Sponsor Area

Principles Of Inheritance And Variation

Question
CBSEENBI12047599

Down's syndrome is caused by an extra copy of chromosome number 21. What percentage of a normal father would be affected by this disorder?

  • 50%

  • 25%

  • 100%

  • 75%

Solution

A.

50%

Down's syndrome is the result of trisomy in which chromosome number 21st contains an extra copy of chromosome (2A + 1). Affected mother will produce 50% normal egg cells and rest 50% eggs are of abnormal type.