NEET Biology Breathing and Exchange of Gases MCQs Set 08

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Multiple Choice Questions

Question 1: In mature mammalian erythrocytes, the respiration is
(a) Aerobic
(b) Anaerobic
(c) Sometimes aerobic and sometimes anaerobic
(d) Absent
Show Answer & Explanation

Answer: (b) Anaerobic

Explanation:
1. Mature RBCs do not have cell organelle (like mitochondria) and nucleus, so in mature RBC anaerobic respiration occurs.

Question 2: Pneumotaxic centre can moderate the functions of respiratory rhythm centre by
(a) Reducing the duration of inspiration
(b) Increasing the duration of inspiration only
(c) First increasing and then reducing the duration of expiration
(d) Increasing the duration of expiration only
Show Answer & Explanation

Answer: (a) Reducing the duration of inspiration

Explanation:
1. Pneuomotaxic centre is present in the pons region of hind brain.
2. It is also known as "switch off point of inspiration" i.e. it reduces the duration of inspiration and alter the respiratory rate and depth of breathing.

Question 3: A chronic disorder in which alveolar walls are damaged due to excessive cigarette smoking is
(a) Asthma
(b) Emphysema
(c) Silicosis
(d) Bronchitis
Show Answer & Explanation

Answer: (b) Emphysema

Explanation:
1. This is so because due to excessive cigarette smoking Emphysema Walls of alveoli get damaged and loss of elasticity of walls of bronchioles and alveoli Due to which, surface area for exchange of gases is reduced Asthma : Caused because of allergen and effects the respiratory tract.
2. Bronchitis : Inflammation of bronchi.
3. Silicosis : It is an occupational respiratory disorder caused due to continuous exposure of asbestos dust at place of work.

Question 4: Reduction in pH of blood will
(a) Release bicarbonate ions by the liver
(b) Reduce the rate of heart beat
(c) Reduce the blood supply to the brain
(d) Decrease the affinity of hemoglobin with oxygen
Show Answer & Explanation

Answer: (d) Decrease the affinity of hemoglobin with oxygen

Explanation:
1. Reduction in pH of blood favours the dissociation of oxyhemoglobin.

Question 5: Asthma may be attributed to
(a) Accumulation of fluid in the lungs
(b) Bacterial infection of the lungs
(c) Allergic reaction of the mast cells in the lungs
(d) Inflammation of the trachea
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Answer: (c) Allergic reaction of the mast cells in the lungs

Explanation:
1. Asthma is an allergic reaction characterised by spasm of bronchi muscles because of effect of histamine released by mast cells.

Question 6: When you hold your breath, which of the following gas changes in blood would first lead to the urge to breathe?
(a) Rising CO2 and falling O2 concentration
(b) Falling O2 concentration
(c) Rising CO2 concentration
(d) Falling CO2 concentration
Show Answer & Explanation

Answer: (c) Rising CO2 concentration

Explanation:
1. This option, Rising CO2 concentration, is the correct choice, as it agrees with the standard NCERT account of this topic.

Question 7: Approximately seventy percent of carbon-dioxide absorbed by the blood will be transported to the lungs
(a) As bicarbonate ions
(b) In the form of dissolved gas molecules
(c) By binding to R.B.C
(d) As carbamino - haemoglobin
Show Answer & Explanation

Answer: (a) As bicarbonate ions

Explanation:
1. Nearly 20 – 25 percent of CO2 is transported by RBCs, whereas, 70 percent of it is carried as bicarbonates.
2. About 7 percent of CO2 is carried as dissolved state in plasma.

