Biology. TOPIC : Breathing and Exchange of Gases. Marks : 120 mks Time : ½ hr

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(i) Animal having external gills (ii) Animal having internal gills (iii) Animal showing tracheal respiration (iv) Animal revealing buccopharyngeal espiration.

1 TOPIC : Breathing and Exchange of Gases Date : Marks : 120 mks Time : ½ hr (1) Read the given statements characterizing certain types of animals. Select the option that correctly exemplifies each of these types. (i) Animal having external gills (ii) Animal having internal gills (iii) Animal showing tracheal respiration (iv) Animal revealing buccopharyngeal espiration. (i) (ii) (iii) (iv) (a) Prawn Arenicola Unio Fish (b) Necturus Unio Prawn Frog (c) Pila Arenicola Unio Toad (d) Necturus Pila Millipide Toad (2) Study the given figure of respiratory passage carefully and identify the parts labeled as A, B C, D and E. A B C D E (a) Alveolar sac Secondary bronchus Alveoli Bronchioles Trachea (b) Alveoli Secondary bronchus Alveolar sac Trachea Bronchioles (c) Alveolar sac Tertiary bronchus Alveoli Trachea Bronchioles (d) Alveoli Tertiary bronchus Alveolar sac Bronchioles Trachea (3)Match Column-I with Column-II and select the correct option from the codes given below Column-I (Animals) A Pigeon i Book gills B Scorpion ii Pharyngeal wall C Planaria iii Lungs D Earthworm iv Gills E Spiders v Book lungs F King Crab vi Body surface G Prawn vii Skin H Labeo Page 1 of 9 Column-II (Respiratory structures)

2 (a) A-(iii), B-(v), C-(vi), D-(vii), E-(v), F-(i), G-(iv), H-(iv). (b) A-(v), B-(ii), C-(iv), D-(vii), E-(vi), F-(iv), G-(i), H-(iii). (c) A-(vi), B-(iv), C-(vii), D-(v), E-(i), F-(ii), G-(iii), H-(vii). (d) A-(i), B-(v), C-(vii), D-(iii), E-(vii), F-(ii), G-(iv), H-(vi). (4) In lungs, the air is separated from various blood through (a) transitional epithelium + tunica externa of blood vessel (b) squamous epithelium + endothelium of blood vessel (c) squamous epithelium + externa media of blood vessel (d) none of these (5) Vital capacity of lungs is (a) IRV + ERV (b) IRV + ERV + TV RV (c) IRV + ERV + TV + RV (d) IRV + ERV + TV (6) Which of the following sequences is correct to initiate inspiration? (i) The contraction of external intercostal muscles raise the ribs and sternum (ii) Volume of thorax increases in the dorso-ventral axis (iii) Intrapulmonary pressure decreases (iv) Diaphragm contraction (v) Air rushes into lungs (vi) Volume of thorax increases in the anterior-posterior axis (a) (i), (ii), (iv), (v),(iii), (vi) (b) (i), (ii), (iii), (iv), (vi), (v) (c) (i), (ii), (iv), (vi), (iii), (v) (d) (vi), (v), (i), (ii), (iii), (iv) (7) Match Column-I with Column-II and select the correct option from the codes given below Column-I Column-II A Tidal volume i M=ml of air B Inspiratory reserve volume ii 1000 ml of air C Expiratory reserve volume iii 500 ml of air D Residual volume iv ml of air E Vital capacity v 2000 ml of air (a) A-(iii), B-(iv), C-(ii), D-(i), E-(v) (b) A-(iii), B-(i), C-(ii), D-(v), E-(iv) (c) A-(iii), B-(i), C-(iv), D-(v), E-(ii) (d) A-(v), B-(i), C-(ii), D-(iii), E-(iv) Page 2 of 9

