CBSE Questions for Class 11 Medical Biology Breathing And Exchange Of Gases Quiz 10 - MCQExams.com

Even when there is no air in it, human trachea does not collapse due to the presence of:
  • cartilaginous rings
  • chitinous rings
  • bony rings
  • turgid pressure
Alveoli increase the surface area of the human lung which is approximately the size of a:
  • tennis court
  • dining table
  • dinner plate
  • small bowl
Choose the correct answer from the alternatives given.
Which of the following constitutes the wind pipe, or the upper four inches of the airway?
  • Trachea
  • Pharynx
  • Larynx
  • Bronchi
Choose the correct answer from the alternatives given.
The structure which does not contribute to breathing movements in mammals is
  • ribs
  • diaphragm
  • larynx
  • abdominal muscles
Choose the correct answer from the alternatives given.
What are the two large branches of the airway which lead off the trachea at the tracheal bifurcation?
  • Alveoli
  • Bronchi
  • Metavenules
  • Bronchioles
Choose the correct answer from the alternatives given.
The Adams apple is formed predominantly, by which of the following structures?
  • Larynx
  • Pharynx
  • Oesophagus
  • Bronchi
Choose the correct answer from the alternatives given.
In human lungs, gas exchange occurs at the
  • two bronchi
  • alveolar sacs
  • pleural sacs
  • both (b) and (c)
Choose the correct answer from the alternatives given.
Simple squamous non-ciliated epithelium is found in
  • alveoli
  • bronchi
  • bronchioles
  • trachea
Choose the correct answer from the alternatives given.
Which of the following is the cartilaginous structure that folds down to meet the uprising larynx to close off the airway during swallowing?
  • Trachea
  • Epiglottis
  • Cricoid cartilage
  • Thyroid cartilage
Choose the correct answer from the alternatives given.
The is an airway that connects the nose and mouth with the
  • Oral cavity; larynx
  • Trachea; pharynx
  • Pharynx; trachea
  • Pharynx; larynx
Choose the correct answer from the alternatives given.
In the nostril the air is
  • warned
  • filtered
  • moistened
  • all of these
State whether the following statements are true or false.
Gas exchanges continue uninterrupted in lungs even after a forceful expiration.
  • True
  • False
The release of oxygen by haemoglobin for use in body tissues is dependent on all of the following
  • low $$PO_2$$ of body tissue cells
  • alkaline pH of blood in tissue capillaries
  • presence of ATP
  • all of the above cause the release of oxygen from haemoglobin
Choose the correct answer from the alternatives given.
The amount of air that enters lungs during normal respiration is
  • tidal volume
  • vital capacity
  • total lung capacity
  • inspiratory capacity
In negative pressure breathing, inhalation results from:
  • forcing air from the throat down into the lungs
  • contracting the diaphragm
  • relaxing the muscles of the rib cage
  • contracting the abdominal muscles
State whether the following statements are true or false.
Lungs are completely emptied and refilled with fresh air during breathing.
  • True
  • False
The toxic effect of carbon monoxide is due to its greater affinity for haemoglobin as compared to oxygen approximately by
  • 200 times
  • 1000 times
  • 2 times
  • 20 times.
Which of the following reactions prevails in red blood cells travelling through pulmonary capillaries?
  • $$Hb \, + \, 4O_2 \, \rightarrow \, Hb(O_2)_4$$
  • $$Hb(O_2)_4 \, \rightarrow \, Hb \, + \, 4O_2$$
  • $$H_2CO_3 \, \rightarrow \, H^+ \, + \, HCO^-_3$$
  • $$Hb \, + \, (CO_2)_4 \, \rightarrow \, Hb(CO_2)_4$$
Select the correct sequence of events that occur during the delivery of $$O_2$$ from blood to tissue.

P: Absorption of $$CO_2$$ by the blood.
Q : Reaction of absorbed $$CO_2$$ with $$H_2$$ to form $$H_2 {CO}{_3}$$ within RBC and its conversion into $$H^+$$ and $${HCO}^{-}_{3}$$ ions.
R  : Reaction of absorbed $${CO}_2$$ with $$H_2{O}$$ in plasma to form $$H_2 {CO}{_3}$$ and its conversion into $$H^+$$ and $${HCO}^{-}_{3}$$ ions.
S:   Combination of $$H^+$$, $${CO}_2$$, and $${HbO}{_2}$$ to release $$O_2$$.
T:  Combination of $${HCO}^{-}_{3}$$ with heme portion of $${HbO}{_2}$$ to form reduced haemoglobin and release of $$O_2$$.
  • P, Q, T
  • P, R, S
  • P, Q, S
  • P, R, T

