NEET Biology Breathing and Exchange of Gases MCQs Set 07

Multiple Choice Questions (MCQs) for NEET Biology: Breathing and Exchange of Gases

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Multiple Choice Questions

Question 1: A specialised centre known as respiratory rhythm centre regulates respiration. It is located in
(a) Pons
(b) Medulla oblongata
(c) Cerebrum
(d) Cerebellum
Show Answer & Explanation

Answer: (b) Medulla oblongata

Explanation:
1. Respiratory rhythm centre are present in medulla which regulates the normal rhythm of respiration.

Question 2: Which substances when present in high level can activate the chemosensitive area present adjacent to rhythm centre?
(a) CO2 and O2
(b) HCO3– ions and O2
(c) CO2 and H+ ions
(d) H+ and HCO3– ions
Show Answer & Explanation

Answer: (c) CO2 and H+ ions

Explanation:
1. Chemosensitive area i.e. sensitive for chemicals and is located adjacent to the rhythm centre which contains chemoreceptors which are sensitive for CO2 and H+ ions.
2. The respiratory centre is stimulated by concentration or partial pressure of CO2 and H+ ions in blood and body fluids.

Question 3: Which of the following is an occupational respiratory disease?
(a) Diphtheria
(b) Pneumonia
(c) Tuberculosis
(d) Asbestosis
Show Answer & Explanation

Answer: (d) Asbestosis

Explanation:
1. Occupational respiratory disorders occur due to the continuous exposure to harmful substances, gases, fumes and dust in the environment, where a person works.
2. Asbestosis caused due to continuonus exposure to asbestos dust at place of work.
3. Pneumonia : Caused due to the bacteria like Streptococcus pneumoniae and haemophilus influenzae.
4. Tuberculosis : Caused due to Mycobacterium tuberculosis.

Question 4: Which group of animals respire through lungs?
(a) Earthworm and insects
(b) Sponges, coelenterates and flatworms
(c) Fishes and aquatic arthropods
(d) Reptiles, birds and mammals
Show Answer & Explanation

Answer: (d) Reptiles, birds and mammals

Explanation:
1. (i) Earthworm → Respires through moist cuticle (ii) Insects (Cockroach) → Tracheal system (iii) Sponges No well-developed respiratory organ (iv) Coelenterates is present.
2. Exchange of gases occurs (v) Flatworms by simple diffusion. (vi) Fish Gills (vii) Aquatic arthropod (viii) Reptiles (ix) Birds Lungs (x) Mammals.

Question 5: Skin of man cannot act as respiratory organ because
(a) It is dry
(b) It is not thin
(c) It is not permeable to O2 and CO2
(d) All of these
Show Answer & Explanation

Answer: (d) All of these

Explanation:
1. This is so because human skin is dry (does not allow exchange of gases), it is not thin (gases can pass through thin membrane) and it is impermeable to O2 and CO2).

Question 6: Ventrally and laterally, the thoracic chamber is formed by
(a) Diaphragm and sternum respectively
(b) Ribs and sternum respectively
(c) Sternum and ribs respectively
(d) Vertebral column and diaphragm respectively
Show Answer & Explanation

Answer: (c) Sternum and ribs respectively

Explanation:
1. Thoracic cavity is formed : Dorsally – By the vertebral column Ventrally – By the sterum Laterally – By the ribs.

Question 7: Adam's apple is another name for
(a) Sound box in birds
(b) Sound box in man
(c) Epiglottis
(d) Thyroid cartilage
Show Answer & Explanation

Answer: (d) Thyroid cartilage

Explanation:
1. Its shape is like apple.
2. It is hyaline cartilage and more prominent in male.

Question 8: Ring like cartilage of larynx is known as
(a) Thyroid cartilage
(b) Arytenoid cartilage
(c) Cricoid cartilage
(d) Cartilage of Santorini
Show Answer & Explanation

Answer: (c) Cricoid cartilage

Explanation:
1. Cricoid cartilage has signet ring-like structure lie below the thyroid cartilage and it is made up of hyaline cartilage.

Question 9: Which of the following prevents collapsing of trachea?
(a) Muscles
(b) Diaphragm
(c) Ribs
(d) Cartilaginous rings
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Answer: (d) Cartilaginous rings

Explanation:
1. Trachea is lined by C-shaped cartilagenous ring, which prevents the collapsing of trachea.

Question 10: In human, oblique fissure is present in
(a) Right lung
(b) Left lung
(c) Both of these
(d) None of these
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Answer: (c) Both of these

Explanation:
1. Both right and left lungs have oblique fissure whereas only right lung also has a horizontal fissure.

Question 11: During inspiration, the volume of thoracic cavity increases because of
(a) Contraction of diaphragm and external intercostal muscles
(b) Relaxation of diaphragm and external intercostal muscles
(c) Contraction of diaphragm and relaxation of external intercostal muscles
(d) Relaxation of diaphragm and contraction of external intercostal muscles
Show Answer & Explanation

Answer: (a) Contraction of diaphragm and external intercostal muscles

Explanation:
1. During inspiration, the contraction of diaphragm muscle causes it to become flat and lowered down, thereby increasing the volume of thoracic cavity in antero-posterior axis.
2. The contraction of external intercostal muscle, lift ribs and sternum up and outward causing an increase in volume of thoracic cavity in the dorso-ventral axis i.e., backward-forward direction.

