Download public exam_gas exchange in humans

ECF Saint Too Canaan College
Biology public exam exercise
Gas exchange in humans
Name: ___________________
Class: _____ (
)
Date: _____________________
CE 2001_I_Q.4(b)
1. The graph below shows the changes in lung volume of a boy at rest over a period of 30 seconds:
(a) Determine the rate and depth of breathing of the boy at rest.
(2 marks)
(b) State the period of time in the first 5 seconds during which air was flowing out of the lungs.
(1 mark)
(c) Explain how the outflow of air from the lungs was brought about by the breathing
mechanism.
(4 marks)
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1.
(d) If the pleural membrane on the left side of the boy’s thorax is punctured, his left lung will
collapse while his right lung will not. What would be the change in
(i)
his breathing movement,
(1 mark)
(ii)
the air flow of his left and right lungs?
(2 marks)
CE 2003_I_Q.1(a)
2.
To study the effect of concentration of oxygen and carbon dioxide on the breathing rate, a healthy
person was asked to inhale different gas mixtures. The results are shown in the table below:
Gas mixture
Concentration of gas (%)
Breathing rate
Oxygen
Carbon dioxide
(breaths per min)
P
21
0.03
17
Q
21
4.00
34
R
16
0.03
17
S
16
4.00
34
(a) With reference to the above information, state the factor that affects the breathing rate of the
person. Explain how you arrive at your answer.
(3 marks)
(b) Which of the four gas mixtures has similar concentrations of oxygen and carbon dioxide as
exhaled air?
(1 mark)
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2.
(c) Mouth-to mouth ventilation is a method for rescuing a person who fails to breath but still has
heartbeat. It involves blowing exhaled air into the patient’s body through the mouth as
shown below:
Based on the composition of exhaled air, explain why this method can help the patient stay
alive before they can breathe again.
(2 marks)
(d) Suggest why it is necessary to do the following when carrying out mouth-to-mouth
ventilation:
(i) Tilt the patient’s head as shown in the diagram instead of letting it lie flat.
(1 mark)
(d) (ii)
Observe whether the patient’s chest rises when blowing air into the patient.
(1 mark)
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CE 2004_I_Q.1(c)(i)(ii)
3. The diagram below shows an air sac of the lung and its blood supply:
(a) Explain the importance of the water film in gaseous exchange.
(2 marks)
(b) SARS patients may have fluid accumulated in the air sacs. Explain how the accumulation of
fluid may affect the oxygen content of the blood of the patients.
(3 marks)
CE 2005_I_Q.4
4.
The photomicrograph below shows a section of a mammalian lung:
(a) With reference to two features observable in the photomicrograph, explain how lung tissue is
adapted to gas exchange.
(4 marks)
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4.
(b) Oxygen moves continuously from the air in A into the capillaries. However, the oxygen
content in A remains relatively high. Explain how this is achieved.
(2 marks)
(c) Eric wanted to compare the oxygen content of atmospheric air and exhaled air, so he
prepared two jars of gas as shown below:
(i)
Draw a labeled diagram to show a set-up that can be used to collect the air exhaled
from his lungs.
(4 marks)
(c) (ii)
Describe what Eric should do in order to compare the oxygen content of the two air
samples.
(2 marks)
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CE 2008_I_Q.3
5.
The following diagram shows part of the human respiratory system.
(a) Name structure X and describe its function.
(3 marks)
(b) Construct a flowchart to show the path of air passing from the atmosphere to the air sacs of
the lungs.
(2 marks)
(c) Asthma is a respiratory disease. When it attacks, structure Y constricts and the patient will
have breathing difficulty. Explain the effect of asthma on the rate of removal of carbon
dioxide from the blood of the lungs.
(4 marks)
Bio_public exam exercise_gas exchange in humans
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DSE PP_IB_Q.4(b)
6.
The photomicrographs below show the lung sections of a non-smoker and a smoker in the same
magnification:
With reference to these lung sections, explain why a smoker is more likely to become short of
breath than a non-smoker when performing vigorous exercise.
(3 marks)
DSE 2014_IB_Q.2
7.
The photomicrograph below shows a section of the inner wall of the human trachea:
(a) In the spaces provided, label the cells shown in the photomicrograph.
(2 marks)
(b) With reference to the features of the inner wall shown in the photomicrograph, describe how
the inner wall of the trachea can protect our body against bacterial invasion.
