NEET Biology MCQs Breathing and Exchange Of Gases

Each haemoglobin molecule can carry maximum of
a) Two molecules of O2 b) Three molecules of O2
c) Four molecules of O2 d) One molecules of O2
Hypoxia is caused due to
a) Lesser O2 in atmosphere b) Lesser RBC in blood
c) Lesser CO2 in atmosphere d) Both (a) and (b)
During oxygen transport, the oxyhaemoglobin at the tissue level liberates oxygen to the cells because
a) O2 concentration is high and CO2 is low b) O2 concentration is low and CO2 is high
c) O2 tension is low and CO2 tension is high d) O2 tension is high and CO2 tension is low
O2 exchange with CO2 by simple diffusion over the entire body surface takes place in
I. sponges II. Coelenterates III. Flatworms
Select the correct option to complete the given statement
a) I and II b) II and III c) I and III d) All of the above
Breathing involves …A… during which atmospheric air is drawn in and …B… by which the alveolar air is
released out.
Choose the correct option for A and B to complete the given NCERT statement
a) A-expiration; B-osmosis b) A-expiration; B-inspiration
c) A-inspiration; B-expiration d) A-inspiration; B-diffusion
If a large number of people are enclosed in a room, then
a) Oxygen decreases and carbon dioxide increases
b) Oxygen increases and carbon dioxide decreases
c) Both oxygen and carbon dioxide decreases
d) Both oxygen and carbon dioxide increases
The total number of lobes and alveoli present in both the lungs of man are
a) 17 and 30 million, respectively b) 5 and 300 million, respectively
c) 19 and 300 million, respectively d) 18 and 300 lakh, respectively
Which of the following combines irreversibly with blood haemoglobin?
a) SO2 b) O2 c) CO d) CO2
Identify the correct group of statements
I. Oxygen is carried by haemoglobin
II. Oxygen is carried by carbonic anhydrase
III. CO2 is carried by haemoglobin
IV. SO2 is carried by haemoglobin
V. Only oxygen is transported by the blood
VI. Only CO2 is transported by the blood
Choose the correct option
a) I and VI b) II and III c) IV and V d) I and III
What is true about RBCs in humans?
a) They carry about 20-25 per cent of carbon dioxide
b) They transport 99.5 per cent of oxygen
c) They transport about 80 per cent oxygen only and the rest 20 per cent of it is transported in dissolved
state in blood plasma

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d) They do not carry carbon dioxide at all

Respiratory centre of the brain is stimulated by
a) CO2 content in venous the blood b) CO2 content in arterial the blood
c) O2 content in arterial the blood d) O2 content in venous the blood
Identify 𝐴,𝐵 and 𝐶 in the given diagram and choose the correct option accordingly a) A-Alveolar cavity, B-WBC, C-Capillary wall b) A-Alveolar cavity, B-RBC, C-Systemic wall
c) A-Alveolar cavity, B-RBC, C-Capillary wall d) A-Alveolar cavity, B-WBC, C-Systemic wall
Why breathing is accelerated when the person opens his nose after holding the breathe by closing his
nose?
a) CO2 build up in the body b) CO build up in the body
c) H+ decreases in the body d) CO2 decrease in body
Listed below are four respiratory capacities (I-IV) and four jumbled respiratory volumes of a normal
human adult.
Respiratory Capacity Respirato
ry Volume
I.Residual volume 1.
II.Vital capacity 1.
III.Inspiratory reserve
volume
IV.Inspiratory capacity 4600 mL
Which one of the following is the correct matching of two capacities and volumes?
a) II 3000 mL, III 4600 mL b) III 1200 mL, IV 3000 mL
c) IV 3500 mL, I 1200 mL d) I 4600 mL, II 3500 mL
Exchange of gases in lungs occurs through
a) Simple diffusion b) Active transport c) Osmosis d) Plasmolysis
Partial Blood Blood Tissues
pressure (De oxy (Oxyge
Of Gases genated) nated)
O2 40 B 40
CO2 A 40 C
Choose the correct option for A, B and C to complete the given data
a) A-40, B-95, C-40
b) A-45, B-95, C-45
c) A-35, B-95, C-45
d) A-35, B-95, C-95
Floating ribs of thoracic cage are
a) 1st to 7th pair b) 8th to 9th pair c) 8th to 10th pair d) 11th to 12th pair
At which thoracic vertebra does trachea divide into right and left primary bronchi?
a) 5 b) 6 c) 9 d) 4
The partial pressure of oxygen in the alveolar air is
a) 45 mm Hg b) 95 mm Hg c) 104 mm Hg d) 110 mm Hg
Inspiration is initiated by
a) Extension of the diaphragm b) Contraction of the diaphragm
c) Extension of the lungs d) Contraction of the lungs
Why do human beings face difficulty to breath in high elevations?