Question 8: Which one of the following is the correct statement for respiration in humans?
(a) About 90% of carbon dioxide (CO2) is carried by haemoglobin as carbamino-haemoglobin
(b) Cigarette smoking may lead to inflammation of bronchi
(c) Neural signals from pneumotoxic centre in pons region of brain can increase the duration of inspiration
(d) Workers in grinding and stone-breaking industries may suffer, from lung fibrosis
Show Answer & Explanation

Answer: (d) Workers in grinding and stone-breaking industries may suffer, from lung fibrosis

Explanation:
1. Option (1) is wrong, because ~70% of CO2 is carried by haemoglobin as carbaminohaemoglobin.
2. Option (2) is wrong, because cigarette smoking lead to damage of alveoli wall.
3. Option (3) is wrong, because pneumotaxic centre in pons region of brain decrease the duration of inspiration.

Question 9: People who have migrated from the planes to an area adjoining Rohtang Pass about six months back
(a) Have the usual RBC count but their haemoglobin has very high binding affinity to O2
(b) Have more RBCs and their haemoglobin has a lower binding affinity of O2
(c) Are not physically fit to play games like football
(d) Suffer from altitude sickness with symptoms like nausea, fatigue, etc
Show Answer & Explanation

Answer: (b) Have more RBCs and their haemoglobin has a lower binding affinity of O2

Explanation:
1. High altitude (pO2 less) so more RBC production, which leads to polycythemia i.e., increased RBC count.

Question 10: A large proportion of oxygen is left unused in the human blood even after its uptake by the body tissues. This O2
(a) Helps in releasing more O2 to the epithelial tissues
(b) Acts as a reserve during muscular exercise
(c) Raises the pCO2 of blood to 75 mm of Hg.
(d) Is enough to keep oxyhaemoglobin saturation at 96%
Show Answer & Explanation

Answer: (b) Acts as a reserve during muscular exercise

Explanation:
1. This is so because during exercise, contraction of muscle occurs and for that more energy is required and for energy oxygen is required.

Question 11: Which one of the following is a possibility for most of us in regard to breathing, by making a conscious effort?
(a) One can consciously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all
(b) The lungs can be made fully empty by forcefully breathing out all air from them
(c) One can breathe out air totally without oxygen
(d) One can breathe out air through eustachian tubes by closing both the nose and the mouth
Show Answer & Explanation

Answer: (a) One can consciously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all

Explanation:
1. If we push voluntarily abdominal contents towards diaphragm, it will lead to expiration without involvement of intercostal muscle.

Question 12: What is vital capacity of our lungs?
(a) Total lungs capacity minus residual volume
(b) Inspiratory reserve volume plus tidal volume
(c) Total lungs capacity minus expiratory reserve volume
(d) Inspiratory reserve volume plus expiratory reserve volume
Show Answer & Explanation

Answer: (a) Total lungs capacity minus residual volume

Explanation:
1. Vital capacity is the maximum volume of air a person can breathe in after a forceful expiration.
2. Vital capacity (VC) = Total lung capacity – Residual volume.

Question 13: People living at sea level have around 5 million RBC per cubic millimeter of their blood whereas those living at an altitude of 5400 metres have around 8 million. This is because at high altitude
(a) People get pollution-free air to breathe and more oxygen is available
(b) Atmospheric O2 level is less and hence more RBCs are needed to absorb the required amount of O2 to survive
(c) There is more UV radiation which enhances RBC production
(d) People eat more nutritive food, therefore more RBCs are formed
Show Answer & Explanation

Answer: (b) Atmospheric O2 level is less and hence more RBCs are needed to absorb the required amount of O2 to survive

Explanation:
1. This option, Atmospheric O2 level is less and hence more RBCs are needed to absorb the required amount of O2 to survive, is the correct choice, as it agrees with the standard NCERT account of this topic.

Question 14: Which one of the following statements is incorrect?
(a) The residual air in lungs slightly decreases the efficiency of respiration in mammals
(b) The presence of non-respiratory air sacs, increases the efficiency of respiration in birds
(c) In insects, circulating body fluids serve to distribute oxygen to tissues
(d) The principle of countercurrent flow facilitates efficient respiration in gills of fishes
Show Answer & Explanation

Answer: (c) In insects, circulating body fluids serve to distribute oxygen to tissues

Explanation:
1. In insects tracheal system serve to distribute oxygen to tissues.
2. Openings of trachae are called spiracles and present for entry and exist of gases.

