12. Individuals with Type O blood are able to produce both Anti-A and Anti-B antibodies, while individuals with Type AB blood produce neither of these antibodies. Explain why this is the case. How does this relate to the idea that people with Type AB blood are often referred to as universal recipients for transfusions

Blood group O individuals are able to produce Anti- A and Anti- B and are often referred to as UNIVERSAL DONORS, while blood group AB individuals produces none and are often referred to as UNIVERSAL RECIPIENTS

Explanation:

Two antigens, type A and type B, occur on the surfaces of the red blood cells in a large proportion of human beings. These antigens are referred to as agglutinogens because they often cause blood cell agglutination during blood transfusion. Because of the way these antigens are inherited, people may have neither of them on their cells , they may have one or they may have both simultaneously.

When type A antigen and type B antigen is not present in an individuals reb blood cell as seen in blood group O, antibodies known as Anti-A and Anti- B develops in the plasma. This is because small amounts of type A and type B antigens enter the body through food, bacteria and other ways and they initiate the development of anti A and Anti- B antibodies in their plasma.

Furthermore, individuals with blood type AB has antigen A and B on their red blood cells and therefore do not develop antibodies A and B in their plasma. This makes them universal recipient as their blood do not discriminate any ABO blood group during blood transfusion.

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.