Answer:
Attached to the heme part of hemoglobin.
Step-by-step explanation:
These 3 statements are correct about CO2 transport:
1) Hemoglobin or Hb is known as a protein that is found in RBCs that carries CO2 to the lungs and O2 to cells. CO2 is carried by Hb as carbamino-hemoglobin. Binding of CO2 to Hb occurs because in the tissues the pO2 is low and pCO2 is high. CO2 and O2 combine with Hb to form Carbaminohaemoglobin. So, 20% of CO2 is carried in the form of carbamino-hemoglobin.
2) The enzyme known as carbonic anhydrase catalyzes a reaction in the RBC, where CO2 and H2O are converted into bicarbonate and hydrogen ion and in the tissues, bicarbonate diffuses out of the RBC into the plasma, where it works as a very important pH buffer.
4) 1st, CO2 is more soluble in blood than O2. About 5-7% of all CO2 is dissolved in the plasma. 2nd, CO2 can bind to plasma proteins or can enter RBC and bind to Hb. This form transports about 10% of the CO2.