Tiêu đề Ex- 2 Breathng and Exchange of Gases (Solution file).docx.pdf ✅

105 BREATHING AND EXCHANGE OF GASES EXERCISE – 2: Previous Year Questions 1. Assertion (A): A person goes to high altitude and experiences 'altitude sickness' with symptoms like breathing difficulty and heart palpitations. Reason (R): Due to low atmospheric pressure at high altitude, the body does not get sufficient oxygen. (NEET 2021) (a) If both assertion and reason are true and reason is the correct explanation of assertion. (b) If both assertion and reason are true but reason is not the correct explanation of assertion. (c) If assertion is true but reason is false. (d) If both assertion and reason are false. Ans. (a) Sol. A person goes to high altitude and experiences altitude sickness with symptoms like breathing difficulty and heart palpitations because in the low atmospheric pressure of high altitudes, the body does not get enough oxygen. 2. Select the favorable conditions required for the formation of oxyhaemoglobin at the alveoli. (NEET 2021) (a) High pO2 , low pCO2 , less H + , lower temperature (b) Low pO2 , high pCO2 , more H + , higher temperature (c) High pO2 , high pCO2 , less H + , higher temperature (d) Low pO2 , low pCO2 , more H + , higher temperature Ans. (a) Sol. High pO2 , low pCO2 , lesser H + concentration and lower temperature are all favorable factors for the formation of oxyhaemoglobin at the alveoli. 3. The partial pressures (in mmHg) of oxygen (O2) and carbon dioxide (CO2) at alveoli (the site of diffusion) are: (NEET 2021) (a) pO2=104 and pCO2=40 (b) pO2=40 and pCO2=45 (c) pO2=95 and pCO2=40 (d) pO2=159 pO2=159 and pCO2=0.3 Ans. (a) Sol. In the alveolar air, the partial pressure of oxygen (pO2) is 104 mmHg and that of carbon dioxide (pCO2) is 40 mmHg. 4. Select the correct events that occur during inspiration. (NEET 2020) (i) Contraction of diaphragm (ii) Contraction of external intercostal muscles (iii) Pulmonary volume decreases (iv) Intra pulmonary pressure increases (a) (i),(ii) and (iv) (b) Only (iv) (c) (i) and (ii) (d) (iii) and (iv) Ans. (c) Sol. Inspiration is initiated by contraction of diaphragm which increases volume of thoracic chamber in antero-posterior axis and contraction of external intercostal muscles which lifts up the ribs and sternum causing increases in volume of thoracic chamber in dorsoventral axis. 5. Identify the wrong statement with reference to transport of oxygen. (NEET 2020) (a) Higher H + conc. in alveoli favors the formation of oxyhaemoglobin (b) Low pCO2 in alveoli favors the formation of oxyhaemoglobin (c) Binding of oxygen with haemoglobin is mainly related to partial pressure of O2 (d) Partial pressure of CO2 can interfere with O2 binding with haemoglobin. Ans. (a)
106 BREATHING AND EXCHANGE OF GASES Sol. The Oxygen dissociation curve is highly useful in studying the effect of factors like pCO2 , H + concentration, etc., on binding of O2 with haemoglobin. In the alveoli, where there is high pO2 , low pCO2 , lesser H + concentration and lower temperature, the factors are all favorable for the formation of oxyhaemoglobin. In the tissues, where low pO2 , high pCO2 , high H + concentration and higher temperature exist, the conditions are favorable for dissociation of oxygen from the oxyhaemoglobin. 6. The Total Lung Capacity (TLC) is the total volume of air accommodated in the lungs at the end of a forced inspiration. This includes: (NEET 2020) (a) RV; IC (Inspiratory Capacity); EC (Expiratory Capacity); and ERV (b) RV; ERV; IC and EC (c) RV; ERV; VC (Vital Capacity) and FRC (Functional Residual Capacity) (d) RV (Residual Volume); ERV (Expiratory Reserve Volume); TV (Tidal Volume); and IRV (Inspiratory Reserve Volume) Ans. (d) Sol. The total Lung Capacity is the total volume of air accommodated in the lungs at the end of a forced inspiration. This includes RV (Residual Volume); ERV (Expiratory Reserve Volume); TV (Tidal Volume); and IRV (Inspiratory Reserve Volume). 