The correct option is 2 and 3 only.
Explanation
Respiration involves the exchange of gases (oxygen and carbon dioxide) between the atmosphere and the body's tissues. Blood serves as the medium for the transport of these gases. The solubility of gases and the chemical properties of blood components (like haemoglobin and plasma) determine the mode of transport.
Statement-wise Analysis
- Statement 1 is Incorrect. Haemoglobin, the red pigment in Red Blood Corpuscles (RBCs), has a high affinity for oxygen. It binds reversibly with oxygen to form oxyhaemoglobin. Each haemoglobin molecule can carry a maximum of four molecules of oxygen. This affinity is crucial for transporting oxygen from the lungs to the tissues.
- Statement 2 is Correct. While strictly speaking, only about 7% of Carbon Dioxide (CO2) is transported in a physically "dissolved state" in plasma, the majority (approximately 70%) is transported as bicarbonate ions (HCO3-). These bicarbonate ions are formed within RBCs but diffuse out to be carried dissolved in the blood plasma. Therefore, in the broader context of transport medium (plasma vs. RBC structure), the bulk of CO2 travels within the plasma component.
- Statement 3 is Correct. The solubility of Carbon Dioxide in water is approximately 20-25 times higher than that of Oxygen. This high solubility allows a significant amount of CO2 to diffuse across the diffusion membrane per unit of partial pressure difference compared to O2.
Key Takeaway
Oxygen is primarily transported bound to
haemoglobin (97%), whereas
Carbon Dioxide is primarily transported as
bicarbonate ions in the plasma (70%), owing to its higher solubility and reaction with water.