For ethical reasons I would assume the application requires the applicant to disclose the gender. For example, when applying to accommodation at your university, students who wish to be in a single-gender dorm (Males or females alone) should be allowed to. Without the disclosure of your gender, there's a chance that people will end up in dorms which they don't wish to be in. And besides, I would imagine universities are not biased on genders. The difference in the female:male ratio (Firm choice is 4 female students to every 1 male) could be solely based on the gender of the applicants. For example, maybe a larger majority of students that apply to that university may be female.
In terms of companies, if you know that a company is underpaying a member of staff based on their gender, especially for a job of the same tier/variety as a member of staff of the other sex, you have the right to take the company to court. There has been a law put in place that it is illegal to alter rate of pay for staff based on their gender.