NEET Biology Breathing and Exchange of Gases MCQs Set 16

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

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Multiple Choice Questions

Question 1: Exchange of bicarbonates and chloride ions between RBC and plasma is called:-
(a) Chloride shift.
(b) Bohr's effect.
(c) Haldane's effect.
(d) Intra cellular respiration.
Show Answer & Explanation

Answer: (a) Chloride shift.

Explanation:
1. The exchange of chloride and bicarbonate ions between red blood cells and plasma is called the chloride shift (Hamburger phenomenon).

Teacher's Note:
1. It keeps ionic balance.
2. Bicarbonate and chloride exchange is chloride shift.

Question 2: If CO 2 concentration increases in blood then breathing rate will :-
(a) Increases
(b) Decrease
(c) Stop
(d) Remain unchanged
Show Answer & Explanation

Answer: (a) Increases

Explanation:
1. Raised CO2 stimulates the respiratory centre, so the breathing rate increases.

Teacher's Note:
1. The centre is sensitive to CO2 more than to O2.
2. More CO2 means faster breathing.

Question 3: Food and air pathway are divided at :
(a) larynx
(b) pharynx
(c) oesophagus
(d) stomach
Show Answer & Explanation

Answer: (b) pharynx

Explanation:
1. Food and air passages cross in the pharynx; the epiglottis guides them.

Teacher's Note:
1. Air goes to the larynx, food to the oesophagus.
2. They separate at the pharynx.

Question 4: In which of the following animals, respiration occurs without respiratory organ ?
(a) Frog
(b) Fish
(c) Cockroach
(d) Earthworm
Show Answer & Explanation

Answer: (d) Earthworm

Explanation:
1. An earthworm breathes through its moist skin and has no special respiratory organ. Frog has lungs, fish gills and cockroach tracheae.

Teacher's Note:
1. Skin respiration is cutaneous.
2. Earthworm has no respiratory organ.

Question 5: At the time of expiration, diaphragm becomes
(a) Oblique
(b) Normal
(c) Flattened
(d) Dome-shaped
Show Answer & Explanation

Answer: (d) Dome-shaped

Explanation:
1. During expiration the diaphragm relaxes and returns to its dome shape, reducing thoracic volume.

Teacher's Note:
1. It flattens in inspiration.
2. Relaxed diaphragm is dome shaped.

Question 6: The maximum bonding of haemoglobin is with :
(a) Carbonmonoxide
(b) Cabondioxide
(c) Oxygen
(d) Ammonia
Show Answer & Explanation

Answer: (a) Carbonmonoxide

Explanation:
1. Haemoglobin has about 200 to 250 times greater affinity for carbon monoxide than for oxygen.

Teacher's Note:
1. This forms carboxyhaemoglobin.
2. Hb binds CO the strongest.

Question 7: Respiratory centre of brain is sensitive to :
(a) more O2 concentration in blood
(b) more CO2 concentration in blood
(c) accumulation of blood in brain
(d) all of these
Show Answer & Explanation

Answer: (b) more CO2 concentration in blood

Explanation:
1. The respiratory rhythm centre and chemosensitive area are highly sensitive to CO2 and hydrogen ions in the blood.

Teacher's Note:
1. They are less sensitive to O2.
2. The centre senses CO2.

Question 8: Which of the following conditions is responsible for increase in ventilation rate of lungs ?
(a) decrease in O2 content of inhaled air
(b) decrease in O2 content of exhaled air
(c) increase in CO2 content of inhaled air
(d) increase in CO2 content of exhaled air RCISE
Show Answer & Explanation

Answer: (c) increase in CO2 content of inhaled air

Explanation:
1. Hyperventilation can occur when CO2 in the inhaled air rises, since CO2 stimulates the respiratory centre.

Teacher's Note:
1. Fall in O2 acts through chemoreceptors only slightly.
2. More inhaled CO2 raises ventilation.

