Free Gaseous Exchange in Lungs MCQs with Answers
47 Gaseous Exchange in Lungs MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Gaseous exchange in the lungs occurs across the thin, moist alveolar and capillary surfaces, where oxygen and carbon dioxide diffuse down partial pressure gradients. The topic covers alveolar adaptations, ventilation, the role of haemoglobin in oxygen transport, carbon dioxide carriage, and the difference between external gas exchange and cellular respiration.
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47 questions · page 2 of 3
- A. I
- B. III
- C. I and III
- D. II and III
Explanation: The correct answer is Option B: IIIThe secretion of surfactant by the epithelial cells of alveoli is the main adaptation that prevents the…
Correct answer: III- A. A
- B. B
- C. C
- D. D
Explanation: The only artery with greater CO₂ concentration is the pulmonary artery, as it carries deoxygenated blood, so B is correct.
Correct answer: B- A. Low in tissues, high in lungs
- B. High in tissues, low in lungs
- C. Equal in tissues and lungs
- D. Varies independently of tissues and lungs
Explanation: The correct answer is that the relative oxygen concentration is low in body tissues and high in the lungs.
Correct answer: Low in tissues, high in lungs- A. High concentration of oxygen in blood
- B. Lower pressure of nitrogen in atmosphere
- C. Higher pressure of carbon dioxide in blood
- D. Low temperature of body in cold environment
Explanation: The correct answer is Option C:higher pressure of carbon dioxide in blood.This is because an increase in carbon dioxide levels in the…
Correct answer: Higher pressure of carbon dioxide in blood- A. Frog
- B. Hydra
- C. Cockroach
- D. Earthworm
Explanation: The correct answer is frog. Frogs have adapted to their environment by developing a moist skin that allows for cutaneous respiration…
Correct answer: Frog- A. Lungs
- B. Trachea
- C. Body tissue
- D. Diaphragm
Explanation: The correct answer is the lungs. In the context of respiratory physiology, the lungs play a crucial role in gas exchange.
Correct answer: Lungs- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: In fish, countercurrent exchange is a highly efficient system for gas exchange in the gills, where water and blood flow in opposite…
Correct answer: Option D- A. Has more affinity with oxygen
- B. Loses oxygen at PO2 60mmHg
- C. Transports oxygen
- D. Has four iron atoms in molecule
Explanation: Hemoglobin indeed releases oxygen to tissues when the partial pressure of oxygen (PO2) decreases, which typically happens around 40 mmHg…
Correct answer: Loses oxygen at PO2 60mmHg- A. O2
- B. CO2
- C. CO
- D. H2
Explanation: If the pH of blood is lower than normal (normal physiological pH is 7.4), then the haemoglobin does not bind oxygen as well.
Correct answer: O2- A. 19.6 ml/100 ml of blood
- B. 50 ml/100 ml of blood
- C. 54 ml/100 ml of blood
- D. 96 ml/100 ml of blood
Explanation: The venous blood in tissues has 54 ml carbondioxide/100 ml of blood.
Correct answer: 54 ml/100 ml of blood- A. 21%
- B. 16%
- C. 79%
- D. 4%
Explanation: The amount of oxygen in exhaled air is 16% whereas in inhaled air it is 21% as the body absorbs oxygen for aerobic respiration to occur.
Correct answer: 16%- A. As bicarbonate ions
- B. In the form of dissolved gas molecules
- C. By binding to R.B.C
- D. As carbamino haemoglobin.
Explanation: The correct option is a) as bicarbonate ions.Explanation of each option:A.
Correct answer: As bicarbonate ions- A. Myoglobin
- B. Globin
- C. Haemoglobin
- D. Hemocyanin
Explanation: Myoglobin is a pigment that has the highest affinity to bind with oxygen.
Correct answer: Myoglobin- A. O2
- B. CO2
- C. CO
- D. H2
Explanation: The Bohr effect describes hemoglobin's lower affinity for oxygen secondary to increases in the partial pressure of carbon dioxide and/or…
Correct answer: O2- A. Blood buffer
- B. Neutralization of H2CO3 by Na2CO3
- C. Absorption by leukocytes
- D. Non-accumulation
Explanation: During the transport of carbon dioxide, the blood does not become acidic due to the presence of buffering systems in the blood.When carbon…
Correct answer: Blood buffer- A. Blood buffer
- B. Neutralization of H2CO3 by Na2CO3
- C. Absorption by leukocytes
- D. Non-accumulation
Explanation: Option A: Although much COz is carried-in blood, blood does not become acidic.
Correct answer: Blood buffer- A. 15 ml/100 ml of blood
- B. 19.6 ml/100 ml of blood
- C. 20.1 ml/100 ml of blood
- D. 200 ml/100 ml of blood
Explanation: In 100 ml of blood, there is about 15 g of Hb, so 100 ml of blood has the capacity to bind 19.6ml of oxygen.
Correct answer: 19.6 ml/100 ml of blood- A. Increases many folds
- B. Decreases
- C. Remains constant
- D. Is doubled
Explanation: Since CO2 reacts with water to form carbonic acid, an increase in CO2 results in a decrease in blood pH resulting in haemoglobin proteins…
Correct answer: Decreases- A. Air sac
- B. Trachea
- C. Larynx
- D. Bronchioles
Explanation: Option [a] Air sacs, and alveoli are present at the end of bronchioles in lungs where lungs and blood exchange oxygen and carbon dioxide…
Correct answer: Air sac- A. It must be permeable
- B. It must be thick for low diffusion
- C. It should be non-vascularized
- D. It should have low ventilation mechanism
Explanation: Respiratory surfaces, such as the alveoli in the lungs, must be permeable to allow the exchange of gases (oxygen and carbon dioxide)…
Correct answer: It must be permeable