Biology

Respiration and Gas Transport

606 Questions

Respiration and gas transport deal with the physiological mechanisms of breathing, including the role of hemoglobin in oxygen transport and the removal of carbon dioxide from the blood. Questions cover both aerobic and anaerobic processes, along with related phenomena like altitude sickness. This human biology topic is a staple in the science sections of competitive tests.

Oxygen and hemoglobin transportAnaerobic respiration effectsCarbon dioxide removalAltitude sickness causesBreathing rate regulation

Respiration and Gas Transport Questions

Multiple choice

Carbonic anhydrase is the vital respiratory enzyme present in red blood cells catalysing the interconversion of carbon dioxide (CO2) and carbonic acid (H2CO3), thus influencing CO2 transport in the blood. Which of the following elements is found to play an important mediator of the enzyme carbonic anhydrase?

  1. Copper

  2. Molybdenum

  3. Iron

  4. Zinc

  5. Manganese
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Zinc plays a vital role as coenzyme or activator of various metabolic enzymes as in case of zinc-mediated role of the enzyme carbonic anhydrase.

Multiple choice

The partial pressure of carbon dioxide will be the highest in

  1. inhaled gas

  2. exhaled gas

  3. systemic venous blood

  4. systemic arterial blood
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Systemic venous blood is the blood which has given up its oxygen to the tissues and is carrying carbon dioxide back through the systemic veins for gaseous exchange in the lungs. So, the partial pressure of carbon dioxide will be the highest in systemic venous blood.

Multiple choice

The elemental regulating variable of the central chemoreceptors is

  1. PaCO2

  2. PaO2

  3. SaO2

  4. CaO2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Special chemical receptors close to the aorta and carotid arteries are highly responsive to an increase in carbon dioxide or acid concentration, or to a decrease in the pressure of oxygen (PaO2). When these receptors sense acidity or low oxygen, they stimulate the brain respiratory centre to increase the speed and depth of breathing.

Multiple choice

Mr. Sharma is a hypoxic patient. His blood gas measurements indicate that his systemic arterial oxygen content is normal but his systemic venous oxygen content is low. This is the characteristic of

  1. diffusion limitation

  2. perfusion limitation

  3. anemic hypoxia

  4. stagnant hypoxia
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Stagnant hypoxia occurs when something obstructs the flow of the blood carrying an adequate amount of oxygen. The major causes include heart attack, pulmonary embolism, chronic alveolar hypoventilation and choking.

Multiple choice

Raghav suddenly fainted in the school. Doctors told his teachers that he was suffering from decrease in PCO2, decrease in H+ and increased PO2 . This condition is known as

  1. hyperventilation

  2. hypoventilation

  3. hypercapnia

  4. hypoxia
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

It is the state in which a reduced amount of air enters the lungs alveoli resulting in decreased levels of oxygen and increased levels of carbon dioxide of the blood. Thus, the case dissused above is a case of hypoventilation.

Multiple choice

Amit noticed his bluish colour of the skin and mucous membranes and went to the doctor. The doctor told him that it was a cyanosis, which indicates the blood to have

  1. high carbon dioxide concentration

  2. high carbon monoxide concentration

  3. high 2, 3-diphosphoglycerate concentration

  4. low hemoglobin concentration
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When the hemoglobin level is slightly below normal in an individual,  then the feeling of tiredness, headache, dizziness, fatigue and lack of concentration are common. Physically, the visible signs are pale skin with bluish colour of the skin and mucous membranes, nail beds and gums.

Multiple choice

Assertion (A) : Citric acid has less 'Respiratory Quotient' in comparison to lipids. Reason (R) : Citric acid has relatively more oxygen in comparison to lipids

  1. Both A and R are individually true and R is the correct explanation of A.

  2. Both A and R are individually true but R is not the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The Respiratory Quotient (RQ = CO2 produced/O2 consumed) depends on substrate composition. Citric acid (C6H8O7) has RQ = 6/7 ≈ 0.86, while lipids typically have RQ around 0.7. Citric acid actually has HIGHER RQ than lipids because it contains more oxygen relative to carbon. Therefore Assertion A is false (citric acid has MORE RQ, not less). Reason R is true (citric acid does have relatively more oxygen than lipids).

Multiple choice

Which of the following statements is/are false?

a. The respiratory quotient depends upon the type of respiratory substrate used during respiration. b. In oxidative phosphorylation, O2 is the ultimate acceptor of electrons and it gets reduced to water. c. The ratio of volume of CO2 consumed to the volume of O2 evolved in respiration is called as respiratory quotient.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This is the correct option as this statement is false.

Multiple choice

Which of the following is not a reason due to which multicellular organisms need more oxygen than unicellular organisms?

  1. The rate of respiration is much higher in multicellular organisms than in unicellular organisms.

  2. Multicellular organisms are made of billions of cells.

  3. Cells are not directly in contact with the environment or air.

  4. In blood, oxygen is slowly taken up by haemoglobin.

  5. The absorbed oxygen is rapidly transported to all the cells.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In multicellular organisms the blood oxygen is very quickly taken up by haemoglobin in the red blood cells making the process of diffusion faster.

Multiple choice

For respiration in deep sea, divers use a mixture of

  1. oxygen and nitrogen

  2. oxygen and hydrogen

  3. oxygen and carbon dioxide

  4. oxygen and helium
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Oxygen is toxic at sufficient partial pressure. Helium is not toxic, thus, it is mixed with oxygen for sea diving.

Multiple choice

How does oxygen reach all parts of the body?

  1. It combines with the digested food.

  2. It gets attached to WBC (White Blood Cells).

  3. It gets attached to haemoglobin which is present in RBC (Red Blood Cells)

  4. It flows directly into vessels.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Yes, it is correct.The haemoglobin present in RBC gets attached to oxygen and then transports it into all the parts of body.

Multiple choice

Which of the following statements is/are false?

a. Haemoglobin is present in the RBCs as a red-coloured iron-containing pigment. b. Oxygen plays quite a insignificant role in the regulation of respiratory rhythm. c. Vital capacity is the total volume of air accommodated in the lungs at the end of a forced inspiration.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is the correct option as this statement is false. Total lung capacity is the total volume of air accommodated in the lungs at the end of a forced inspiration.