Question 9: In lungs there is definite exchange of ions between RBC and plasma. Removal of CO2 from blood involves : (a) efflux of Cl— ions from RBC (b) influx of Cl— ions into RBC (c) influx of HCO3- ions into RBC (d) efflux of HCO3- ions from RBC
(a) a, b
(b) a, c
(c) b, c
(d) c, d
Show Answer & Explanation

Answer: (b) a, c

Explanation:
1. In the lungs, bicarbonate ions enter the RBC and chloride ions move out; CO2 is then released from carbonic acid.

Teacher's Note:
1. It is the reverse of the tissue reaction.
2. HCO3 in and Cl out in lungs.

Question 10: After taking a long deep breath we donot respire for some seconds due to :
(a) More CO2 in blood
(b) More O2 in blood
(c) less CO2 in blood
(d) less O2 in blood
Show Answer & Explanation

Answer: (c) less CO2 in blood

Explanation:
1. A deep breath removes CO2 and lowers its level in blood, so the respiratory centre is not stimulated for some seconds.

Teacher's Note:
1. Low CO2 depresses breathing.
2. Less CO2 stops the urge to breathe.

Question 11: Respiration results in :
(a) release of O2
(b) anabolism
(c) transfer of CO2
(d) release of CO2
Show Answer & Explanation

Answer: (d) release of CO2

Explanation:
1. Cellular respiration oxidises food and releases CO2 and energy.

Teacher's Note:
1. O2 is taken in, not released.
2. Respiration releases CO2.

Question 12: Ascent of high mountains may cause altitude sickness in men. Prime cause of this is :
(a) excess of CO2 in blood
(b) decreased efficiency of haemoglobin
(c) decreased partial pressure of O2
(d) decreased proportion of O2 in air
Show Answer & Explanation

Answer: (c) decreased partial pressure of O2

Explanation:
1. At high altitude the partial pressure of oxygen is low, although its percentage in air is the same, so tissues receive less oxygen.

Teacher's Note:
1. This causes mountain sickness.
2. Low pO2 at high altitude.

Question 13: Which of the following statements are true/false ? (a) The blood transports CO2 comparatively easily because of its higher solubility. (b) Approximately 8.9% of CO2 is transported being dissolved in the plasma of blood. (c) The carbondioxide produced by the tissues, diffuses passively into the blood stream and passes into red blood corpuscles and react with water to form H2CO3. (d) The oxyhaemoglobin (HbO2) of the erythrocytes is basic. (e) The chloride ions diffuse from plasma into the erythrocytes to maintain ionic balance.
(a) a,c, and e are true and 'b' and 'd' are false
(b) a, c and e are false and 'b' and 'd' are true
(c) a, b and d are true and 'c' and 'e' are false
(d) a, b and d are false and 'c' and 'e' are true
Show Answer & Explanation

Answer: (a) a,c, and e are true and 'b' and 'd' are false

Explanation:
1. CO2 is about 20 to 25 times more soluble than O2, about 7 percent travels dissolved (not 8.9), HbO2 is acidic and chloride shift occurs. So a, c, e are true and b, d false.

Teacher's Note:
1. Check each statement separately.
2. a, c, e true; b, d false.

Question 14: Statements : (a) Carbonic anhydrase is present in the erythrocytes (b) In erythrocytes the carbondioxide combine with water and is transported
(a) Statement 'a' is correct and is responsible for statement 'b'
(b) Statement 'a' is not correct but statement 'b' is correct
(c) Both 'a' and 'b' are wrong
(d) Statement 'a' is correct but not involved in statement 'b'
Show Answer & Explanation

Answer: (a) Statement 'a' is correct and is responsible for statement 'b'

Explanation:
1. Carbonic anhydrase in erythrocytes speeds the combination of CO2 with water, so a is correct and is responsible for b.

Teacher's Note:
1. The enzyme makes carbonic acid quickly.
2. Statement a explains statement b.

Question 15: Membrane separating air in pulmonary alveoli from blood capillaries :
(a) alveolar epithelium
(b) cardiac epithelium
(c) endothelium of blood capillaries
(d) both '1' and '3'
Show Answer & Explanation

Answer: (d) both '1' and '3'

Explanation:
1. The diffusion membrane has alveolar epithelium and endothelium of capillaries with a basement substance between them.

