CBSE Class 11 Biology Breathing and Exchange of Gases MCQs Set B

Question. When about 1200 mL air is in the lungs after forceful expiration, it is called
a) residual volume
b) inspiratory reserve volume
c) vital capacity
d) tidal volume.

Answer : A

Question. 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
a) suffocation
b) asphyxia
c) emphysema
d) eupnea.

Answer : B

Question. After forceful inspiration, the amount of air that can be breathed out by maximum forced 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.

Answer : C

Question. Among mammals, the efficiency of ventilation of lungs as compared to reptiles and birds is better developed by the presence of
a) ribs and costal muscles
b) only ribs
c) only costal muscles
d) diaphragm.

Answer : D

Question. Pneumotaxic centre is present in
a) pons
b) medulla
c) cerebrum
d) lungs.

Answer : A

Question. In oxygen dissociation curve x-axis and y-axis represents.
a) x-axis—partial pressure of oxygen
y-axis—percentage saturation of Hb with oxygen
b) 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 haemoglobin
y-axis—partial pressure of oxygen
c) x-axis—partial pressure of CO₂
y - a x i s — percentagesaturation of oxyhaemoglobin with oxygen
d) x-axis—partial pressure of CO₂
y-axis—partial pressure of oxygen.

Answer : A

Question. Factor helps in formation of oxyhaemoglobin in alveoli is
a) high pCO₂
b) high pO₂
c) higher H+ concentration
d) all of these.

Answer : B

Question. Cartilaginous rings in trachea are incomplete at which surface?
a) Dorsal
b) Ventral
c) Lateral
d) Ventrolateral

Answer : A

Question. Between breaths the intrapleural pressure is approximately ___ mmHg less than atmospheric pressure.
a) 1
b) 4
c) 8
d) 10

Answer : B

Question. Oxyhaemoglobin is converted into haemoglobin during the internal respiration because
a) an enzyme splits oxyhaemoglobin
b) oxygen tension in tissue is less than capillary blood reaching tissue
c) CO2 tension is low in blood that reaches tissue
d) oxyhaemoglobin is unstable.

Answer : D

Question : Bulk of carbon dioxide (CO₂) released from body tissues into the blood is present as
a) bicarbonate in blood plasma and RBCs
b) 70% carbamino- haemoglobin and 30% as bicarbonate
c) carbamino-haemoglobin in RBCs
d) free CO2 in blood plasma

Answer : A

Question : A large proportion of oxygen is left unused in the human blood even after its uptake by the body tissues. This O₂
a) acts as a reserve during muscular exercise
b) is enough to keep oxyhaemoglobin saturation at 96%
c) helps in releasing more O₂ to the epithelial tissues
d) None of these

Answer : A

Question : The alveolar epithelium in the lung is
a) non-ciliated columnar
b) non-ciliated squamous
c) ciliated columnar
d) ciliated squamous
Answer : B

Question : Skin is an accessory organ of respiration in
a) human
b) frog
c) rabbit
d) lizard
Answer : B

Question : Carbon dioxide is transported from tissues to respiratory surface by only
a) plasma and erythrocytes
b) plasma
c) erythrocytes
d) erythrocytes and leucocytes
Answer : A

Question : Air is breathed through
a) trachea—lungs—larynx—pharynx—alveoli
b) nose—larynx—pharynx—bronchus—alveoli—bronchioles
c) nostrils—pharynx—larynx—trachea—bronchi—bronchioles—alveoli
d) nose — mouth — lungs
Answer : C

Question : Oxygen dissociation curve of haemoglobin is
a) sigmoid
b) hyperbolic
c) linear
d) hypobolic
Answer : A

Question : Although much CO₂ is carried in blood, yet blood does not become acidic, because
a) it is absorbed by the leucocytes
b) blood buffers play an important role in CO₂ transport
c) it combines with water to form H₂CO₃ which is neutralized by Na2CO3
d) it is continuously diffused through tissues and is not allowed to accumulate
Answer : B

Question : The carbon dioxide is transported via blood to lungs as
a) dissolved in blood plasma
b) in the form of carbonic acid only
c) in combination with haemoglobin only
d) carbaminohaemoglobin and as carbonic acid
Answer : D

Question : The quantity 1500 mL in the respiratory volumes of a normal human adult refers to
a) maximum air that can be breathed in and breathed out
b) residual volume
c) expiratory reserve volume
d) total lung capacity
Answer : B

Question : In alveoli of the lungs, the air at the site of gas exchange, is separated from the blood by
a) alveolar epithelium only
b) alveolar epithelium and capillary endothelium
c) alveolar epithelium, capillary endothelium and tunica adventitia
d) alveolar epithelium, capillary endothelium, a thin layer of tunica media and tunica adventitia
Answer : B

Question : The exchange of gases in the alveoli of the lungs takes place by
a) simple diffusion
b) osmosis
c) active transport
d) passive transport
Answer : A

Question : Which one of the following organs in the human body is most affected due to shortage of oxygen?
a) Intestine
b) Skin
c) Kidney
d) Brain
Answer : D

Question : The process of migration of chloride ions from plasma to RBC and of carbonate ions from RBC to plasma is
a) chloride shift
b) ionic shift
c) atomic shift
d) Na+ pump
Answer : A

Question : When CO₂ 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
Answer : D

Question : 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) The patient has been inhaling polluted air containing unusually high content of carbon disulphide
b) The patient has been inhaling polluted air containing unusually high content of chloroform
c) The patient has been inhaling polluted air containing unusually high content of carbon dioxide
d) The patient has been inhaling polluted air containing unusually high content of carbon monoxide
Answer : D

Question : 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
a) atmospheric O2 level is less and hence,more RBCs are needed to absorb the required amount of O2 to survive
b) there is more UV radiation which enhances RBC production
c) people eat more nutritive food, therefore, more RBCs are formed
d) people get pollution-free air to breathe and more oxygen is available
Answer : A

Question : What is the 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
Answer : D

Question : The haemoglobin of a human foetus
a) has a lower affinity for oxygen than that of the adult
b) its affinity for oxygen is the same as that of an adult
c) has only 2 protein subunits instead of 4
d) has a higher affinity for oxygen than that of an adult
Answer : D

Question : Which one of the following is a possibility for most of us in regard to breathing, by making a conscious effort ?
a) The lungs can be made fully empty by forcefully breathing out all air from them
b) One can breathe out air totally without oxygen.
c) One can breathe out air through eustachian tubes by closing both the nose and the mouth
d) One can consciously breath in and breath out by moving the diaphragm alone, without moving the ribs at all.
Answer : A

Question : A large proportion of oxygen is left unused in the human blood even after its uptake by the body tissues. This O₂
a) Acts as a reserve during muscular exercise
b) Raises the pCO₂ of blood to 75 mm of Hg.
c) Is enough to keep oxyhaemoglobin sturation at 96%
d) Helps in releasing more O₂ to the epithelial tissues
Answer : A

Question : 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
a) Epiglottis
b) Diaphragm
c) Neck
d) Tongue

Answer : A