Question

Choose the correct answer from the alternatives given.
After oxygen diffusion into pulmonary capillaries, it diffuses into, and binds with

• A. interstitial fluid; red blood cells
• B. interstitial fluid; carbon dioxide
• C. red blood cells; haemoglobin
• D. red blood cells; carbon dioxide

Answer 1

The correct option is C red blood cells; haemoglobin

Oxygen diffuses through the capillaries in the lung alveoli (the pulmonary capillaries) and binds to the protein haemoglobin present in the red blood cells. Hemoglobin is made up of four subunits and each haemoglobin molecule can bind up to four oxygen molecules. So, the correct option is 'red blood cells; haemoglobin'.