7. Match the items given in Column I with those in Column II and select the correct option given below: (NEET 2020) Column I Column II a. Pneumotaxic center i. Alveoli b. O2 dissociation curve ii. Pons region of brain c. Carbonic anhydrase iii . Haemoglobin d Primary site of gas exchange iv . R.B.C. (a) a-i, b-iv, c-ii, d-iii (b)a-iii, b-i, c-iv, d-ii (c) a-ii, b-iii, c-iv, d-i (d) a-iv, b-iii, c-ii, d-i Ans. (c) Sol. Alveoli are primary site of gas exchange. Exchange of gases also occur between blood and tissues. A sigmoid curve is obtained when percentage saturation of haemoglobin with O2 is plotted against the pO2 . This curve is called the oxygen dissociation curve. RBCs contain a very high concentration of the enzyme, carbonic anhydrase which converts water and carbon dioxide into carbonic acids. Carbonic acid converts into carbonate also due to action of same enzyme. This enzyme facilitates the reaction in both directions. Pons region of brain contain Pneumotaxic center. 8. Due to increasing air-borne allergens and pollutants, many people in urban areas are suffering from respiratory disorder causing wheezing due to: (NEET 2019) (a) inflammation of bronchi and bronchioles (b) proliferation of fibrous tissues and damage of the alveolar walls (c) reduction in the secretion of surfactants by pneumocytes (d) benign growth on mucous lining of nasal cavity. Ans. (a) Sol. Asthma is a difficulty in breathing causing wheezing due to inflammation of bronchi and bronchioles. It can be due to increasing air born allergens and pollutants. Asthma is an allergic condition. Many people in urban areas are suffering from this respiratory disorder. 9. Tidal volume and expiratory reserve volume of an athlete is 500 mL and 1000 mL respectively. What will be his expiratory capacity of the residual volume is 1200 mL? (NEET 2019) (a) 1700 mL (b) 2200 mL (c) 2700 mL (d) 1500 mL Ans. (d) Sol. Tidal volume is the volume of air inspired or expired during a normal respiration. It is approx. 500 mL.
107 BREATHING AND EXCHANGE OF GASES Expiratory reserve volume is additional volume of air, a person can expire by a forcible expiration. This averages 1000 mL to 1100 mL. Expiratory capacity is total volume of air a person can expire after a normal inspiration. This includes tidal volume and expiratory reserve volume (TV+ERV). So Expiratory capacity = 500 + 1000= 1500 mL 10. Select the correct statement. (NEET 2019) (NEET 2019) (a)Expiration occurs due to external intercostal muscles (b) Intrapulmonary pressure is lower than the atmospheric pressure during inspiration (c) Inspiration occurs when atmospheric pressure is less than intrapulmonary pressure. (d)Expiration is initiated due to contraction of diaphragm. Ans. (b) Sol. Inspiration occurs when the pressure within the lungs (intra-pulmonary pressure) is less than the atmospheric pressure. Relaxation of the diaphragm and the internal inter-costal muscles returns the diaphragm and sternum to their normal positions and reduce the thoracic volume and thereby the pulmonary volume. This leads to an increase in intra-pulmonary pressure to slightly above the atmospheric pressure causing expiration. 11. The maximum volume of air a person can breathe in after a forced expiration is known as (NEET 2019) (NEET 2019) (NEET 2019) (a) Expiratory Capacity (b) Vital Capacity (c) Inspiration Capacity (d) Total Lung Capacity Ans. (b) Sol. Vital capacity is the maximum volume of air a person can breathe in after a forced expiration. This includes Expiratory Reserve Volume, Tidal Volume and Inspiratory Reserve Volume, or the maximum volume of air a person can breathe out after a forced inspiration. 12. Which of the following options correctly represents the lung conditions in asthma and emphysema, respectively? (NEET 2018) (a) Increased respiratory surface; Inflammation of bronchioles (b) Increased number of bronchioles; Increased respiratory surface (c) Inflammation of bronchioles; Decreased respiratory surface (d) Decreased respiratory surface; Inflammation of bronchioles Ans. (c) Sol. In Asthma there is no change in the respiratory surface of the lungs. It's an allergic response to a stimulus caused by inflammation of the bronchioles. Emphysema is caused due to loss of the alveolar surface over a while due to inflammatory response on the alveolus. This reduces the respiratory surface. 13. Match the items given in Column I with those in Column II and select the correct option given below: (NEET 2018) Column I Column II a. Tidal volume i. 2500-3000 mL b. Inspiratory Reserve volume ii. 1100-1200 mL c. Expiratory Reserve volume iii . 500-550 mL d Residual volume iv. 1000-1100 mL (a) a-i, b-iv, c-ii, d-iii (b)a-iii, b-i, c-iv, d-ii (c) a-iii, b-ii, c-i, d-iv (d) a-iv, b-iii, c-ii, d-i Ans. (b) Sol. The tidal volume of a normal person is 500-550mL. The inspiratory reserve volume is 2500-3000 mL and the expiratory reserve volume is 1000-1100 mL. The amount of air that remains in the lungs i.e., the residual volume is 1100-1200 mL. 14. Which of the following is an occupational respiratory disorder? (NEET 2018)
