17

Q1. Blood analysis of a patient reveals an unusually high quantity of carboxyhaemoglobin content. Which of the following conclusions is most likely to be correct? The patient has inhaled polluted air containing high content of 

• Carbon dioxide
• Carbon monoxide
• Carbon disulphide
• Chloroform

Solution

The patient has inhaled polluted air containing a high content of carbon monoxide. Carbon monoxide combines more readily with haemoglobin than oxygen. It forms a stable compound, carboxyhaemoglobin, which reduces the amount of free haemoglobin available for carrying oxygen and starves the tissues of oxygen. Deficiency of oxygen causes headache, dizziness, nausea, paralysis and even death.

Q2. Respiration results in 

• Release of O₂
• Anabolism
• Transfer of CO₂
• Release of CO₂

Solution

Respiration is a catabolic process which involves uptake of oxygen by tissue cells, oxidation of food by oxidising enzymes inside the cells and release of carbon dioxide from body tissues.

Q3. Severe acute respiratory syndrome (SARS)  

• Is caused by a variant of Pneumococcus pneumonae  
• Is caused by a variant of the common cold virus (corona virus)  
• Is an acute form of asthma  
• Affects non-vegetarians much faster than vegetarians  

Solution

Severe acute respiratory syndrome (SARS) is caused by human coronavirus. It spreads through contact, respiratory secretions and cockroaches. The main symptoms include cold, dry cough, headache, loss of appetite and fever.   

Q4. The pharynx opens into the larynx by a slit-like aperture called  

• Epiglottis  
• Glottis  
• Trachea  
• Bronchus  

Solution

The pharynx opens into the larynx by a slit-like aperture called the glottis, which is covered by a cartilaginous flap called the epiglottis. The epiglottis closes the glottis to prevent the entry of food particles during swallowing.  

Q5. Pulmonary tuberculosis is caused by

• Rhinovirus
• Corona virus
• Mycobacterium tuberculosis
• Corynebacterium diphtheriae

Solution

Pulmonary tuberculosis (TB) is caused by Mycobacterium tuberculosis. It affects the lungs and the pleura. The bacteria destroy parts of the lung tissue, and the tissue is replaced by fibrous connective tissue.

Q6. Binding of oxygen with haemoglobin tends to displace carbon dioxide from the blood. This phenomenon is called  

• Chloride shift  
• Hamburger shift  
• Haldane effect  
• None of the above  

Solution

Binding of oxygen with haemoglobin tends to displace carbon dioxide from the blood. This phenomenon is called Haldane effect. It occurs because the combination of oxygen with haemoglobin causes it to become a stronger acid which, in turn, displaces carbon dioxide from the blood.  

Q7. Which of the following is the cofactor of carbonic anhydrase?   

• Fe  
• Zn  
• Cu  
• Mg  

Solution

Carbonic anhydrase is a zinc-activated enzyme, so its cofactor is zinc.  

Q8. The total number of alveoli in both lungs are 

• 300 million
• 3000 million
• 300 billion
• 3000 billion

Solution

There are about 300 million alveoli in both the lungs which increase the surface area for the exchange of respiratory gases.

Q9. It is known that exposure to carbon monoxide is harmful to animals because   

• It reduces CO₂ transport.  
• It reduces O₂ transport.  
• In increases CO₂ transport.  
• It destroys haemoglobin.  

Solution

Carbon monoxide is harmful to animals because it combines more readily with haemoglobin than oxygen forming the stable compound carboxyhaemoglobin and thus destroys free haemoglobin.   

Q10. Inflammation of pleural membranes causes

• asphyxia
• pleurisy
• anoxia
• emphysema

Solution

In pleurisy, the pleural membranes surrounding the lungs get inflamed and scrape against each other during breathing. The symptoms include fever, cough, shallow breathing and pain in chest.

Q11. A person breathes in some volume of air by forced inspiration after having a forced expiration. This quantity of air taken in is   

• Total lung capacity  
• Tidal volume  
• Vital capacity  
• Inspiratory capacity  

Solution

A person breathes in some volume of air by forced inspiration after having a forced expiration. This quantity of air taken in is the total lung capacity. It is equal to the sum of the vital capacity and the residual volume.   

Q12. Dead space air in man is  

• 500 ml  
• 150 ml  
• 250 ml  
• 1.5 l  

Solution

Of 500 ml of inspired air, only 350 ml of fresh air reaches the lung alveoli and is called alveolar volume while about 150 ml of inspired air remains in the respiratory tract which is called anatomical dead space volume.  