Teacher's Note:
1. It is very thin.
2. Both layers separate air and blood.

Question 16: For proper transport of O2 and CO2 blood should be
(a) Slightly acidic
(b) Strongly acidic
(c) Strongly alkaline
(d) Slightly alkaline
Show Answer & Explanation

Answer: (d) Slightly alkaline

Explanation:
1. Blood should be slightly alkaline (pH about 7.4) for proper binding and transport of gases.

Teacher's Note:
1. Acidic blood lowers Hb affinity.
2. Blood is slightly alkaline.

Question 17: What would happen when blood is acidic
(a) Binding of oxygen with haemoglobin increases
(b) Red blood corpuscles are formed in higher number
(c) Binding of oxygen with haemoglobin decreases
(d) There is no change in oxygen binding nor number of RBC
Show Answer & Explanation

Answer: (c) Binding of oxygen with haemoglobin decreases

Explanation:
1. Acidic blood (low pH) shifts the dissociation curve to the right, so haemoglobin binds less oxygen. This is the Bohr effect.

Teacher's Note:
1. It helps release of O2 in tissues.
2. Acid lowers O2 binding.

Question 18: Which one of the following statement is correct?
(a) Chest expands because air enters into the lungs
(b) Air enters into the lungs because chest expands
(c) The muscles of the diaphragm contracts because air enters into the lungs
(d) All of the above statements are correct
Show Answer & Explanation

Answer: (b) Air enters into the lungs because chest expands

Explanation:
1. Chest cavity expands first by muscle action, creating lower pressure so that air enters the lungs.

Teacher's Note:
1. Air entry is the result, not the cause.
2. Chest expands and air enters.

Question 19: The combination of oxygen with haemoglobin is called
(a) Oxidation
(b) Oxygenation
(c) Reduction
(d) None of the above
Show Answer & Explanation

Answer: (b) Oxygenation

Explanation:
1. The combination of oxygen with haemoglobin is oxygenation, not oxidation, as iron stays Fe2+.

Teacher's Note:
1. Oxidation would convert Fe2+ to Fe3+.
2. Oxygen binding is oxygenation.

Question 20: The covering of lungs in human is
(a) Peritoneum
(b) Pericardium
(c) Pleural membrane
(d) Glission capsule
Show Answer & Explanation

Answer: (c) Pleural membrane

Explanation:
1. Each lung is covered by a double layered pleural membrane.

Teacher's Note:
1. Pericardium covers the heart.
2. Pleura covers the lungs.

Question 21: Among mammals, the efficiency of ventilation of lungs as compared to reptiles and birds is better developed by the presence of
(a) Ribs & costal muscles
(b) Only ribs
(c) Only costal muscles
(d) Diaphragm
Show Answer & Explanation

Answer: (d) Diaphragm

Explanation:
1. The muscular diaphragm of mammals makes ventilation more efficient than in reptiles and birds, which lack it.

Teacher's Note:
1. Ribs alone are present in reptiles too.
2. The diaphragm improves ventilation.

Question 22: In human respiration takes place in
(a) Cells lining the lungs cavity
(b) Cells found in blood
(c) All living cells of the body
(d) Only RBC
Show Answer & Explanation

Answer: (c) All living cells of the body

Explanation:
1. Respiration, the oxidation of food, takes place in all living cells of the body.

Teacher's Note:
1. Lungs only supply O2.
2. All cells respire.

Question 23: The process of respiration is concerned with
(a) In take of O2
(b) Liberation of O2
(c) Liberation of CO2
(d) Liberation of energy
Show Answer & Explanation

Answer: (d) Liberation of energy

Explanation:
1. Respiration is concerned with the liberation of energy from food in cells, along with O2 use and CO2 release.

Teacher's Note:
1. The energy is stored as ATP.
2. Energy release is its purpose.

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

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