Given below is a sigmoid curve for oxyhemoglobin dissociation :-
Which of the following factor favour for shifting of curve (B) $$\leftarrow$$ (A)
878412_44f944461e5e417095a4f90e7a585d7b.png
  • Low $$PO_2$$, less $$H^+$$ concentration, less temperature.
  • High $$PO_2$$, less $$H^+$$ concentration, less temperature.
  • Low $$PO_2$$, less $$H^+$$ concentration, more temperature.
  • None of these
What will happen when a person stop his breathing only for few seconds ?
  • Concentration of $$CO_{2}$$ and $$H^{+}$$ increased in atrial blood.
  • Chemosensitive area situated adjacent to rhythm centre gets activated.
  • Oxygen dissociation curve shift towards right.
  • All are correct
When temperature decreases, oxy-Hb curve becomes.
  • More steep
  • Straight
  • Parabola
  • None of these
Amount of $${CO}_{2}$$ delivered by every 100 ml of deoxygenated blood is
  • 7 ml
  • 5 ml
  • 4 ml
  • 27 ml
Which of the following is an occupational respiratory disorder?
  • Botulism
  • Anthracis
  • Emphysema
  • Silicosis
Mammalian lungs have an enormous number of minute alveoli (air sac);This is to allow
  • more surface area for diffusion of gases
  • more space for increasing the volume of inspired air
  • more nerve supply to keep the lungs working
  • more spongy texture for keeping lung in proper shape.
Fill up the blanks in the following paragraph by selecting the correct option.
The movement of air into and out of the lungs is carried out by creating a ____(i)____ between the lungs and the atmosphere. Inspiration can occur if intra-pulmonary pressure is ___(ii)____than the atmospheric pressure. Expiration takes place when the intra-pulmonary pressure is ___(iii)___ than the atmospheric pressure. Inspiration is initiated by the ___(iv)___ of diaphragm which ____(v)____ the volume of thoracic chamber in the anteroposterior axis.
  • (i) concentration gradient (ii) less (iii) higher (iv) relaxation (v)increases
  • (i) concentration gradient (ii) higher (iii) less (iv) contraction (v)decreases
  • (i) pressure gradient (ii) higher (iii) less (iv) relaxation (v)decreases
  • (i) pressure gradient (ii) less (iii) higher (iv) contraction (v) increases
During expiration the diaphragm becomes
  • dome-shaped
  • oblique
  • concave
  • flattened.
The given diagram shows a blood capillary in close contact with structure Y. The relative concentration (in units) of carbon dioxide ($$CO_2$$) and oxygen ($$O_2$$) are given at three different sites.
Which of the following statements is correct?
887634_ff028e82994d421baade0ca29b1f3e12.JPG
  • Y is an alveolus and blood flow is from X to Z.
  • Y is an alveolus and blood flow is from Z to X.
  • Y is a muscle and blood flow is from X to Z.
  • Y is a muscle and blood flow is from Z to X.
Consider the following statements each with one or two blanks.
(i)    Left lung has ____(1)___ lobes and right lung has ___(2)___ lobes.
(ii)   Prawn respires with _(3)_ and insects with ___(4)___.
(iii) Amount of air inhaled and exhaled with maximum effort is referred to as the _(5)_ of the lungs.
Fill up the above blanks by selecting the correct option.
  • (1) - three, (2) - two, (3) - gills (4)-tracheae
  • (1) - two, (2) - three, (5) - vital capacity
  • (3) - gills, (4) - tracheae, (5) - tidal volume
  • (3) - tracheae, (4) - gills, (5) - tidal volume
Pick the correct statement.
  • The contraction of internal intercostal muscles lifts up the ribs and sternum.
  • The thoracic cavity is anatomically an air tight chamber.
  • Healthy man can inspire approximately $$500$$ ml of air per minute.
  • During expiration, the intrapulmonary pressure is slightly below the surrounding atmospheric pressure.
Lungs are enclosed in
  • Perichondrium
  • Pericardium
  • Pleural membrane
  • Peritoneum
Which one of the following statements is incorrect?
  • The principle of countercurrent flow facilitates efficient respiration m gilis of fishes.
  • The residual air in lungs slightly decreases the efficiency of respiration in mammals.
  • The presence of non-respiratory air sacs, increases the efficiency of respiration in birds.
  • In insects, circulating body fluids serve to distribute oxygen to tissues.
According to Boyle's law, the product of:.pressure and volume is a constant. Hence,
  • if volume of lungs is increased, then pressure decreases proportionately
  • if volume of lungs is increased, then pressure also increases proportionately
  • if volume of lungs is increased, then pressure decreases disproportionately
  • if volume of lungs is increased, then pressure remains the same.
Which of the following options is incorrect about the larynx (sound box)?
  • It is a bony box.
  • Glottis is the opening into the larynx.
  • During swallowing of food glottis is covered by epiglottis to prevent food entry into the larynx.
  • All of these.
The carbon dioxide is transported via blood to lungs mostly
  • In combination with haemoglobin only.
  • Dissolved in blood plasma.
  • In the form of bicarbonates.
  • As carbaminohaemoglobin.
Vital capacity of lungs is
  • IRV + ERV
  • IRV + ERV + TV - RV
  • IRV + ERV + TV + RV
  • IRV + ERV + TV.
Direction: Refer to the given graph and select the correct options for the questions that follow.

