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 level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.