Question 12: Volume of thoracic chamber increases in antero-posterior and dorso-ventral axis in rabbit by
(a) Contraction of diaphragm and external intercostal muscles respectively
(b) Relaxation of diaphragm and external intercostal muscles respectively
(c) Relaxation of diaphragm and abdominal muscles respectively
(d) Contraction of abdominal muscles and relaxation of external intercostal muscles respectively
Show Answer & Explanation

Answer: (a) Contraction of diaphragm and external intercostal muscles respectively

Explanation:
1. During inspiration, the contraction of diaphragm muscle causes it to become flat and lowered down, thereby increasing the volume of thoracic cavity in antero-posterior axis.
2. The contraction of external intercostal muscle, lift ribs and sternum up and outward causing an increases in volume of thoracic cavity in the dorso-ventral axis i.e., backward-forward direction.

Question 13: Expiration occurs due to
(a) Relaxation of diaphragm and external intercostal muscle
(b) Contraction of internal intercostal muscles and diaphragm
(c) Relaxation of abdominal and internal intercostal muscles
(d) Contraction of diaphragm and relaxation of abdominal muscles
Show Answer & Explanation

Answer: (a) Relaxation of diaphragm and external intercostal muscle

Explanation:
1. Expiration : It is the moving of air out of lungs if the pressure within the lungs is more than the atmospheric pressure.
2. Relaxation of the diaphragm and the external intercostal muscle returns the diaphragm and sternum to their normal thoracic volume and thereby pulmonary volume.

Question 14: What happens to the volume of pulmonary cavity when there is an increase in the volume of thoracic chamber?
(a) It decreases
(b) It increases
(c) It remains same
(d) First decreases and then increases
Show Answer & Explanation

Answer: (b) It increases

Explanation:
1. Increase in the volume of thoracic cavity Leads to Similar increase in the volume of pulmonary cavity Causes Decrease in pressure within the pulmonary cavity Causes Air enters from atmosphere to the lungs as it moves from higher pressure to lower pressure.

Question 15: What happens when pressure within the pulmonary cavity is higher than the atmospheric pressure?
(a) Inhalation of air
(b) Expulsion of air
(c) No inhalation and expulsion of air occurs
(d) Lungs inflate and rupture
Show Answer & Explanation

Answer: (b) Expulsion of air

Explanation:
1. High pressure in pulmonary cavity compared to atmosphere results in explusion of air.
2. Air moves high pressure to low pressure.

Question 16: An additional volume of air, a person can inspire by a forceful inspiration is known as
(a) Inspiratory capacity
(b) Expiratory capacity
(c) Expiratory reserve volume
(d) Inspiratory reserve volume
Show Answer & Explanation

Answer: (d) Inspiratory reserve volume

Explanation:
1. IRV is the additional volume of air a person can inspire by a forceful inspiration.
2. IRV = 2500 – 300 ml IC = IRV + TV 3000 – 3500 ml.

Question 17: Volume of air remains in the lungs after normal expiration is
(a) ERV + RV
(b) IRV + RV
(c) RV + IRV + ERV
(d) TV
Show Answer & Explanation

Answer: (a) ERV + RV

Explanation:
1. Volume of air remains in the lungs after normal expiration is known as functional residual capacity (FRC).
2. FRC = ERV + RV = 2500 ml.

Question 18: Solubility of CO2 is ______ times higher than that of O2
(a) 40 - 45
(b) 20 - 25
(c) 100 - 200
(d) 200 - 300
Show Answer & Explanation

Answer: (b) 20 - 25

Explanation:
1. CO2 : O2 (Solubility of CO2 : O2) 25 : 1.

Question 19: What are the characteristics of alveoli?
(a) Very thin, irregular walled and highly vascularised
(b) Thick and smooth membrane
(c) Network of blood capillaries and thick-walled
(d) Thick, regular walled and lack of blood vessels
Show Answer & Explanation

Answer: (a) Very thin, irregular walled and highly vascularised

Explanation:
1. Alveoli membrane is very thin, irregular, richly supplied with blood vessels because of which exchange of gases easily occurs here.

Question 20: What is the value of pO2 in alveoli and tissues respectively?
(a) 104 mm Hg and 150 mm Hg
(b) 45 mm Hg and 0.3 mm Hg
(c) 104 mm Hg and 40 mm Hg
(d) 95 mm Hg and 159 mm Hg
Show Answer & Explanation

Answer: (c) 104 mm Hg and 40 mm Hg

Explanation:
1. Respiratory gas Atmospheric air Alveoli Blood Blood Tissue (oxygenated) (Deoxygenated) O2 159 104 40 95 40 CO2 0.3 40 45 40 45.

Question 21: Which are the three main layers that form the diffusion membrane?
(a) Thin squamous epithelium of alveoli, basement membrane of bronchioles and basement substance
(b) Thin squamous epithelium of alveoli, endothelium of alveolar capillaries and the basement substance
(c) Basement substance, cuboidal epithelium of alveoli and stratified epithelium of bronchiole
(d) Ciliated epithelium of trachea, endothelium of capillaries and basement substance
Show Answer & Explanation

Answer: (b) Thin squamous epithelium of alveoli, endothelium of alveolar capillaries and the basement substance

Explanation:
1. Diffusion of O2 and CO2 depends on the thickness of diffusion membrane.

Question 22: Which of the following is not a character of respiratory surface?
(a) Thin, permeable to gases
(b) Extensive
(c) Least vascular
(d) Moist
Show Answer & Explanation

Answer: (c) Least vascular

Explanation:
1. Respiratory surface should be highly vascular for the easy transport of gases or exchange of gases with the blood.

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