Blood can combine with almost______of oxygen if the hemoglobin is 100 percent saturated.
888667_38d40f67a080414b9286382e128874f6.png
  • 18 mL
  • 15 mL
  • 20 mL
  • 10 mL
Consider the following statements each with two blanks. 
(i)    Actually, only about ___(1)___ml of air enters the lung alveoli for the exchange of gases.The remaining fills the respiratory passage and is termed ___(2)___.
(ii) The amount of air which one can inhale with maximum effort and also exhale with maximum effort is termed as ___(3)___ . It is about ___(4)___ in normal adult person.
(iii) During normal quiet breathing, on an average, approximately _(5)_ ml of air is inspired or expired by adult human male in each breath. It is termed as __(6)__ volume.
Which of the following options gives the correct fill ups for the respective blank numbers from (1) to (6) in the above statements?
  • (3)-vital capacity, (4)-4000 mL, (5)-500, (6)-tidal
  • (1)-100, (2)-residual volume, (3)-functional residual capacity, (4)-3000mL
  • (1)-350,(2)-dead space air, (5)-1000,(6)-inspiratory reserve
  • (1)-350, (2)-residual volume, (3)-vital capacity, (4)-4000 mL
After forceful inspiration, the amount of air that can be breathed out by maximum forced expiration is equal to:
  • Inspiratory Reserve Volume (IRV) + Expiratory Reserve Volume (ERV) + Tidal Volume (TV) + Residual Volume (RV)
  • IRV + RV + ERV
  • IRV + TV + ERV
  • TV + RV + ERV
The Oxygen dissociation curve is
  • Parabola
  • Slope
  • Sigmoid
  • Straight line
The given graph shows an oxygen dissociation curve for haemoglobin.
Where in the body will haemoglobin be saturated at the percentages shown at points 1,2 and 3 on the graph?
888574_1f7ced5d9c484c03b24dfae0b7a1e7bb.JPG
  • Left ventricle1Pulmonary vein2 Vena cava3
  • Left ventricle2Pulmonary vein1Vena cava3
  • Left ventricle2Pulmonary vein3Vena cava1
  • Left ventricle3Pulmonary vein2Vena cava1
Besides RBC, blood plasma also carries $$O_{2}$$ in solution.The percentage is ___________.
  • 3-9%
  • 1-2%
  • 3-6%
  • 2-3%
Which of the following statements is correct?
  • The contraction of internal intercostal muscles lifts up the ribs and sternum.
  • The RBCs transport oxygen only.
  • The thoracic cavity is anatomically an air tight chamber.
  • Healthy man can inspire approximately 500 mL of air per minute.
Which of the following is incorrect about the given graph?
888573_b4b35f9906134d21a7ad0e1b3bfcfa9d.png
  • The curve, is called oxygen dissociation curve.
  • The part 'A' represents percentage saturation of haemoglobin with oxygen.
  • The part 'B' represents partial pressure of carbon dioxide.
  • This curve is highly useful in studying the effect of factors like $$PCO_{2}$$, H+ concentration, etc. on binding of $$CO_{2}$$ with haemoglobin.
In humans, which of the following is not a step in respiration?
  • Alveolar diffusion of $$O_{2}$$ and $$CO_{2}$$
  • Transport of gases by blood
  • Diffusion of $$O_{2}$$ and $$CO_{2}$$ between blood and tissues
  • Utilisation of $$CO_{2}$$ by cells for catabolic reactions
Read the given statements and select the correct option. 

Statement 1: About 70% of $$CO_{2}$$ that enters RBCs changes into. $$HCO_3$$ for transport in plasma to the lungs where it reconverts into $$CO_{2}$$ for elimination.
Statement 2: About 40% of $$CO_{2}$$ that enters RBCs changes into carbaminohaemoglobin which releases $$O_{2}$$ in the lungs.
  • Both statements 1 and 2 are correct.
  • Statement 1 is correct but statement 2 is incorrect.
  • Statement 1 is incorrect but statement 2 is correct.
  • Both statements 1 and 2 are incorrect.
Direction: Refer to the given graph and select the correct options for the questions that follow.

Which of these is correct regarding D, E and F areas in the graph?
888671_163bb22d30b64c0d84efafa1d273baaf.png
  • D shows venous blood in exercise.
  • E shows normal venous blood.
  • F shows normal arterial blood.
  • All of the above
Carbon monoxide can kill a person because of it's extremely high affinity for
  • haemoglobin
  • phytochrome
  • cytochrome
  • none of these.
When temperature decreases, oxy-Hb curve becomes 
  • more steep
  • straight
  • parabola
  • none of these.
A large proportion of oxygen remains unused in the human blood even after its uptake by the body tissues. This $$O_{2}$$
  • acts as a reserve during muscular exercise
  • raises the $$PCO_{2}$$ of blood to 75 mm of Hg
  • is enough to keep oxyhaemoglobin saturation at 96%
  • helps in releasing more $$O_{2}$$ to the epithelial tissues.
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Practice Class 11 Medical Biology Quiz Questions and Answers