Zoology - Principles of Inheritance and Variation Question with Solution | TestHub

Chromosomal disorder occurs when there is addition or deletion of chromosome in the individual. In case of trisomy of the 21st chromosome causes Down's syndrome. This results in mental retardation and physical development is retarded as well. The palm of the individual is broad with characteristic palm crease.

Klinefelter's syndrome is a condition where individual has the chromosomal combination as$44+\mathrm{X}\mathrm{X}\mathrm{Y}$with an extra X chromosome. Such individual is sterile. Also, individual has an overall masculine development with certain feminine characteristics.

Turner's syndrome occurs when the chromosomal count is$44+\mathrm{ }\mathrm{X}0$, where the last pair has a missing chromosome. The individual is sterile female with webbed neck.

Phenylketonuria is an inborn error of metabolism where the individual has reduced metabolism of the amino acid phenylalanine. Such mutation leads to mental retardation, with reduction in hair and skin pigmentation.

Black urine due to exposure to air occurs in a genetic condition called Alkaptonuria.