The answer is sex. In addition, sex denotes to physical or biological alterations among males and females also together with primary sex features which are the reproductive system and subordinate features such as stature and muscularity. A sex of a person as per-determined by his or her biology does not always resemble with his or her gender. Hence, the terms sex and gender are not substitutable. As the term sex denotes to biological or physical differences the features of sex will not differ considerably among dissimilar human civilizations.