(3 marks)
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ECF Saint Too Canaan College
Biology revision exercise – Gas exchange in humans answer
1.
(a)
Rate of breathing = 12 breaths per minute
Depth of breathing = 500 cm3
1
1
(b)
between 0 and 2.5 second
1
(c)
Intercostal muscles relaxed, so that the ribs moved downward an inward.
Diaphragm muscles relaxed, so that the diaphragm recoiled to the dome-shape.
The thoracic / lung volume decreased
leading to an increase in air pressure in the lungs.
1
1
1
1
(d)
(i)
The breathing movements would become faster
1
(ii)
In the left lung, air flow would decrease
In the right lung, air flow would increase
1
1
(10)
2.
(a)
concentration of carbon dioxide
Because the breathing rate increase / changes with the concentration of carbon
dioxide
1
1
while it remains the same regardless of the change in oxygen concentration.
1
(b)
S
1
(c)
Exhaled air still contains 16% oxygen.
When blown into the patient’s lungs, the oxygen can be supplied to the body cells for
respiration.
1
1
(d)
(i)
To ensure the entrance of the trachea is clear / free from obstructions.
1
(ii)
To ensure that air is blown into the lungs.
1
(8)
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3.
(a)
Oxygen in air dissolves in the water film
so that it can diffuse readily through the wall of the air sac into the blood capillary
1
1
(b)
The accumulation of fluid increases the distance for diffusion / reduces the surface
area for dissolving oxygen
thereby decreases the rate of diffusion of dissolved oxygen into the blood capillaries.
Thus the oxygen content of the blood decreases / becomes lower than normal.
1
1
1
(5)
4.
(a)
The wall of A is very thin
so as to reduce the distance of diffusion of respiratory gases.
1
1
OR
A is richly supplied with blood capillaries.
This allows a rapid transport of gas to and away from the air sacs / can maintain a
steep concentration gradient of gases between A and the blood.
1
1
OR
The lung tissue is made up of numerous air sacs
so that there is a large surface area for gas exchange / the diffusion of gases.
(1)
(1)
(b)
During ventilation / breathing, some air in the lungs is replaced by fresh air
which contains a high oxygen content.
1
1
(c)
(i)
Title (T)
Workable set-up (S): inverted gas jar, collecting gas under water, tube
Label (L): water/water trough, blowing air, rubber tube, exhaled air collected
(c)
(ii)
½
1
1½
(any three)
Quality of drawing (D)
1
Put a burning candle into the gas samples. Compare the time that the candle
can burn.
1
1
(12)
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5.
(a)
X: *pleural membrane
It secretes pleural fluid
1
1
to reduce friction during breathing movement.
1
(b)
(atmosphere)  nasal cavity  pharynx  trachea  bronchiole  (air sacs)
2
(c)
Volume of the inspired air decrease.
Less fresh air mixes with the residual air, thus concentration of carbon dioxide in the
air sacs remains relatively high.
The concentration gradient of carbon dioxide between the alveolar air and the blood
becomes smaller.
The rate of removal of carbon dioxide from blood decreases.
1
1
OR
Volume of the inspired air decrease, carbon dioxide removed from air sacs to
atmosphere decreases,
thus concentration of carbon dioxide inside the lungs remains relatively high..
The concentration gradient of carbon dioxide between the alveolar air and the blood
becomes smaller.
The rate of removal of carbon dioxide from blood decreases.
1
1
(1)
(1)
(1)
(1)
(9)
6.
The no. of air sacs in the lungs of a smoker is fewer than that in a non-smoker.
This reduces the surface area for gas exchange
and hence the rate of oxygen diffusion to the blood (/ removal of carbon dioxide from the
body) is lowered in the lungs of the smoker,
so the body of the smoker responds with very rapid breathing to meet the extra demand for
oxygen (/ remove the carbon dioxide produced from respiration) during vigorous exercise.
1
1
1
(3)
7.
(a)
*ciliated epithelial cell
*mucus-secreting cell
(b)



mucus secreting cells secrete mucus to trap dust and germs from incoming air
(1)
cilia sweep the trapped dust and germs away to the throat for swallowing (1)
epithelial cells are closely packed to prevent entry of bacteria / form a physical
barrier (1)
(1)
(1)
(3)
5
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