Question

$Rh$ factor is present in

• A. all vertebrates
• B. all mammals
• C. all reptiles
• D. man and rhesus monkey only

Answer 1

Answer: (D)

A protein named rhesus antigen is present on the surface of red blood corpuscles in many humans. It was discovered in $1940$ by Landsteiner and Wiener in the blood of Rhesus monkey, hence its name. Depending on the race, $85$ to $99$ percent of the white population have this rhesus antigen (also called $Rh$ factor) and are called $Rh$ positive $(R{h}^{+})$. Others who do not have this factor are known as $Rh$ negative $(R{h}^{-})$. $R{h}^{+}$ is dominant to $R{h}^{-}$.