The common point of attachment of all the arms of polytene chromosome, is known as

$A$ : Polyploids with odd number of chromosomes are propagated vegetatively.
$R$ : Seed formation is absent due to meiotic abnormality.

Animal which remains male initially, then changes to female $(Tapeworm\, proglottides)$ is called

Hugo de Vries formulated the “Mutation Theory'' based on the experiments he conducted on

Who discovered $R{h^ – }$ factor