Principles of Inheritance and Variation — BIOLOGY STD 12 Science — Question

1.

Mendelian disorders are due to alteration or mutation in a single gene.

Chromosomal disorders are those caused due to absence or excess presence of one or more chromosome(s) or abnormal arrangement of one/more chromosome(s).

2.

They are transmitted to the progeny in the same way as Mendelian principles of inheritance.

They are not transmitted as the affected individual is sterile.

3.

The pattern of inheritance can be traced in a family tree by pedigree analysis, e.g. Phenylketonuria, Colourblindness.

The disease can be confirmed by karyotyping, e.g. Down's syndrome, Turner's syndrome.