Which of the following reactions takes place in red blood cells in the capillaries surrounding the cells of active tissues?

a. h2co3 < --> h2o + co2

b. h2co3 < --> h+ + hco3-

c. hhb + o2 < --> hhbo2- + h+

d. hhbco2 < --> hhb + co2

B

Explanation:

This reaction demonstrated Bohr effect. it takes place in the  cytoplasm  of RBC , because this is the location of the enzyme carbonic anhydrase which catalyzed it .  

The hydrogen ion and bicarbonate  are transferred out  of the  RBC into plasma. Chloride ion diffused into the RBC to neutralize drop in pH(chloride shift).

 The hydrogen ion is mobbed by haemoglobin in its buffer effect, while the carbonate is transferred to the lungs  where it is broken down, to release C02 .85% of blood C02 is transported in this form .

The CO2 released out of  the lungs , created a concentration gradient for  influx of Oxygen into the lungs. This is the significance of this reaction.

In addition, Option D which involved direct reaction of C02 with Haemoglobin to form carbaminoheamoglobin  is another reaction which takes place in the RBC. it is a reversible reaction where the C02 is transported to the lungs.10% C02 is tranported in this form,

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.

1. is geographic distribution

2 is increasing complexity

3 is transitional forms