flow to the skin skin allows allows more more heat heat to be lost lost through through radiation radiation and sweating. This helps to prevent the body temperature from rising above normal during exercise. (i)
Compare Compare the the changes changes in blood blood flow to to cardiac cardiac muscle muscle and to the the skin, skin, as as exercis exercisee increases from low intensity to high intensity. ......................................................................... ............................................................................................................... ...................................................... ................ ......................................................................... ............................................................................................................... ...................................................... ................ ......................................................................... ............................................................................................................... ...................................................... ................ ......................................................................... ............................................................................................................... ...................................................... ................ (2)
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(ii)
Suggest explanations for the changes changes in blood flow to the skin as exercise increases from low intensity to high intensity. ......................................................................... ............................................................................................................... ...................................................... ................ ......................................................................... ............................................................................................................... ...................................................... ................ ......................................................................... ............................................................................................................... ...................................................... ................ ......................................................................... ............................................................................................................... ...................................................... ................ ......................................................................... ............................................................................................................... ...................................................... ................ ......................................................................... ............................................................................................................... ...................................................... ................ (3) (Total 9 marks)
(a) Describe Describe the the mechanis mechanisms ms that that prevent prevent the core body temperature temperature falling falling below below normal.
4.
.......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... (3)
(b)
Infections such as tuberculosis can cause fever, where the body temperature is maintained above normal. The graph below shows the temperature of one person with an infection and one uninfected person with normal body temperature.
T e m / º C
p
e
r a
t u
r e I n f e c p e r s o U p
n e
i n r s o
(i)
State the location location of of the the temperat temperature-r ure-regulat egulating ing centre in the human body. ......................................................................... ............................................................................................................... .................................................. ............ (1)
(ii)
Suggest Suggest how changes changes in the tempera temperature-r ture-regula egulating ting centre centre result result in the maintenance maintenance of a higher body temperature during a fever. ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ (1)
(iii)
Explain how how the higher body body temperature of the infected person helps in combating an infection. ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ (2)
(c)
Describe Describe what what will will happen happen to an infected infected person person if heat is is generated generated by the the body at a faster rate than it can be lost. .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... (3) (Total 10 marks)
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5.
An investigation was carried out into body temperature regulation in humans. A healthy volunteer was immersed in a bath of water at 10 °C. During t he investigation he kept one hand in the air and one hand submerged in water. The temperature of the hand in air and the temperature of the hand in water were recorded immediately after he got into t he bath, and then every minute for seven minutes. His core (internal) temperature was also recorded and found to remain at almost exactly 37 °C. The air temperature in the room remained at 26 °C during the investigation. The results are shown in the graph below. T /
e m º C 2
p
e
r a
t u
r e
6
T 2
4
2
2
2
0
1
8
1
6
1
4
1
2
1
0
e
T
0
1
m
e
p
e
m
p
r a
e
t u
r a
r e
t u
o
r e
f
o
f
2 T
i m
e
/
(a)
Compare Compare the the temperatur temperaturee of the hand hand in air with with the temperature temperature of the the hand immersed immersed in water during this investigation. .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... (2)
(b)
Suggest Suggest reason reasonss for for the the differences differences you have described described in (a). (a). .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... (2)
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(c)
Suggest Suggest why why the volunteer’s volunteer’s core temperature temperature remained remained almost almost constant constant during during this this investigation. .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... .......................................................................... ................................................................................................................ ............................................................ ...................... (3) (Total 7 marks)
6.
(a)
The diagram diagram below shows shows a section section through through human skin.
(i)
Name Name the parts parts labelled labelled A, B and C. A. ........................................................................ ................................................................................................................ ............................................... ....... B ....................................................................... ............................................................................................................. ................................................. ........... C ....................................................................... ............................................................................................................. ................................................. ........... (3)
(ii)
Explain Explain the the role role of part C in the regulation regulation of body body temperature temperature.. ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ (3)
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(b)
In an investigati investigation, on, a number number of naked men sat sat in a room, room, maintaine maintained d at an air air temperature of 15 °C, for two hours. After this time their core (internal) body temperature was measured. Their percentage body fat was also measured. The results of this investigation are shown in the graph below. 3
7
. 5 × ×
3 C b
o
o d
7
. 0
× ×
×
×
×
×
× ×
×
×
×
× ×
× ×
× ×
×
. 0 0
2
4
6
8 P
(i)
×
×
×
×
6
×
×
r e ( i n t e r n a l ) y t e m p e r a t u r e / ° C 3 6 . 5
3
×
×
1
0
e
r c
1
2 e
1 n
4
1
6
t a
g
e
1
8 b
2 o
0 d
2 y
2 f a
2 t
Describe Describe the trend shown by these results. results. ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ (2)
(ii)
Suggest Suggest explanation explanationss for these results. results. ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ ......................................................................... ............................................................................................................... .................................................. ............ (3) (Total 11 marks)
7.
A person at rest produces enough heat to raise the body temperature by 1.0 °C per hour. The table below shows how this excess heat can be lost. Means of heat loss
% of total heat loss
Conduction of heat to other objects
2
Convection due to air currents
8
Radiation from skin surface
60
Evaporation of sweat
30
13
Heat loss by sweating is not possible when the humidity is 100%, for example in a tropical rainforest. (a)
Assuming Assuming that that the other means of heat heat loss loss remain remain unchang unchanged, ed, calcula calculate te the time it would take the body temperature to reach 42°C from a normal temperature of 37 °C in a rainforest. Show your working.
Answer ............................................... ............................................... (3)
(b)
This increase in body temperature could be fatal. Describe the mechanisms that could could prevent it from happening. .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... (5) (Total 8 marks)
8.
Human body temperature is controlled by negative feedback. (a)
Describe Describe and and explain explain how negativ negativee feedback feedback controls controls human body temperature temperature.. .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... (5)
(b)
Explain Explain how some some infection infectionss interfere interfere with the the temperatur temperaturee regulation regulation mechanisms mechanisms of of the human body. .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... (2) (Total 7 marks)
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9.
An investigation was carried out into the effect of having a hot bath on the core body temperature of a man. The man measured his body temperature, then lay in a bath of water a t a temperature of 42°C for 10 minutes. After 10 minutes, he got out of the bath and sat on a chair. He took readings of his body temperature at regular time intervals during the investigation. The results are shown in the table below. Time / min
Body temperature / °C
0 (start of investigation)
37.0
5 (got into bath)
37.0
10 (got out of bath)
37.8
15 (sitting on chair)
37.6
20 (sitting on chair)
37.4
Describe and suggest explanations for the changes in body temperature during each of the following time intervals. (i) (i)
5 to 10 minu minute tess .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... .....................
(ii) (ii)
10 to 20 minut minutes es .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... (Total 4 marks)
10.
The temperature of the human body is kept within narrow limits by negative feedback mechanisms. (a)
Following Following a rise in in core core temperatu temperature, re, describ describee the sequence sequence of of events events in in the body that returns the temperature to normal. .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... (3)
(b)
Describe how this response might be different in a person infected with tuberculosis. .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... (2)
(c)
Explain Explain how a forensic forensic scientis scientist’s t’s estimate estimate of of time of death death could could be affected affected if the victim had tuberculosis. .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... .......................................................................... ................................................................................................................ ........................................................... ..................... (2) (Total 7 marks)
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