Which of the following statements are correct regarding respiratory gases and blood? 1. Haemoglobin in red blood corpuscles has no affinity for oxygen. 2. Carbon dioxide is mostly transported dissolved in plasma. 3. Carbon dioxide is more soluble in water than oxygen. Select the correct answer using the code below:

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.

NCERT Class 10 Science — Chapter 1: Life Processes

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Which of the following statements are correct regarding respiratory gases and blood?

Haemoglobin in red blood corpuscles has no affinity for oxygen.
Carbon dioxide is mostly transported dissolved in plasma.
Carbon dioxide is more soluble in water than oxygen.

Select the correct answer using the code below:

Official previous-year question

Verified 1 Aug 2026.

Options

A1 and 2 only
B2 and 3 only
C2 only
D1, 2 and 3

Did you get this right?

Solution

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.

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More from Chapter 1: Life Processes

Which enzyme, present in saliva and pancreatic juice, is primarily responsible for the breakdown of starch into simpler sugars?

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The accumulation of which compound in muscle cells leads to cramps during sudden physical activity or anaerobic respiration?

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Which hair-like structures lining the upper respiratory tract help in filtering air by trapping dust and particles?

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In the circulatory system of fishes, the heart is characteristically composed of how many chambers?

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With reference to maintenance functions in organisms, consider the following statements: 1. The transfer of energy source from outside to inside is referred to as respiration. 2. These processes require energy sourced from outside the body. 3. All organisms obtain energy directly from sunlight. Which of the statements given above is/are correct?

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The correct option is 2 and 3 only.

Explanation

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.