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Q. No.Identify the incorrect statement regarding transport of respiratory gases in humans:
| 1. | Blood is the medium of transport for O2 and CO2. |
| 2. | About 97 per cent of O2 is transported by RBCs in the blood. |
| 3. | Nearly 70 per cent of CO2 is transported by RBCs. |
| 4. | About 7 per cent of CO2 is carried in a dissolved state through plasma |
Subtopic: Human Heart: Cardiac Cycle | Atherosclerosis, Hypertension & Ventricular Fibrillation | Circulatory Pathways |
87%
From NCERT
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The sino-atrial node is the normal pacemaker of the human heart primarily because:
| 1. | it is made up of special cardiac muscle. |
| 2. | it is richly innervated by autonomic nerve fibres. |
| 3. | it is located in the posterior wall of the right atrium. |
| 4. | it depolarizes at the fastest rate out of the whole nodal tissue. |
Subtopic: Human Heart: Double Circulation | Circulatory Pathways |
71%
From NCERT
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Closed circulatory systems, seen in vertebrates and some invertebrates like annelids, are generally considered more efficient than open circulatory systems. Which option BEST explains this advantage?
| 1. | Closed systems allow blood to carry more hemoglobin molecules per cell, leading to greater oxygen-binding capacity than open systems. |
| 2. | Closed systems ensure that blood never comes into contact with interstitial fluid, preventing any loss of plasma or nutrients into tissues. |
| 3. | Closed systems can function without a heart, relying entirely on peristaltic vessel movement, making circulation continuous and energy-efficient. |
| 4. | Blood is completely enclosed within vessels, maintaining higher pressure, allowing faster, more directed flow, efficient nutrient and oxygen delivery, and better regulation of blood supply to specific organs as per metabolic demand. |
Subtopic: Circulatory Pathways |
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