Chiasmata firstly seen in

Knowing that albinism is determined by a recessive gene in man; presence of albinism in children born to a couple proves that

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

The recessive genes located on $X$-chromosome in humans are always

All the sons are haemophilic and daughter are normal of a haemophilic father and normal mother. This character is