Q13. Alveoli become enlarged and damaged with reduced surface area in heavy smokers. The condition is called   

• Silicosis  
• Emphysema  
• Asthma  
• Bronchitis  

Solution

In Emphysema, over inflation of the alveoli and rupture of alveolar walls occur. This decreases the surface area and pulmonary ventilation.   

Q14. The term ‘Glycolysis’ has originated from the Greek words 

• Glycose and lysis
• Glycos and lysis
• Glyco and lysis
• Glucose and lysis

Solution

The term ‘Glycolysis’ has originated from the Greek words ‘glycos’ and ‘lysis’. ‘Glycos’ means sugar and ‘lysis’ means splitting. 

Q15. In Hamburger’s phenomena, which ion is transported?

• Mg⁺⁺
• Na⁺
• Cl⁻
• K⁺

Solution

The movement of chloride ions is called the chloride shift or Hamburger phenomenon. Chloride ions diffuse from the plasma into the erythrocytes to restore the ionic balance when the bicarbonate ions are transported during carbon dioxide transport.

Q16. RQ of fat is

• More than one
• One
• Less than one
• Infinite

Solution

The ratio of the volume of carbon dioxide produced to the volume of oxygen used in a unit time is called respiratory quotient (RQ). The fats are hydrolysed to glycerol and fatty acids. The fatty acids are poor in oxygen, so they require more oxygen for their complete oxidation. Therefore, the absorption of oxygen is more than the liberation of carbon dioxide, and thus, RQ becomes less than unity.

Q17. After deep inspiration, maximum expiration of lungs is called 

• Vital capacity
• Total lung capacity
• Inspiratory capacity
• Functional residual capacity

Solution

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 is called vital capacity.

Q18. The vital capacity of the lungs includes   

• IRV + TV + ERV  
• ERV + RV  
• IRV + TV  
• RV + ERV + TV + IRV  
• ERV + TV  

Solution

The vital capacity is the total of the tidal volume, inspiratory reserve volume and expiratory reserve volume.  

Q19. The amount of volume of air which can be inspired/expired normally is called   

• Tidal volume  
• Vital capacity  
• Residual volume  
• Normal volume  

Solution

Tidal volume is the volume of air normally inspired or expired in one breath without any effort. It is about 500 ml in the average human adult male.   

Q20. During hibernation, the frog respires through   

• Gills  
• Lungs  
• Integument  
• Tympanum  

Solution

During hibernation, cutaneous respiration occurs in the frog, i.e. it respires through its moist skin or integument. The skin is permeable to respiratory gases and carries oxygen to the body cells for respiration.   

Q21. The partial pressure of oxygen in the lungs is 

• 100 mm Hg
• 110 mm Hg
• 40 mm Hg
• 60 mm Hg

Solution

The partial pressure of oxygen in the lungs or alveolar air is approximately 100 mm Hg, while that of oxygen in the venous blood in pulmonary arterial capillaries is 40 mm Hg on an average. Due to a PO₂ difference between air and blood, oxygen diffuses rapidly from the alveolar air into the blood. 

Q22. What are the causes of asphyxia?

• drowning
• pneumonia
• cyanide poisoning
• all of these

Solution

Asphyxia is a condition caused by interruption in the supply of oxygen to the tissues. This may be caused due to: 1. Due to drowning (alveoli get filled with water) 2. Due to pneumonia (filled with tissue fluid and mucus) 3. Due to cyanide poisoning which inactivates one of the enzymes responsible for the utilisation of oxygen in the cells.

Q23. In which of the following animals, respiration occurs without any respiratory organ?   

• Frog  
• Fish  
• Cockroach  
• Earthworm  

Solution

The earthworm breathes through its thin and moist skin.     Oxygen is absorbed and transported to all the cells of the body where it is utilised for respiration.  

Q24. The bulk of CO₂ released from body fluids into the blood is present as   

• Bicarbonate in blood plasma and RBCs  
• 70% as carbaminohaemoglobin and 30% as bicarbonate  
• Free CO₂ in blood plasma  
• Carbaminohaemoglobin in RBCs  

Solution

About 70% of carbon dioxide released by respiring tissue cells diffuses into the plasma and then into red blood cells, where it combines with water to form carbonic acid.  

Q25. Increased asthmatic attacks in certain seasons are related to

• Low temperature
• Hot and humid environment
• Eating fruits preserved in containers
• Inhalation of seasonal pollen

Solution

Increased asthmatic attacks in certain seasons are related to inhalation of pollen grains of plants (e.g. congress plant). Asthma is characterised by narrowing and inflammation of bronchi, bronchospasm and difficulty in breathing.

Q26. The majority of carbon dioxide produced by our body cells is transported to the lungs 

• Attached to haemoglobin
• Dissolved in the blood
• As bicarbonates
• As carbonates

Solution

About 70% of carbon dioxide is transported from the body tissues to the lungs as sodium and potassium bicarbonates.