108 BREATHING AND EXCHANGE OF GASES (a) Botulism (b)Silicosis (c) Anthracis (d) Emphysema Ans. (b) Sol. Botulism (Food poisoning) caused by Clostridium botulinum is a gastrointestinal disease. Bacillus anthracis is a causative agent of anthrax. Silicosis is caused due to gradual depositions of silica dust in the lungs. This is found in the persons involved in the silica occupation (sand, rock, cement factory). Emphysema is the result of chronic irritation to the lung mucosa, e.g., Cigarette smoking. 15. Lungs are made up of air-filled sacs, the alveoli. They do not collapse even after forceful expiration, because of. (NEET 2017) (a) Residual Volume (b) Inspiratory Reserve Volume (c) Tidal Volume (d) Expiratory Reserve Volume Ans. (a) Sol. Inspiratory reserve volume is the amount of air forcefully inspired after a normal inspiration. Tidal volume is the normal amount of air inspired/expired during normal breathing. Expiratory reserve volume is the amount of volume forcefully expired after a normal expiration. Residual volume is the amount of air that remains in the lungs even after maximum forceful expiration. It prevents the collapse of alveoli/lungs. 16. Name the chronic respiratory disorder caused mainly by cigarette smoking (NEET 2016) (a) Emphysema (b) Asthma (c) Respiratory acidosis (d) Respiratory alkalosis Ans. (a) Sol. The particles in the smoke of the cigarette cause inflammation of the alveoli resulting in the loss of alveolar surface over time. This condition is called emphysema. Asthma is an allergic response to multiple stimuli present in the environment. Respiratory alkalosis and acidosis is caused when the oxygen-carbon dioxide amount is disturbed in the body. 17. Asthma may be attributed to (NEET 2016) (a) Bacterial infection of the lungs (b) Allergic reaction of the mast cells in the lungs (c) Inflammation of the trachea (d) Accumulation of fluid in the lungs Ans. (b) Sol. Asthma is a chronic inflammatory disease caused by the hyper response of the tracheobronchial tree to many stimuli. It is basically a hyper reaction response to a stimulus, which is normally ignored in a normal person. 18. Reduction in pH of blood will (NEET 2016) (a) Reduce the rate of heartbeat (b) Reduce the blood supply to the brain (c) Decrease the affinity of hemoglobin with oxygen (d) Release bicarbonate ions by the liver Ans. (c) Sol. Reduction of pH means an increase in H + ions. This is when the pCO2 is high and carbon dioxide is diffused in blood in the form of bicarbonate ions. High pCO2 reduces the affinity of Hb with oxygen leading to its dissociation and CO2 is carried away. This happens in tissue areas. 19. It is much easier for a small animal to run uphill than for a large animal, because (NEET 2016) (a) It is easier to carry a small body weight (b) Smaller animals have a higher metabolic rate (c) Small animals have a lower O2 requirement (d) The efficiency of muscles in large animals is less than in the small animals Ans. (b) Sol. Smaller animals have a higher metabolic rate than larger animals. This allows them to provide more oxygen and flush out more CO2 from the tissues. Also in muscles, when the aerobic respiration is not possible due to low Oxygen availability, lactic acid produced due to anaerobic respiration, does not get accumulated in large amounts thus making the animal feeling less tired helping them run uphill faster. 20. The partial pressure of oxygen in the alveoli of the lungs is (NEET 2016) (a) equal to that in the blood (b) more than that in the blood (c) less than that in the blood (d) less than that of carbon dioxide Ans. (b) Sol. The partial pressure of oxygen in the alveoli (104 mmHg) is more than that of the blood (40 mmHg). This results in diffusion of Oxygen from the alveolar