WAEC - Biology (2002 - No. 52)
In humans, sex is determined by
two homologous chromosomes
a dominant gene for maleness present in a male
two similar sex chromosomes in the male and dissimilar in the female
the differences in the nature of the X and Y chromosomes in the male.
Explication
In humans, sex is determined by the difference in the nature of the X and Y chromosomes in males. Females have two of the same kind of sex chromosome (XX), while males have two distinct sex chromosomes (XY). The presence of the Y chromosome determines maleness because it carries the SRY gene, which triggers the development of male characteristics. The X chromosome carries genes related to both male and female sexual development.