Its the Eccentricity of the earth. (shape of Earth's Orbit around the sun, whether it is more circular or ovular.)
The Type O blood group is commonly called as universal donor because any blood group can receive the O blood group. The blood group O has no antigen. Due to the absence of antigen it doesn't agglutinate when come in contact with other blood groups in the plasma.
The agglutination reaction happens when opposite antigen and antibody reacts with each other. e.g.- Blood group A contains antigen A and antibody b and the blood group B contains antigen B and antibody a. Agglutination reaction occurs when the antigen A reacts with antibody a. As O blood group has no antigen, agglutination reaction doesn't occur.
The macronucleus is the larger elipse-shaped nucleus and takes care of
functions like respiration and digestion. In contrast to this, the
smaller micronucleus is only involved in cell division or reproduction.
