If haploid chromosome number in a cell is $12$. The monosomic number will be

The theory where ratio between the number of $X$-chromosomes and number of complete sets of autosomes will determine the sex is known as

A diseased man marries a normal woman. They get three daughters and five sons. All the daughters were diseased and sons were normal. The gene of this disease is

Edward syndrome is on account of …….

Change of male and female parents during crosses is known as