Answer: Antigens
Explanation: The ABO system of blood grouping is based on the basis of the type of antigens that are present in the red blood cells. Erythrocytes is another name for the red blood cells. Antigens are molecules that are capable of eliciting immune response. There are two types of antigens: antigen A and B. Blood type A has only antigen A, blood type B has only antigen B, blood type AB has both antigen A and B while blood type O has no antigen (neither A nor B antigen).
Similarly, Rh trait is determined by the presence or absence of rhesus antigen in the erythrocytes. Rhesus antigen is an antigen first discovered in rhesus monkey. Rh+ indicates the presence of rhesus antigen in the red blood cells while Rh- indicates the absence of rhesus antigen in the red blood cells.
The anatomical term meaning away from the midline is lateral
The Punctuated Equilibrium theory proposes that a specie that appears in the fossil record will become stable. To support this theory, a fossil record serves as an evidence which includes transitional fossils. Transitional fossils refers to the remains of an organism that still exhibit traits to both the ancestral and descendant group.
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