1
IB DIPLOMA
BIOLOGY
TEST
QUESTIONS
ON
HOMEOSTASIS
1.Arterioles in the skin contain muscle fibres which contract.
What is the function of these fibres?
A.To move capillaries further from the skin when the body is too
cold
B.To reduce blood flow to the skin when the body is too cold
C.To move capillaries closer to the skin when the body is too
warm
D.To increase blood flow to the skin when the body is too
warm
(Total 1 mark)
2.Under what conditions is glucagon secretion increased?
A.After fasting for a long period
B.While resting
C.After a meal rich in carbohydrates
D.When the temperature falls
(Total 1 mark)
3.Which of the following is closely associated with lowering of
high body temperature?
A.Constriction of blood vessels in the skin
B.Vasodilation of blood vessels in the skin
C.Increased shivering
D.Decreased sweat production
(1)
4.Which cells secrete insulin?
A.b-cells of the pancreas
B.Cells of the liver
C.a-cells of the pancreas
D.Epithelial cells of the intestine
(1)
5.Which process decreases when the human body temperature
decreases?
A.Blood flow to the internal organs
B.Secretion of sweat
C.Secretion of insulin
D.Shivering
(Total 1 mark)
6.How do endocrine glands function when they are involved in
homeostasis?
A.They release hormones directly into the blood system.
B.They release hormones through ducts to where they are
used.
C.They release digestive enzymes from the pancreas.
D.They cause positive feedback in the bodys structures.
(Total 1 mark)
7.What can be changed in the kidney over a period of time in
order to carry out the process of osmoregulation?
A.The amount of blood flowing to the kidney
B.The amount of fluid filtered from the blood in the
glomeruli
C.The amount of solutes selectively reabsorbed in the proximal
convoluted tubule
D.The amount of water reabsorbed in the collecting ducts
(Total 1 mark)
8.Which best describes the role of the kidney in
homeostasis?
A.Storage of urine
B.Producing urine at a constant rate
C.Removing urea from the blood
D.Maintaining the water content of the blood between narrow
limits
(Total 1 mark)
9.The diagram shows how the body regulates glucose levels in the
blood.
Glucose increase
Glucose normal
Glucose decrease
Y
released
X
released
What is Y?
A.Amylase
B.Insulin
C.Glucagon
D.Glycogen
(Total 1 mark)
10.In thermoregulation, what would happen over a short period of
time in each of these areas, if a person was placed in water at 15C
?
Peripheral circulation
Sweat glands
Liver
Skeletal muscle
A
Increased blood flow
Increased secretion
Decreased temperature
Decreased shivering
B
Decreased blood flow
Decreased secretion
Decreased temperature
Increased shivering
C
Decreased blood flow
Increased secretion
No change in temperature
Increased shivering
D
Decreased blood flow
Decreased secretion
No change in temperature
Increased shivering
(Total 1 mark)
11.Intravenous nutrition is used in patients who cannot feed by
mouth. Introducing nutrients directly into veins bypasses the rate
at which the digestive system absorbs them. Scientists studied the
effect of injecting six different glucose concentrations into rats.
They measured the glucose concentration in the urine per day and
the glucose concentration in blood plasma per day. These values
were compared to control rats that received the same six glucose
concentrations through the mouth. The percentage of rats that died
during the experiment (mortality) was measured. The results for all
control rats orally fed with six different glucose concentrations
were the same and are shown in the table below.
Urine glucose concentration /mmol dm3
Blood plasma glucoseconcentration / mmol dm3
Mortality / %
0
10
0
The results for the injected rats are shown in the line graph
below.
(a)State the mortality for rats when injected with 110 mmol dm3
glucose.
....................................................................................................................................
(1)
(b)Estimate the difference in blood plasma glucose concentration
between rats injected with 145 mmol dm3 glucose and the blood
plasma glucose concentration of control rats orally fed 145 mmol
dm3 glucose.
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(1)
(c)Using the data, explain the conclusions that can be drawn
about the ability of the rats to regulate blood plasma glucose
levels successfully.
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(3)
(d)Suggest reasons for the differences between rats that were
injected and the rats that were orally fed high levels of glucose
concentrations.
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(2)
(Total 7 marks)
12.(a)(i)Define the term homeostasis.
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(1)
(ii)State which two systems are involved in the control of
homeostasis.
1................................................................................................................
2................................................................................................................
(1)
(b)Describe the roles of the kidney in homeostasis.
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(2)
(c)Using an example, explain the role of negative feedback in
homeostasis.
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(3)
(Total 7 marks)
13.The plasma solute concentration, plasma antidiuretic hormone
(ADH) concentration and feelings of thirst were tested in a group
of volunteers. These graphs show the relationship between intensity
of thirst, plasma ADH concentration and plasma solute
concentration.
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10
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0
20
18
16
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12
10
8
6
4
2
0
280
280
290
290
300
300
310
310
320
320
Plasma solute concentration / mOsmol kg
Plasma solute concentration / mOsmol kg
1
3
1
[Source: adapted from C T Thompson, et al., (1986), Clinical
Science London, 71, page 651]
(a)Identify the plasma ADH concentration at a plasma solute
concentration of 300 mOsmol kg1 using the line of best fit.
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(1)
(b)Compare intensity of thirst and plasma ADH concentration.
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(1)
(c)Outline what would happen to plasma solute concentration and
ADH concentration if a person were to drink water to satisfy
his/her thirst.
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(2)
(d)State two reasons why a persons plasma solute concentration
may increase.
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(2)
(Total 6 marks)
14.(a)Explain briefly the principle of negative feedback in
homeostasis.
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(3)
(b)Draw an arrow on the diagram below to show where negative
feedback occurs.
Decreased
Body
Temperature
Temperature
Receptors
Response
e.g.
Sweat Glands
Decreased Sweating
Skin Arterioles
Decreased Blood Flow
Skeletal Muscle
Shivering
Increased
Body
Temperature
(1)
(c)State the system used to control the response of the skin
arterioles.
....................................................................................................................................
(1)
(Total 5 marks)
15.The effect of different types of meals before exercise was
tested on metabolism and performance for twelve competitive
cyclists. The cyclists ingested either high fat or high
carbohydrate meals before the start of exercise.
The test consisted of:1 hour of cycling at half peak power
(pre-load)followed by five 10 minute incremental increases in
intensity (load)and a 50 km time trial.
The concentration of various hormones in the blood plasma of the
cyclists was measured. The graphs below indicate the change in
insulin and glucagon levels before and during the cycling test.
Pre-
load
Incremental
test (load)
50 km
time trial
Key:
High fat
High carbohydrate
80
60
40
30
20
15
10
5
3
240
200
160
120
100
80
60
50
40
30
20
Insulin concentration /
mU dm
(log scale)
Glucagon concentration /
ng dm
(log scale)
3
3
100
60
20
20
60
100
140
160
Test duration / min
[Source: Rowlands and Hopkins, International Journal of Sport
Nutrition and Exercise Metabolism,(2002), 12, page 318]
(a)Describe the changes in insulin concentration during the
course of the exercise period for those cyclists who ate a high
carbohydrate meal.
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(2)
(b)Compare the changes in insulin and glucagon concentration
during the pre-load and incremental test period.
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(2)
(c)Using the data provided, outline how the changes illustrate
negative feedback of insulin and glucagon.
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(2)
(Total 6 marks)
16.Explain how blood glucose concentration is controlled in
humans.
(Total 8 marks)