3 (8) After forceful inspiration, the amount of air that can be breathed out by maximum force expiration is equal to (a) Inspiratory Reserve Volume (IRV) + Expiratory Reserve Volume (ERV) + Tidal Volume (TV) + Residual Volume (RV) (b) IRV +RV +ERV (c) IRV + TV +ERV (d) TV + RV + ERV (9) Consider the following statements each with one or two blanks. (i) Left lungs has (1) lobes and right lungs has (2) lobes (ii) Prawn respires with (3) and inserts with (4) (iii) Amount of air inhaled and exhaled with maximum effort is referred to as the (5) of the lungs Fill up the above by selecting the correct option. (a) (1)-three, (2)-two, (3)-gills, (4)-tracheae (b) (1)-two, (2)-three, (5)-vital capacity (c) (3)- gills, (4)-tracheae, (5)-tidal volume (d) (3)-tracheae, (40-gills, (5)-tidal volume (10) Fill up the blanks in the following paragraph by selecting the correct option. The movement of air into and out of the lungs is carried out by creating a (i) between the lungs and the atmosphere. Inspiration can occur if intra-pulmonary pressure is (ii) than the atmospheric pressure. Expiration takes place when the intra-pulmonary pressure is (iii) than the atmospheric pressure. Inspiration is initiated by the (iv) of the diaphragm which (v) the volume of thoracic chamber in the antero-posterior axis. (i) (ii) (iii) (iv) (v) (a) Concentration less higher relaxation increases gradient (b) Concentration higher less contraction decreases gradient (c) Pressure higher less relaxation decreases gradient (d) Pressure less higher contraction increases gradient (11) In the tissues, high concentration of carbon- dioxide (a) Increases the affinity of haemoglobin to oxygen and hydrogen (b) Increases the affinity of haemoglobin to oxygen but decreases its affinity to hydrogen (c) decreases the affinity of haemoglobin to oxygen but increases its affinity to hydrogen (d) decreases the affinity of haemoglobin to both oxygen and hydrogen (12) People living at sea level have around 5 million RBC per cubic millimeter of their blood whereas those living at an altitude of 5400 meters have around 8 million. This is because at high altitude (a) people eat more nutritive food, therefore more RBC s are formed (b) people get pollution-free air to breathe and more oxygen is available (c) atmosphere O 2 level is less and hence more RBCs are needed to absorb the required amount of O 2 to survive (d) There is more UV radiation which enhances RBC production 3 P a g e

4 (13) Given below is the list of different steps (i-iv) involved in respiration (i) Utilization of O 2 by the cells for catabolic reactions. (ii) Transport of gases by the blood. (iii) Pulmonary ventilation by which atmospheric air is drawn in and CO 2 is released out. (iv) Relase of resultant CO 2 (v) Diffusion of O 2 and CO 2 between blood and tissues (vi) Diffusion of gases (O 2 and CO 2) across alveolar tissues. Select an option which has correct sequence of all the steps (a) (iii), (vi), (ii), (v), (i), (iv) (b) (iii), (vi), (i), (v), (ii), (iv) (c) (iv), (ii), (v), (iii), (i), (vi) (d) (iv), (vi), (ii), (v), (i), (iii) (14) The graph given shows an oxygen dissociation curve for haemoglobin Where in the body will haemoglobin be saturated at the percentage shown at points 1, 2, 3 on the graph? Left Ventricle Pulmonary vein Vena curve (a) (b) (c) (d) (15) Chemosensitive area of respiratory centre in medulla is affected by (a) Less CO 2 and H + ions (b) Less O 2 and H + ions (c) Excess CO 2 and H + ions (d) Excess O 2 and H + ions (16) Match Column-I with Column-II and select the correct option from the codes given below Column-I Column-II A Yeast i Inspiration B Diaphragm ii Hamburger s phenomenon C Insects iii Diffusion of CI-icons into RBC s D Pons varolii iv Fermentation E Chloride shift v Trachea vi Pneumotaxic centre vii Expiration Page 4 of 9

5 (a) A-(iv), B-(i),(vii) C-(v), D-(vi), E-(ii),(iii) (b) A-(v), B-(i), C-(iv),(vii) D-(vi), E-(ii), (iii) (c) A-(ii), (vi) B-(i), C-(iii), D-(v), E-(vii), (iv) (d) A-(iii), B-(i), C-(ii), (v) D-(vi), (vii), E-(iv) (17) Match Column-I with Column-II and select the correct option from the codes given below Column-I Column-II A Trachea i Alveolar air Po2 B Respiratory centre ii ATP C Yeast iii Cartilaginous rings D Insects iv Medulla oblongata E Fish v Larynx F Biologically useful energy vi Tracheal respiration G 100 mm Hg vii Ethanol H Vocal cords viii Branchial respiration (a) A-(iii), B-(iv), C-(vii), D-(vi), E-(viii), F-(ii), G-(i), H-(v) (b) A-(v), B-(ii), C-(vii), D-(viii), E-(vi), F-(iv), G-(i),H-(iii) (c) A-(vi), B-(iv), C-(viii), D-(v), E-(i), F-(ii), G-(iii),H-(vii) (d) A-(i), B-(v), C-(vii), D-(iii), E-(viii), F-(ii), G-(iv),H-(vi) (18) The given figure shows diagrammatic representation of exchange of gases at the alveolus and the body tissues with blood and transport of oxygen and carbon dioxide. Identify the blood vessels A to D A B C D (a) Systematic Vein Pulmonary artery Pulmonary vein Systematic artery (b) Systematic artery Pulmonary artery Pulmonary vein Systematic Vein (c) Pulmonary artery Systematic Vein Pulmonary vein Systematic artery (d) Systematic Vein Pulmonary vein Pulmonary artery Systematic artery 5 P a g e

