Examine the physiological conditions favoring gas diffusion in human body:
I. Factors favor diffusion of O2 from alveoli to tissues. II. Factors favor diffusion of CO2 from tissues to alveoli. III. Partial pressure gradients for O2 and CO2 are in opposite directions. IV. CO2 diffuses from alveoli into tissues.
Explanation: Statements I, II, and III are correct. Oxygen diffuses from alveoli to tissues, whereas carbon dioxide diffuses from tissues to alveoli due to opposite partial pressure gradients. Statement IV is incorrect because CO2 diffuses from tissues to alveoli, not the reverse.
Question 72 of 100
📘 CLASS XI
Compare pO2 and pCO2 values between alveolar air and oxygenated blood:
I. Alveolar pO2 (104 mm Hg) > Oxygenated blood pO2 (95 mm Hg). II. Alveolar pCO2 (40 mm Hg) = Oxygenated blood pCO2 (40 mm Hg). III. Deoxygenated blood pO2 (40 mm Hg) < Alveolar pO2 (104 mm Hg). IV. Deoxygenated blood pCO2 (45 mm Hg) > Alveolar pCO2 (40 mm Hg).
Explanation: All four statements correctly compare the partial pressures of oxygen and carbon dioxide between alveolar air, oxygenated blood, and deoxygenated blood.
Question 73 of 100
📘 CLASS XI
Which statement combination regarding partial pressure of oxygen in tissues is correct?
I. pO2 in tissues is 40 mm Hg. II. pO2 in tissues is equal to pO2 in deoxygenated blood. III. pO2 in tissues is lower than pO2 in oxygenated blood (95 mm Hg). IV. pO2 in tissues is 104 mm Hg.
Explanation: Statements I, II, and III are correct because tissue pO2 is about 40 mm Hg, equal to deoxygenated blood and lower than oxygenated blood. Statement IV is incorrect because 104 mm Hg is the pO2 of alveolar air.
Question 74 of 100
📘 CLASS XI
Which statement combination regarding partial pressure of CO2 in tissues is correct?
I. pCO2 in tissues is 45 mm Hg. II. pCO2 in tissues is equal to pCO2 in deoxygenated blood (45 mm Hg). III. pCO2 in tissues is higher than pCO2 in oxygenated blood (40 mm Hg). IV. pCO2 in tissues is 0.3 mm Hg.
Explanation: Statements I, II, and III are correct because tissue pCO2 is about 45 mm Hg, equal to deoxygenated blood and higher than oxygenated blood. Statement IV is incorrect because 0.3 mm Hg is the pCO2 of atmospheric air.
Question 75 of 100
📘 CLASS XI
Analyze the structural organization of alveolar epithelium and capillary endothelium:
I. Alveolar wall is composed of thin squamous epithelium. II. Capillary wall is composed of a single layer of endothelial cells. III. Basement substance lies between alveolar epithelium and capillary endothelium. IV. Alveolar wall is composed of stratified keratinized epithelium.
Explanation: Statements I, II, and III are correct because the alveolar wall is lined by simple squamous epithelium, capillaries are lined by a single endothelial layer, and a basement substance lies between them. Statement IV is incorrect because alveoli are not lined by stratified keratinized epithelium.
Question 76 of 100
📘 CLASS XI
Consider the transport modes of oxygen in human blood:
I. About 97 per cent of O2 is transported by RBCs in blood. II. The remaining 3 per cent of O2 is carried in a dissolved state through plasma. III. 100 per cent of O2 is carried as bicarbonate ions in plasma. IV. Oxygen is primarily transported as carbamino-haemoglobin.
Explanation: Statements I and II are correct. About 97% of oxygen is transported by RBCs as oxyhaemoglobin and about 3% remains dissolved in plasma. Statements III and IV are incorrect because bicarbonate ions and carbamino-haemoglobin are forms of CO2 transport.
Question 77 of 100
📘 CLASS XI
Regarding haemoglobin structure and oxygen binding, analyze the statements:
I. Haemoglobin is a red coloured iron-containing pigment present in RBCs. II. O2 can bind with haemoglobin in a reversible manner to form oxyhaemoglobin. III. Each haemoglobin molecule can carry a maximum of four molecules of O2. IV. Each haemoglobin molecule binds irreversibly to eight O2 molecules.
Explanation: Statements I, II, and III are correct. Haemoglobin is an iron-containing red pigment that reversibly binds a maximum of four oxygen molecules. Statement IV is incorrect because binding is reversible and limited to four O2 molecules.
Question 78 of 100
📘 CLASS XI
Which factors influence the binding of oxygen with haemoglobin?
I. Partial pressure of O2 (pO2). II. Partial pressure of CO2 (pCO2). III. Hydrogen ion concentration (H+). IV. Temperature.
Explanation: All four factors influence oxygen binding with haemoglobin. The affinity of haemoglobin changes with pO2, pCO2, H+ concentration, and temperature.
Question 79 of 100
📘 CLASS XI
Consider the Oxygen Dissociation Curve:
I. A sigmoid curve is obtained when percentage saturation of Hb with O2 is plotted against pO2. II. It is highly useful in studying the effect of factors like pCO2 and H+ concentration on O2 binding. III. A linear straight-line graph is obtained when percentage saturation of Hb is plotted against pCO2. IV. Sigmoid shape indicates non-cooperative binding of oxygen.
Explanation: Statements I and II are correct. Oxygen dissociation curve is sigmoid when Hb saturation is plotted against pO2 and is useful in studying factors affecting oxygen binding. Statements III and IV are incorrect.
Question 80 of 100
📘 CLASS XI
Which environmental factors in alveoli favor oxyhaemoglobin formation?
I. High pO2 II. Low pCO2 III. Lesser H+ concentration IV. Lower temperature
Explanation: All four factors present in the alveoli, namely high pO2, low pCO2, low H+ concentration, and lower temperature, favor oxyhaemoglobin formation.
