Breathing and exchange of gases MCQs with Answers

Question-1. Which of the following statement is true?

1. Every 100 mL of deoxygenated blood delivers approximately 4 mL of carbondioxide to the alveoli.
2. Every 100 mL of oxygenated blood delivers approximately 4 mL of oxygen to the tissues.
3. Every 100 mL of oxygenated blood delivers approximately 4 mL of carbondioxide to the alveoli.
4. Every 100 mL of deoxygenated blood delivers approximately 10 mL of carbondioxide to the alveoli.

Question-2. Which of the following statements is true about Trachea in a respiratory system?

1. It functions as passages of air to each alveolus
2. It functions for sound production
3. It Acts as passage of air to bronchi
4. It Lowers the surface tension

Question-3. Which one of the following is NOT correct?

1. The nasal cavity warms and humidifies the air before it enters the lungs
2. The right lung is composed of three lobes, but the left lung has only two lobes
3. Lung volumes and vital capacity measure lung function.
4. The visceral pleura is in direct contact with the chest wall.

Question-4. Which one of the followings is correct regarding larynx?

1. It prevents foreign objects from entering the trachea
2. It houses the vocal cords
3. It is an organ made of cartilage and connects the pharynx to the trachea
4. All of these are correct

Question-5. Which organ lies in thoracic cavity?

1. Heart
2. Lungs
3. Pancreas
4. Both 1and 2

Question-6. A large proportion of oxygen is left unused in the human blood even after its uptake by the body tissues. This O2

1. Acts as a reserve during muscular exercise
2. Raises the pCO2 of blood to 75 mm of Hg.
3. Is enough to keep oxyhaemoglobin sturation at 96%
4. Helps in releasing more O2 to the epithelial tissues

Question-7. After forceful inspiration, the amount of air that can be breathed out by maximum forced expiration is equal to

1. Inspiratory Reserve Volume (IRV) +Expiratory Reserve Volume (ERV) + Tidal Volume (TV) + Residual Volume (RV)
2. IRV + RV + ERV
3. IRV + TV + ERV
4. TV + RV + ERV.

Question-8. Although much CO2 is carried in blood, yet blood does not become acidic, because

1. it is absorbed by the leucocytes
2. blood buffers play an important role in CO2 transport
3. it combines with water to form H2CO3 which is neutralized by Na2CO3
4. it is continuously diffused through tissues and is not allowed to accumulate

Question-9. Among mammals, the efficiency of ventilation of lungs as compared to reptiles and birds is better developed by the presence of

1. ribs and costal muscles
2. only ribs
3. only costal muscles
4. diaphragm.

Question-10. Blood analysis of a patient reveals an unusually high quantity of carboxyhaemoglobin content. Which of the following conclusions is most likely to be correct?

1. The patient has been inhaling polluted air containing unusually high content of carbon disulphide
2. The patient has been inhaling polluted air containing unusually high content of chloroform
3. The patient has been inhaling polluted air containing unusually high content of carbon dioxide
4. The patient has been inhaling polluted air containing unusually high content of carbon monoxide

Question-11. Bulk of carbon dioxide (CO2) released from body tissues into the blood is present as

1. bicarbonate in blood plasma and RBCs
2. 70% carbamino- haemoglobin and 30% as bicarbonate
3. carbamino-haemoglobin in RBCs
4. free CO2 in blood plasma

Question-12. Carbon dioxide is transported from tissues to respiratory surface by only

1. plasma and erythrocytes
2. plasma
3. erythrocytes
4. erythrocytes and leucocytes

Question-13. Cartilaginous rings in trachea are incomplete at which surface?

1. Dorsal
2. Ventral
3. Lateral
4. Ventrolateral

Question-14. During inspiration the diaphragm

1. contracts and flattens
2. relaxes to become dome-shaped
3. shows no change
4. None of these

Question-15. Emphysema developes mainly because of

1. Spasm of the smooth muscles of bronchioles
2. Cigarette smoking
3. Inflammation of the alveoli
4. Allergy or hypersensitisation

Question-16. Even when there is no air in it, human trachea does not collapse due to presence of

1. Cartilaginous rings
2. Turgid pressure
3. Bony rings
4. Chitinous rings

Question-17. Factor helps in formation of oxyhaemoglobin in alveoli is

1. high pCO2
2. high pO2
3. higher H+ concentration
4. all of these.