6 (19) Which structure of man is similar to the spiracle of cockroach? (a) Nostril (b) Bronchiole (c) Lungs (d) Alveoli (20) Mammalian lungs have an enormous number of minute alveoli (air sacs). This is to allow (a) more surface area for diffusion of gases (b) more space for increasing the volume of inspired air (c) more nerve supply to keep the lungs working (d) more spongy texture for keeping the lung in proper shape (21) Which one of the following statements is incorrect? (a) the principle of counter current flow facilitates efficient respiration in gills of fishes (b) the residual air in lungs slightly decreases the efficiency of respiration in mammals (c) the presence of non-respiratory air sacs, increases the efficiency of respiration in birds (d) in insects, circulating body fluids serve to distribute oxygen to tissues. (22) Which of the following changes occur in diaphragm and intercostals muscles when expiration of air takes place? (a) External intercostals muscles relax and diaphragm contracts (b) External intercostals muscles contracts and diaphragm relaxes (c) External intercostals muscles and diaphragm relax (d) External intercostals muscles and diaphragm contracts (23) The ventilation movements of the lungs in mammals are governed by (a) muscular walls of lung (b) diaphragm (c) coastal muscles (d) both (b) and (c) (24) The factor which does not affect the rate of alveolar diffusion is (a) solubility of gasses (b) thickness of the membrane (c) pressure gradient (d) reactivity of the gases (25) Foetal haemoglobin has X affinity for oxygen than that of mother s haemoglobin during gestation. X is (a) same (b) higher (c) lower (d) lower affinity earlier but higher later (26) When temperature decreases, oxy-hb curve becomes (a) more steep (b) straight (c) parabola (d) none of these (27) Emphysema is a condition resulting from (a) cigarette smoking (b) Liquor consumption (c) drug addiction (d) reduced oxygen carrying capacity of blood (28) The oxygen dissociation curve is (a) parabola (b) slope (c) sigmoid (d) straight line Page 6 of 9

7 (29) The exchange of gases in the alveoli of the lungs takes place by (a) passive transport (b) active transport (c) osmosis (d) simple diffusion (30) The partial pressure of oxygen is maximum in (a) alveolar air (b) arterial blood (c) venous blood (d) expired air 7 P a g e

8 SOLUTION 1. (d) : Necturus (Mud puppy, Amphibia) possesses three pairs of external gills. Pila ( Applle snail, Mollusca) respires by means of gills (ctenidium) in water and by a pulmonary sac on land. Millipedes (Athropoda) respire by trachea (tracheal respiration) and toads (Amphibia) exhibit buccopharyngeal respiration. 2. (a) 3. (a) 4. (b) : The wall of the alveoli is very thin and has a rich network of blood capillaries. The alveolar capillary membrane consists mainly of squamous epithelium, epithelial basement membrane, a thin interstitial space, capillary basement membrane and capillary endothelium. 5. (d) : Vital capacity is the maximum volume of air a person can breathe in after a forced expiration or the maximum volume of air a person can breathe out after a forced inspiration. This equals the inspiratory reserve volume (IRV) + expiratory reserve volume (ERV) + tidal volume (TV). Its value is 3400ml 4800 ml. 6. (c)i 7. (b) 8. (c) Vital capacity is the maximum volume of air a person can breathe in after a forced expiration or the maximum volume of air a person can breathe out after a forced inspiration. This equals the inspiratory reserve volume (IRV) + expiratory reserve volume (ERV) + tidal volume (TV). Its value is 3400ml 4800 ml. 9. (b) : Prawn respires with gills (Branchial respiration) and insects respire by trachea (Traceal respiration). 10. (d) 11. (c) : Increase in the CO2 content of the blood decreases the ph of the blood. This decreases the affinity of O2 with Hb. This is called the Bohr effect and is closely related to the fact that deoxygenated Hb binds hydrogen ions more actively than does the Hb. This facilitates gaseous exchange because more O2 is released in the tissues where the amount of CO2 is more due to metabolic activity. At the same time, more O2 is taken up by the lungs or gills when the amount of CO2 is low. 12. (c) : Number of RBC per cubic millimetre of the blood is likely to be higher in people living at high altitudes. This is in response to the air being less dense at high altitude and thus more RBCs (and hence more Hb) are needed to absorb the required amount of O2 from the air having low po (a) 14. (c) : The relationship between the partial pressure of O2 (po2) and percentage saturation of the Hb with O2 is graphically illustrated by a curve called oxygen dissociation curve. The haemoglobin is most saturated with oxygen in the pulmonary vien, as this vien is carrying oxygenated blood from lungs towards the left auricle of the heart. From the left auricle the blood moves to the left ventricle where saturation of Hb and O2 slightly reduces. Vena cava carries deoxygenated blood from the organs to the body towards right auricle. The Hb is less saturated with O (c) :Respiratory rhythm centre is a specialised centre present in the medulla of the brain which is primarily responsible for the regulation of respiration. A chemosensitive area situated adjacent to the rhythm centre is highly sensitive to changes in CO2 and hydrogen ions concentrations in the blood. Increase in CO2 and H+ ions stimulate this centre, which in turn stimulate the rhythm centre to make necessary adjustments in the respiratory process by which these substances can be eliminated. 16. (a) 17. (a) : Trachea consists of C-shaped cartilaginous rings that support the walls of the trachea and prevent its collapse during inspiration. Respiratory centre is located in the medulla oblongata. Yeast undergoes anaerobic respiration to produce ethanol and CO2. The type of respiration in insects and fish is tracheal respiration and branchial respiration respectively. ATP is a biologically useful energy produced respiration. The partial pressure of O2 in alveolar air is approximately 104mm Hg. Vocal cords are present inside the larynx. Page 8 of 9

