'Sex' and 'gender' both classify an organism, but in different ways. 'Sex' is what defines organisms as female or male on the basis of their reproductive organs and functions. 'Gender' defines the sexual identity, especially in relation to society or culture, of an organism. Whereas 'sex' just looks primarily at the biological and psychological aspects of an organism to define them, 'gender' looks at the society and culture. You can state that 'sex' is all about the individual, just by himself or herself. 'Gender' has to do with the society and culture that is around them and affects them.
             Now Science plays a roll in the aspect of the difference between 'sex' and 'gender'. Science takes the 'sex', the biological aspect of us and changes it around in order to make it a part of the society and culture that exists around them, thereby changing it to affect what 'gender' is.
             What does it mean to take the biological and use to towards the usage of the society/culture? Two examples of this can be brought from history to help explain this. First one is of J. Marion Sims. He designed the speculum in order to be able to see into the woman, into her vagina. This allowed the men of Science at the time to be able to map out the inner sanctum of the female. This caused the biology of the women to be used to manipulate how gender was seen in terms of man and women in regards to society and social structure. Men were there to just be able to examine the women, to see and look at them. It helped strengthened the barrier between man and woman, between the gender rolls which society had viewed and placed upon both of them.
             This takes us to Sarah Bartman who is our second example of how science and it's relationship to gender. She was a black South African woman who was taken to Europe to be displayed. Science too...