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a) Lower % of O2 b) Temperature lower c) High pressure d) Low 𝜌O2

During normal respiration without any effort the volume of air inspired or expired is called
a) Tidal volume b) Reserve volume c) Residual volume d) None of these
Identify the different parts of the respiratory system in accordance to their location given below
I. Posterior part of the pharynx
II. Present at the glottis
III. In front of oesophagus
Choose the correct option accordingly
a) I-Nasal cavity, II-Larynx, III-Bronchi b) I-Nasopharynx, II-Epiglottis, III-Wind pipe
c) I-Glottis, II-Larynx, III-Trachea d) I-Larynx, II-Epiglottis, III-Trachea
The respiratory membranes facilitates the exchange of respiratory gases through diffusion. Oxygen enters
the deoxygenated blood through diffusion because
a) Partial pressure of oxygen in alveolar air and capillaries is 40 mm Hg and 100 mm Hg respectively
b) Partial pressure of oxygen in alveolar air and capillaries is 100 mm Hg and 40 mm Hg respectively
c) Partial pressure of oxygen in alveolar air and capillaries is 46 mm Hg and 40 mm Hg respectively
d) Partial pressure of oxygen in alveolar air and capillaries is 40 mm Hg and 46 mm Hg respectively
Which of the following gas is quite insignificant for the regulation of respiration rhythm?
a) SO2 b) N2 c) CO d) O2
What is vital capacity of our lungs?
a) Inspiratory reserve volume plus tidal volume
b) Total lung capacity minus expiratory reserve volume
c) Inspiratory reserve volume plus expiratory reserve volume
d) Total lung capacity minus residual volume
Which of the following statements is not true?
a) The partial pressure of oxygen in deoxygenated blood is 40 mm Hg
b) The partial pressure of oxygen in oxygenated blood is 95 mm Hg
c) The partial pressure of oxygen in the alveolar air is 104 mm Hg
d) The partial pressure of carbon dioxide in deoxygenated blood is 95 mm Hg
Respiratory Gas Atmospheric Air Alveoli
O2 159 A
CO2 0.3 B
Partial pressure (in mm Hg) of oxygen and carbon dioxide at different part involved in diffusion in
comparison to those in atmosphere. Identify A and B and choose the correct option accordingly
a) A-50; B-50 b) A-104; B-40 c) A-40; B-104 d) A-101; B-104
When the oxygen supply to the tissue is inadequate, the condition is
a) Dyspnea b) Hypoxia c) Asphyxia d) Apnea
Which two of the following changes (I-IV) usually tend to occur in the plain dwellers when they move to
high altitudes (3,500 m or more)?
I. Increase in red blood cell size.
II. Increase in red blood cell production.
III. Increased breathing rate.
IV. Increase in thrombocyte count.
Changes occurring are
a) I and III b) III and IV c) I and IV d) I and II
Arrange the following in the order of increasing volume
I.Tidal volume
II.Residual volume
III.Expiratory reserve volume
IV.Vital capacity
a) I < II < III < IV b) I < III < II < IV c) I < IV < III < II d) I < IV < II < III

