Final answer:
Turner syndrome is the condition in which an individual, typically female, has only one X chromosome (XO), leading to underdeveloped sexual characteristics and sterility.
Step-by-step explanation:
Humans with only one sex chromosome (XO), which leads to underdeveloped sexual characteristics and sterility, are experiencing a condition known as Turner syndrome. This genetic disorder is characterized by females having a single X chromosome instead of the typical two (XX) sex chromosomes. Short stature, webbed skin in the neck region, hearing and cardiac impairments are also characteristic of Turner syndrome.
In the presence of abnormal numbers of X chromosomes, cells inactivate all but one X chromosome to balance gene expression. However, individuals with Turner syndrome only have one X chromosome, so there is no possibility for inactivation and the full range of developmental impairments associated with this condition manifests, including sterility.