NEET2013ZoologyPrinciples of Inheritance and VariationActual
In our society women are blamed for producing female children. Choose the correct answer for the sex-determination in humans.
Options
- ADue to some defect like aspermia in man
- BDue to the genetic make up of the egg
- CDue to the genetic make up of the particular sperm which fertilizes the egg
- DDue to some defect in the women
Correct answer
B. Due to the genetic make up of the egg
Step-by-step solution
In human beings both females and males have the same number of chromosomes (23 pairs). Females are homogametic with XX chromosomes (22 pairs + XX ). They produce ova having X chromosome. All ova are similar. Males are heterogametic with X and Y-chromosomes (22 pairs + XY ) . They produce two kinds of sperms, one type with X-chromosome and other with Y-chromosome. On fertilization, the zygotes may have either the X X or X Y . The zygote with XX becomes the female and the zygote with X Y becomes the male. The sex of