Q27. 1200 ml volume of air which always remains in the lungs even after forcible expiration is called  

• Tidal volume  
• Residual volume  
• Vital capacity  
• Inspiratory volume  

Solution

Residual volume is the volume of air which always remains in the lungs even after forcible expiration. It is about 1100-1200 ml.  

Q28. The lungs are enclosed in a covering called 

• Pericardium
• Pleural membrane
• Peritoneum
• Perichondrium

Solution

Each lung is enclosed by a thin, transparent, two-layered membrane called the pleural membrane. The inner membrane is called visceral pleuron and the outer membrane is called parietal pleuron. Between these two membranes, a cavity called the pleural cavity is present which is filled with a watery fluid called the pleural fluid.

Q29. Which one of the following mammalian cells is not capable of metabolising glucose to carbon dioxide aerobically?  

• Red blood cells  
• White blood cells  
• Unstriated muscle cells  
• Liver cells  

Solution

Red blood cells are not capable of metabolising glucose to carbon dioxide aerobically because they lack mitochondria which are the sites of aerobic respiration.  

Q30. Lungs have a large number of narrow tubes called

• Alveoli
• Bronchioles
• Bronchi
• Tracheae

Solution

The trachea divides into a pair of thin-walled tubular structures called bronchi. Each bronchus enters a lung where it divides into secondary and tertiary bronchi. Tertiary bronchi further divide into smaller branches called bronchioles.

Q31. Oxygen is carried by 

• Leucocytes
• Erythrocytes
• Platelets
• None of the above

Solution

Erythrocytes or RBCs are capable of binding oxygen as it has a haemoglobin pigment which contains a haem part and a protein part in its structure. The haem part of the haemoglobin structure contains four atoms of iron, each capable of combining with a molecule of oxygen. Oxygen combines with haemoglobin to form oxyhaemoglobin and is carried to different body cells. 

Q32. Residual volume is 

• Lesser than tidal volume
• Greater than inspiratory volume
• Greater than vital capacity
• Greater than tidal volume

Solution

Residual volume is always greater than tidal volume. Tidal volume is the volume of air normally inspired or expired in one breath without any effort, and the residual volume of air is the air which remains in the lungs even after forcible expiration. Tidal volume is about 500 ml, whereas residual volume is about 1100-1200 ml. 

Q33. One molecule of haemoglobin carries how many molecules of oxygen?  

• Four
• Two
• Eight
• Six

Solution

One molecule of haemoglobin carries four molecules of oxygen. The haem part of the haemoglobin structure contains four atoms of iron, each capable of combining with a molecule of oxygen. 

Q34. About 97% of O₂ is transported by RBCs. The remaining 3%  

• Is dissolved in plasma and transported
• Remains in the lungs
• Is in peroxisomes
• Is attached to cell membranes
• Is inside the mitochondria

Solution

About 1-3% of oxygen is transported by the blood in the dissolved form in blood plasma.

Q35. The oxygen dissociation curve is

• Parabolic
• Hyperbolic
• Sigmoid
• Straight

Solution

An oxygen dissociation curve is the graph showing the percent saturation of haemoglobin with the changes in partial pressure of oxygen at constant pH. The curve shows that there is a progressive increase in the percent saturation of haemoglobin with the increase in partial pressure of oxygen up to a level, and then it becomes constant. So, a normal oxygen dissociation curve is sigmoid.

Q36. The state during which the respiratory centre is inhibited is termed

• asphyxia
• chocking
• anoxia
• suffocation

Solution

Anoxia is the condition characterized by an absence of oxygen supply to an organ or a tissue. Here the respiratory centre is inhibited.

Q37. One reason for emphysema is

• liquor consumption
• smoking
• drug addiction
• heavy exercise

Solution

Cigarette smoking is by far the biggest culprit for people developing emphysema, and it is also the most preventable cause

Q38. Mosquito receives air through   

• Flagellum  
• Cilia  
• Pedicel  
• None of the above  

Solution

The mosquito receives air through spiracles which enters the trachea and transports the respiratory gases into the body cells.   

Q39. The number of gills present in Osteichthyes is  

• 2 pairs  
• 6-15 pairs  
• 5 pairs  
• 4 pairs  
• 12 pairs  

Solution

Osteichthyes have 4 pairs of gill slits covered by the operculum.  

Q40. In humans, which among these is not a step in respiration?  

• Pulmonary ventilation  
• Alveolar diffusion of O₂ and CO₂  
• Transport of gases by blood  
• Diffusion of O₂ and CO₂ between blood and tissues  
• Utilisation of CO₂ by cells for catabolic reactions