Question 15: The majority of carbon dioxide produced by our body cells is transported to the lungs
(a) Dissolved in the blood
(b) As bicarbonates
(c) As carbonates
(d) Attached to haemoglobin
Show Answer & Explanation

Answer: (b) As bicarbonates

Explanation:
1. This option, As bicarbonates, is the correct choice, as it agrees with the standard NCERT account of this topic.

Question 16: In man and other mammals, air passes from outside into the lungs through
(a) Nasal cavity, larynx, pharynx, trachea, bronchi, alveoli
(b) Nasal cavity, larynx, pharynx, trachea, bronchioles, alveoli
(c) Nasal cavity, pharynx, larynx, trachea, bronchioles, bronchi, alveoli
(d) Nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli
Show Answer & Explanation

Answer: (d) Nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli

Explanation:
1. External nostils Respiratory passage : Nasal chamber Internal nares Nasopharynx Conducting part Larynx Trachea Bronchi Bronchioles Alveolar duct Respiratory/Exchange part Alveoli.

Question 17: Lungs are enclosed in
(a) Peritoneum
(b) Perichondrium
(c) Pericardium
(d) Pleural membranes
Show Answer & Explanation

Answer: (d) Pleural membranes

Explanation:
1. Lungs are enclosed in pleural membranes. i.e. external pleura and internal pleura and in between pleural fluid is present.
2. Pericardium → Membrane covers the heart Perichondrium → Outer covering of cartilage Peritoneum → Covering of visceral organ.

Question 18: When a person breathes air through a tube directly into the trachea (tracheotomy) it may lead to serious lung crushing and infection due to
(a) Cooling effect
(b) Drying effect
(c) Non filtering effect
(d) All of these
Show Answer & Explanation

Answer: (d) All of these

Explanation:
1. This is so because upper respiratory tract helps in filtering the air, bringing air to body temperature and making it moist.

Question 19: Pitch of the voice is lower in males than females as the vocal cords of man are
(a) Thicker and longer
(b) Thinner and longer
(c) Thicker and shorter
(d) Thinner and shorter
Show Answer & Explanation

Answer: (a) Thicker and longer

Explanation:
1. In males, vocal cord is thicker and longer than females and pitch is affected by this Male → Low pitch and female → High pitch.

Question 20: Which of the following statement is not true for man?
(a) Forceful expiration is an active process
(b) Mammals have negative pressure breathing
(c) Internal intercostal and abdominal muscles are muscles of forceful inspiration
(d) Respiration excretes CO2, water etc.
Show Answer & Explanation

Answer: (c) Internal intercostal and abdominal muscles are muscles of forceful inspiration

Explanation:
1. Internal intercostal muscle Muscles of Abdominal muscle forceful expiration.

Question 21: The ventilation movements of the lungs in mammals are governed by
(a) Muscular walls of lung
(b) Diaphragm
(c) Costal muscles
(d) Both (2) & (3)
Show Answer & Explanation

Answer: (d) Both (2) & (3)

Explanation:
1. Inspiration and expiration both governed by diaphragm and costal muscles.

Question 22: In lungs, the air is separated from the venous blood through
(a) Transitional epithelium of alveoli + squamous epithelium of blood vessel
(b) Squamous epithelium of alveoli + endothelium of blood vessel
(c) Squamous epithelium of alveoli + cubical epithelium of blood vessel
(d) Cubical epithelium of alveoli + columnar epithelium of blood vessel
Show Answer & Explanation

Answer: (b) Squamous epithelium of alveoli + endothelium of blood vessel

Explanation:
1. Alveolar-capillary membrane or respiratory membrane or diffusion membrane, made up of (1) Thin squamous epithelium of alveoli (2) Basement membrane (3) Endothelial lining of alveolar capillary/blood vessel.

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Breathing and Exchange of Gases Objective Questions & Solutions for NEET Biology

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