Topic 7 Gas exchange in humans Directions: The following two questions refer to the diagram below, which shows a group of cells from the respiratory tract. X Y 1. What is the function of structure X? A. To trap dust particles. B. To move the mucus. C. To provide a larger surface area for gas exchange. D. To warm up the incoming air. 2. The correct label of Y is A. mucus-secreting cell B. ciliated epithelial cell C. capillary D. muscle cell 3. Which of the following structures is/are found in the nasal cavity? (1) ciliated epithelium (2) mucus-secreting cells (3) hairs A. (1) only B. (1) and (2) only C. (1) and (3) only D. (1), (2) and (3)
4. The trachea is supported by many C-shaped cartilages. These cartilages A. trap dust particles and bacteria B. warm up the inhaled air C. vibrate and produce sound D. keep the trachea open for breathing 5. Which of the following is/are true for air sacs? (1) They have a thick epithelial wall. (2) They are well-supplied with capillaries. (3) They provide a large surface area. A. (1) only B. (2) and (3) only C. (1), (2) and (3) D. none of the above 6. Which of the following pairs comparing inhaled and exhaled air is correct? Inhaled air Exhaled air A 21% oxygen 16% oxygen B 4% carbon dioxide 0.03% carbon dioxide C saturated with water vapour variable amount of water vapour D about 37oC variable temperature 7. The diagram below shows some air sacs in the human lungs. Which of the following features of the air sacs contribute to their high efficiency of gas exchange? A. moist surface, thin lining and large surface area B. moist surface, supported by cartilage and large surface area C. thin lining, richly supplied with blood and ball-like structures
D. thin lining, richly supplied with blood and supported by cartilage 8. The efficiency of gas exchange in lungs is increased by A increasing the length of the trachea B increasing the number of white blood cells flowing into the lungs C increasing the thickness of the walls of the bronchioles D increasing the surface area of the air sacs 9. Which of the following is the function of the pleural membranes? A. They secrete a fluid which lubricates the lungs during breathing movements. B. They give the lungs a pink colour. C. They help the lungs expand during inspiration. D. They help the diaphragm change pressure during breathing. 10. Mary is breathing into and out of an airtight bag. Which of the following graphs about the change in the respective gas component inside the bag is incorrect? amount of gas C. number of breaths oxygen number of breaths amount of gas nitrogen B. carbon dioxide number of breaths D. amount of gas amount of gas A. SHAPE \* MERGEFORMAT water vapour number of breaths 11. Which of the following is the correct match of the process and its description? Process Description A inhalation bringing fresh air to the lungs and removing carbon
B C D ventilation breathing gas exchange dioxide from the lungs increasing the volume of the thoracic cavity moving air into and out of the lungs decreasing the volume of the thoracic cavity 12. Which of the following events occur during exhalation in humans? (1) Diagram contracts. (2) Intercostal muscles relax. (3) Rib cage moves inwards and downwards. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 13. The percentages of which of the following gases in exhaled and inhaled air differ? (1) oxygen (2) nitrogen (3) water vapour A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 14. Which of the following is the correct pathway of air leaving the lungs during exhalation? A. air sac --> bronchiole --> bronchus --> trachea B. bronchiole --> air sac --> trachea --> bronchus C. bronchiole --> air sac --> bronchus --> trachea D. air sac --> bronchiole --> trachea --> bronchus Directions: Questions 15, 16 refer to the diagram below, which shows an experimental set-up used to study the effect of oxygen on citrated chicken blood.
15. What will be the change in the colour of the blood? A. from bright red to purplish red B. from purplish red to bright red C. from bright red to blue D. no colour change 16. Which of the following statements are correct? (1) The colour change is reversible if carbon dioxide is bubbled into the blood. (2) Haemoglobin is purplish red. (3) At high carbon dioxide concentration, oxyhaemoglobin forms. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 17. The graph below shows the relationship between oxyhaemoglobin and the concentration of carbon dioxide in the blood.
concentration of oxyhaemoglo bin in blood (%) concentration of CO2 in blood (%) Which of the following statements correctly describes this relationship? A. The concentration of oxyhaemoglobin increases with the increase in carbon dioxide concentration. B. The concentration of oxyhaemoglobin decrease with the decrease in carbon dioxide concentration. C. The concentration of oxyhaemoglobin decreases with the increase in carbon dioxide concentration. D. The concentration of oxyhaemoglobin is not affected by the concentration of carbon dioxide. 18. Carbon monoxide has a higher affinity for haemoglobin than oxygen. Inhalation of excessive carbon monoxide can be fatal. This happens because the capacity of red blood cells for carrying A. carbon dioxide is decreased. B. carbon dioxide is increased. C. oxygen is decreased. D. oxygen and carbon dioxide is decreased. Directions: The following two questions refer to the bell-jar model below, which shows the process of inhalation in humans. air rushes into Y W Y inflates X Y Z 19. Which structure of the human breathing system does X represent?
A. B. C. D. the lungs the thoracic wall the sternum the intercostal muscles 20. What happens if Z is pushed upwards? A. X would move upwards and air would be forced out from W B. X would move downwards and Y would deflate C. Y would deflate and air would be forced out from W D. Y would inflate and air would rush in through W 21. Frogs prefer to live in damp place because A. they are afraid of light B. their surfaces of lungs must keep moist for breathing C. it is warmer in damp place D. their skin must keep moist for breathing Directions: Questions 22 to 23 refer to the diagram below which shows an apparatus used for investigating cigarette smoke. 22. What are the colors of the cotton wool and the hydrogen carbonate indicator after the experiment? Cotton wool Indicator orange A. Brown B. Brown yellow C. Red orange D. White Yellow
23. Which components of the cigarette smoke are responsible for the color changes? (1) carbon monoxide (2) carbon dioxide (3) nicotine (4) tar A. B. C. D. (1) and (2) only (1) and (4) only (2) and (3) only (2) and (4) only Directions: Questions 24 to 26 refer to the graph below which shows the changes in the lung capacity of a man. 24. What is the volume of air inspired by the man during a normal breath? A. 0.5 dm3 B. 1.0 dm3 C. 1.5 dm3 D. 2.5 dm3 25. What is the maximum volume of air which the man can breathe out in a single breath? A. 0.5 dm3 B. 2.5 dm3 C. 3.0 dm3 D. 5.0 dm3
26. What is the amount of air inside the lungs after the man has made a forced expiration? A. 0.5 dm3 B. 1.0 dm3 C. 2.5 dm3 D. 3.0 dm3 Directions: Questions 27 to 29 refer to the graphs below which shows the breathing rate of a man after various physiological condirions. 27. Which of the following descriptions of the graph is correct? X Y Z A. Running Reading Sleeping B. Reading Running Sleeping C. Sleeping Running Reading D. Reading Sleeping Running 28. The breathing rate shown in Y is, in breathes min-1 A. 6 B. 12 C. 24 D. 48 29. What is the relation between the breathing rate and the breathing volume as shown in the graphs? A. Breathing volume increases when breathing rate increase B. Breathing volume decreases when breathing rate increase C. There is no change in breathing volume when breathing rates increases D. There is no direct relationship between the two