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Chloride shift occurs in response to
a) HCO3 − b) K+ c) H+ d) Na+
Which situation would result in the greatest degree of O2 situation for haemoglobin, if 𝓅O2 remains
constant?
a) Increased CO2 level, decreased temperature
b) Decreased CO2 level, decreased temperature
c) Increased CO2 level, increased temperature
d) Decreased CO2 level, increased temperature
Blood do not become acidic although it carries CO2 because
a) CO2 is continuously diffused though tissues b) CO2 combines with H2O to form H2CO3
c) In CO2 transport, buffers plays an important role d) CO2 is absorbed by WBC
On high mountains difficulty in breathing is due to
a) Decrease in partial pressure of oxygen b) Decrease in amount of oxygen
c) Increase in carbon dioxide concentration d) All of the above
What is Bohr’s effect?
a) Raise of pCO2 or fall in pH decreases the oxygen affinity of haemoglobin
b) Decrease of pCO2 or fall in pH decreases the oxygen affinity of haemoglobin
c) Raise of pCO2 or increase in pH decreases the oxygen affinity of haemoglobin
d) Shifting of the oxygen-haemoglobin curve to left
One of the major cause of emphysema is
a) Pollution b) Smog c) Cigarette smoking d) Sanitary condition
Animals who use their skin as an accessory respiratory organ are
I. lizard II. frog
III. rabbit IV. Zebra
Choose the correct option
a) I and II b) Only I c) IV and II d) Only II
When the oxygen supply to the tissues is inadequate, the condition is
a) Hypoxia b) Asphyxia c) Pleuracy d) Anoxia
The percentage of oxygen in inhaled air is about
a) 21% b) 16% c) 79% d) 4%
State wheather the given statements are true or false
I. Respiration in humans is an active process
II. Diaphragm helps in generating the pressure gradient in the lungs
Choose the correct option
a) I – True, II – False b) I – True, II – True c) I – False, II – True d) I – False, II – False
When carbon dioxide concentration in blood increases, breathing becomes
a) Shallower and slow b) There is no effect on breathing
c) Slow and deep d) Faster and deeper
I. Intra pulmonary pressure remains less than the atmospheric pressure
II. There is negative pressure in the lungs than the atmospheric pressure
In which of the above two situations inspiration takes place?
Choose the correct option accordingly?
a) Only I b) Only II c) Both I and II d) I or II
Under which condition, dissociation of oxygen from oxyhaemoglobin in tissues occurs?
a) Low 𝜌O2 b) High 𝜌CO2 c) High H+ d) All of these
In the given diagram, identify what is depicted by 𝐴,𝐵 and 𝐶
Choose the correct option

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a) A-Air going out from lungs, B-Ribs and sternum relaxed, C-Volume of thorax increased
b) A-Air entering lungs, B-Ribs and sternum relaxed, C-Volume of thorax increased
c) A-Air entering lungs, B-Ribs and sternum raised, C-Volume of thorax increased
d) A-Air going out from lungs, B-Ribs and sternum relaxed, C-Volume of thorax decreased

Which of the following statement is false?
a) The conducting part of the respiratory system transports the atmospheric air to alveoli
b) Conducting part of the respiratory system clears the air from foreign particles, humidifies and brings it
to the body temperature
c) Exchange part of the respiratory system is the actual site at which O2 and CO2 exchange takes place
d) None of the above
Lungs comprises
a) Network of bronchi b) Bronchioles c) Alveoli d) All of these
Which of the following statement is incorrect about nasopharynx?
a) Internal nostrils opens into nasopharynx
b) It is the common passage for air only
c) It is a portion of pharynx
d) Nasopharynx opens through the glottis of the larynx region into the trachea
Pneumonia is an infection of
a) Trachea b) Larynx c) Vocal cord d) Lungs
Which of the following equation is correct?

a) b)

c)

d)