Question-18. Gas flows into the lungs of mammals during inspiration because

1. The pressure in the lungs falls below atmospheric pressure
2. The pressure in the lungs rises above atmospheric pressure.
3. The volume of the lungs decreases
4. The diaphragm moves upward toward the lungs

Question-19. In alveoli of the lungs, the air at the site of gas exchange, is separated from the blood by

1. alveolar epithelium only
2. alveolar epithelium and capillary endothelium
3. alveolar epithelium, capillary endothelium and tunica adventitia
4. alveolar epithelium, capillary endothelium, a thin layer of tunica media and tunica adventitia

Question-20. In emphysema

1. Gas exchange area of lungs is reduced
2. Gas exchange area of lungs is increased
3. Trachea gets narrowed
4. Larynx is permanently closed

Question-21. In oxygen dissociation curve x-axis and y-axis represents.

1. x-axis?partial pressure of oxygeny-axis?percentage saturation of Hb with oxygen
2. x - a x i s ? p e r c e n t a g e s a t u r a t i o n o f haemoglobiny-axis?partial pressure of oxygen
3. x-axis?partial pressure of CO2y - a x i s ? percentagesaturation of oxyhaemoglobin with oxygen
4. x-axis?partial pressure of CO2y-axis?partial pressure of oxygen.

Question-22. Oxygen dissociation curve of haemoglobin is

1. Sigmoid
2. Hyperbolic
3. Hypobolic
4. Linear

Question-23. Oxyhaemoglobin is converted into haemoglobin during the internal respiration because

1. an enzyme splits oxyhaemoglobin
2. oxygen tension in tissue is less than capillary blood reaching tissue
3. CO2 tension is low in blood that reaches tissue
4. oxyhaemoglobin is unstable.

Question-24. People living at sea level have around 5 million RBC per cubic millimeter of their blood whereas those living at an altitude of 5400 metre have around 8 million. This is because at high altitude

1. atmospheric O2 level is less and hence,more RBCs are needed to absorb the required amount of O2 to survive
2. there is more UV radiation which enhances RBC production
3. people eat more nutritive food, therefore, more RBCs are formed
4. people get pollution-free air to breathe and more oxygen is available

Question-25. Pneumotaxic centre is present in

1. pons
2. medulla
3. cerebrum
4. lungs.

Question-26. Skin is an accessory organ of respiration in

1. human
2. frog
3. rabbit
4. lizard

Question-27. Smoking destroys the cilia in the respiratory passageways. This

1. makes it harder to keep the lungs clean
2. slows blood flow through lung blood vessels
3. decreases the surface area for respiration.
4. makes it harder to move air in and out of the lungs

Question-28. The alveolar epithelium in the lung is

1. non-ciliated columnar
2. non-ciliated squamous
3. ciliated columnar
4. ciliated squamous

Question-29. The carbon dioxide is transported via blood to lungs as

1. dissolved in blood plasma
2. in the form of carbonic acid only
3. in combination with haemoglobin only
4. carbaminohaemoglobin and as carbonic acid

Question-30. The exchange of gases in the alveoli of the lungs takes place by

1. simple diffusion
2. osmosis
3. active transport
4. passive transport

Question-31. The function of the mucus elevator in the mammalian respiratory system is to

1. trap and remove particulate matter that has entered the respiratory system.
2. stimulate contraction of rib musculature during forcible exhalation
3. produce negative pressure during inhalation
4. move surfactant from the bronchi to the alveoli

Question-32. The haemoglobin of a human foetus

1. has a lower affinity for oxygen than that of the adult
2. its affinity for oxygen is the same as that of an adult
3. has only 2 protein subunits instead of 4
4. has a higher affinity for oxygen than that of an adult

Question-33. The largest quantity of air that can be expired after a maximal inspiratory effort is called

1. vital capacity
2. residual volume
3. tidal volume
4. total lung volume

Question-34. The process of migration of chloride ions from plasma to RBC and of carbonate ions from RBC to plasma is

1. chloride shift
2. ionic shift
3. atomic shift
4. Na+ pump

Question-35. The quantity 1500 mL in the respiratory volumes of a normal human adult refers to

1. maximum air that can be breathed in and breathed out
2. residual volume
3. expiratory reserve volume
4. total lung capacity

Question-36. The structure which does not contribute to the breathing movements in mammals is

1. Larynx
2. Diaphragm
3. Ribs
4. Intercostal muscles

Question-37. The volume of air breathed in and out during normal breathing is called

1. Tidal volume
2. Explratory reserve volume
3. Vital capacity
4. None of these

Question-38. Two friends are eating together on a dining table. One of them suddenly starts coughing while swallowing some food. This coughing would have been due to improper movement of

1. Epiglottis
2. Diaphragm
3. Neck
4. Tongue

Question-39. What is the vital capacity of our lungs?