9 18. (a) 19. (a) : Spiracle in cockroach an nostril in man are the openings through which air enters the body. 20. (a) : The number of alveoli in the human lungs has been estimated to be approximately 300 million. This enormous number of alveoli are meant to increase surface area of lungs for diffusion of gases. 21. (d) : In insects blood (haemolymph) does not contain an oxygen-carrying pigment. Hence it does not help in respiration. Instead, insects have spiracles and trachea that carry O2 to different tissues. 22. (c) : When the external intercostal muscles and diaphragm relax, the ribs move downward and inward and diaphragm becomes convex (dome shaped), thus decreasing the volume of thoratic cavity and increasing the pressure inside as compared to the atmospheric pressure outside. This will cause the air to move out (expiration) 23. (d) : During inspiration, the muscles of the diaphragm contract, thus making it flat and thereby increasing the volume of the thoratic cavity. The external intercostal muscles of the ribs also contract, thus pulling the ribs upward and outward and thereby, increasing the volume of the thoratic cavity,decreases the pressure inside as compared to the atmospheric pressure outside, thus making the air form outside to enter the lungs (inspiration).when the external intercostal muscles and diaphragm relax, the ribs move downward and inward and diaphragm becomes convex (dome shaped), thus decreasing the volume of thoratic cavity and increasing the pressure inside as compared to the atmospheric pressure outside. This will cause the air to move out (expiration) 24. (d) : O2 and CO2 are exchanged in the alveoli by simple diffusion. The factors that affect the diffusion are pressure gradient of the gases, solubility of the gases and the thickness of the membrane involved in diffusion. 25. (b) : Foetal haemoglobin (also called haemoglobin F or Hb F) is the main oxygen transport carrier in human foetus during the last seven months of development in the uterus and persists in the newborn until it is about 6 months old. Functionally, foetal haemoglobin has a higher affinity to bind with oxygen molecules that the adult (or maternal )haemoglobin, giving the developing foetus better acess to oxygen from the mother s bloodstream. 26. (a) : When the temperature decreases, oxy-hb curve will become more steep.the steep rise of the curve indicates high affinity of Hb for O (a) : Emphysema is a respiratory disorder which occurs due to inflation or abnormal distension of the bronchioles or the alveolar sacs resulting in the loss of the elasticity. Cigarette smoking and chornic bronchitis are the causes of the deseases. 28. Oxygen Disscociation curve (ODC) is a sigmoid curve i.e S-shaped. Each Hb molecule has four haem groups and to each group one molecule of O2 binds. Thus each Hb molecule and combine with four O2 molecules. The first part of the ODC is not very steep because first O2 molecule combines relatively slowly with the first haem group. However, this binding causes the shape of the whole Hb molecule to change.as a result of the altered shape it becomes easier for the second, third and fourth O2 molecules to bind to their haem groups. Thus, the ODC now becomes much steeper. As the limit of oxygen saturation ( i.e., 100%) is reached,the curve flattens, before it. 29. (d) : The exchange of gases in the alveoli of the lungs takes place by simple diffusion. The exchange of gases between the alveoli and blood in the lung is the result of difference in partial pressure of respiratory gases 30. (d) : The partial pressure of O2 in expired air is 116 mm Hg. In alveolar air it is 104mm Hg, in arterial blood it is 95 mm Hg and in venous blood it is 40 mm Hg. 9 P a g e

CHAPTER 17 BREATHING AND EXCHANGE OF GASES

268 BIOLOGY CHAPTER 17 BREATHING AND EXCHANGE OF GASES 17.1 Respiratory Organs 17.2 Mechanism of Breathing 17.3 Exchange of Gases 17.4 Transport of Gases 17.5 Regulation of Respiration 17.6 Disorders of