Site of aerobic respiration in higher organisms is/are
a) Golgi apparatus b) Mitochondria c) Both (a) and (b) d) Lungs
The total thickness of the diffusion membrane of alveolus capillary is
a) Less than 1 cm b) Less than 2 cm c) Less than 1 mm d) More than 1 mm
During expiration, the diaphragm becomes
a) Dome-shaped b) Oblique c) Normal d) Flattened
Which fact suggests that most oxygen is transported from lungs to the tissues combined with haemoglobin
rather than dissolved in blood plasma?
a) Oxygen carrying capacity of whole blood is much higher than that of plasma and oxygen content of
blood leaving the lungs is greater than that of blood entering the lungs
b) Haemoglobin can combine with oxygen
c) Oxyhaemoglobin can dissociate into haemoglobin and oxygen
d) Increase in carbon dioxide concentration decreases the oxygen affinity of haemoglobin

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A large proportion of oxygen is left unused in the human blood even after its uptake by the body tissues.
This O2
a) Raises the 𝑝CO2
of blood to 75 mm of Hg
b) Is enough to keep oxyhaemoglobin
c) Helps in releasing more O2 to the epithelial tissues
d) Acts as a reserve during muscular exercises
Which of the following statement is true regarding the human respiratory system?
a) Tracheal rings are of hyaline cartilage
b) Dorsal side of the thoracic chamber is formed by sternum
c) Expiration occurs when there is negative pressure in the lungs
d) Inspiration occurs when there is positive pressure in the lungs
When the nutrients are oxidised without using molecular O2 called …A… in yearst glucose formed …B…
and CO2. Endoparasite also respire …C… . It gives low energy.
Choose the correct option for A, B and C
a) A-fermentation, R-ethyl alcohol, C-anaerobically
b) A-fermentation, B-methyl alcohol, C-anaerobically
c) A-fermentation, B-alcohol, C-aerobically
d) A-fermentation, B-ethyl alcohol, C-aerobically
The ventilation movements of the lungs in mammals is governed by
a) Diaphragm b) Coastal muscles c) Both (a) and (b) d) None of these
CO2 diffuses into …A… and forms HCO3 − and H+. At the …B… site where pCO2 is low, the reaction proceeds
in the opposite direction.
Thus, CO2 is trapped as …C… at the tissue level and transported to alveoli is released out as …D…
Select the right choice for A, B, C and D to complete the given NCERT statement
a) A-WBC, B-diffusion, C-carbonate, D-O2 b) A-RBC, B-alveolar, C-bicarbonate, D-CO2
c) A-RBC, B-alveolar, C-bicarbonate, D-O2 d) A-RBC, B-alveolar, C-carbonate, D-CO2
Lungs have a large number of narrow tubes called
a) Alveoli b) Bronchi c) Bronchioles d) Tracheae
Conducting part of the respiratory system comprises
a) External nostrils upto the terminal bronchioles b) Internal nostrils upto trachea
c) Epiglottis upto trachea d) Larynx upto bronchi
Arrange the given steps of respiration mechanism in the order, they occur in the human body
I. Breathing or pulmonary ventilation
II. Diffusion across the alveolar membrane
III. Transport of gases by blood
IV. Utilisation of O2 by cells
V. Diffusion of O2 and CO2 between blood and tissues
Choose the correct option
a) I → II → III → IV → V b) I → II → III → V → IV c) I → III → II → V → IV d) I → III → II → IV → V
How many layers are present in the diffusion membrane of alveolus capillary?
a) 5 b) 3 c) 2 d) 4
Blood analysis of a patient reveals an unusually high quantity of carboxyhaemoglobin content. Which of
the following conclusions is most likely to be correct?
a) Carbon disulphide the patient has been inhaling polluted air containing usually high content of
b) Chloroform the patient has been inhaling polluted air containing usually high content of
c) Carbon dioxide the patient has been inhaling polluted air containing usually high content of
d) Carbon monoxide the patient has been inhaling polluted air containing usually high content of
What happens in Hamburger shift?
a) HCO3 − ions move out from plasma and Cl− ions enters into RBC
b) CO3 − ions move out from plasma and Cl− ions enters into RBC

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NEET Biology MCQs Breathing and Exchange Of Gases

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