1. Inspiratory reserve volume plus tidal volume
2. Total lung capacity minus expiratory reserve volume
3. Inspiratory reserve volume plus expiratory reserve volume
4. Total lung capacity minus residual volume

Question-40. What would happen if human blood becomes acidic (low pH)

1. Oxygen carrying capacity of haemoglobin decreases
2. RBCs count increases
3. RBCs count decreases
4. Oxygen carying capacity of haemoglobin increases

Question-41. When about 1200 mL air is in the lungs after forceful expiration, it is called

1. residual volume
2. inspiratory reserve volume
3. vital capacity
4. tidal volume.

Question-42. When CO2 concentration in blood increases, breathing becomes

1. faster and deeper
2. slow and deep
3. there is no effect on breathing
4. shallower and slow

Question-43. When the blood contains a high percentage of CO2 and a very low percentage of O2, the breathing stops and the person becomes unconscious. This condition is known as

1. suffocation
2. asphyxia
3. emphysema
4. eupnea.

Question-44. When you exhale, the diaphragm

1. relaxes and arches
2. relaxes and flattens.
3. contracts and arches
4. contracts and flattens

Question-45. Which of the following changes occur in diaphragm and intercostal muscles when expiration of air takes place?

1. External intercostal muscles and diaphargm relax
2. External intercostal muscles and diaphargm contract
3. External intercostal muscles contract and diaphargm relaxes
4. External intercostal muscles relax and diaphargm contracts

Question-46. Which one of the following is a possibility for most of us in regard to breathing, by making a conscious effort ?

1. The lungs can be made fully empty by forcefully breathing out all air from them
2. One can breathe out air totally without oxygen.
3. One can breathe out air through eustachian tubes by closing both the nose and the mouth
4. One can consciously breath in and breath out by moving the diaphragm alone, without moving the ribs at all.

Question-47. Which one of the following organs in the human body is most affected due to shortage of oxygen?

1. Brain
2. Kidney
3. Skin
4. Intestine

Question-48. Which one of the following statements is incorrect ?

1. In insects, circulating body fluids serve to distribute oxygen to tissues
2. The principle of counter current flow facilitates efficient respiration in gills of fishes
3. The residual air in lungs slightly decreases the efficiency of respriration in mammals.
4. None of these

Question-49. …...............lies in front of esophagus.

1. Trachea
2. Glottis
3. Larynx
4. Epiglottis

Question-50. Aerobic respiratory pathway is also termed as….........pathway.

1. Anabolic
2. Catabolic
3. Creatine phosphate
4. Amphibolic

Question-51. Deoxygenated blood from heart comes to lungs via

1. pulmonary vein
2. systemic vein
3. pulmonary artery
4. systemic artery

Question-52. In brain, respiratory control centre lies in

1. pons
2. medulla oblongata
3. hypothalamus
4. cerebrum

Question-53. Pleura is a layer covering

1. heart
2. kidneys
3. lungs
4. brain

Question-54. RBCs, plasma and biocarbonate are the medium for transport of carbondioxide. Maximum amount of carbon dioxide is carried by

1. RBCs
2. Plasma
3. Bicarbonates
4. All RBCs and bicarbonate carried 70 per cent of carbondixide.

Question-55. Rheumatic fever can cause damage

1. Alveoli of the Lungs
2. heart valves
3. heart muscles
4. pleural membranes function

Question-56. The function of pneumotaxic centre is

1. regulate inspiration
2. regulate rhythm
3. increase heart rate
4. all of the above

Question-57. The maximum volume of air contained in the lung by a full forced inhalation is called

1. Vital capacity
2. Tidal volume
3. Total lung capacity
4. Inspiratory capacity

Question-58. The oxygen dissociation curve is shifted to the right by an increase in

1. H+ concentration
2. PCO2
3. temperature
4. All of these

Question-59. Trachea divides into bronchi at

1. 4th thoracic vertebra
2. 5th thoracic vertebra
3. 6th thoracic vertebra
4. 7th thoracic vertebra

Question-60. What protects the moist membranes of the respiratory tract?

1. Mucus and cilia
2. A c shaped cartilage rings
3. A pebbly epidermal surface
4. An acidic glands