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Cross-Dressing or Crossing-Over?

Sex Testing of Women Athletes


Maureen Knabb
Department of Biology
West Chester University of Pennsylvania
Joan Sharp
Department of Biological Sciences
Simon Fraser University


In this “clicker case,” students learn about sex determination, meiosis, and chromosomal “crossing over” through the story of Santhi Soundararajan, an athlete from Kathakkurichi, India, who was stripped of a medal at the 2006 Asian Games after failing to pass a sex test. The case is called a clicker case because it combines the use of student personal response systems (clickers) with case teaching methods and formats. The case itself is a PowerPoint presentation (~2 MB) shown in class that is punctuated by questions students respond to using their clickers. It can be adapted for use without these technologies. Developed for an introductory biology class for both majors and non-majors, the case could also be used in an anatomy and physiology course or an endocrinology course.


  • Explain the basis of sex determination in mammals.
  • Describe the sources of variation in daughter cells produced by meiosis.
  • Understand the role of the SRY gene in the determination of a human embryo as male.
  • Explain how human sex reversal (XX/SRY+ male; XY/SRY- female) may take place.


Crossing-over; gametogenesis; gender testing; sex testing; meiosis; cell division; karyotype; sex determination; sex reversal; SRY gene; Santhi Soundararajan

Topical Areas

Legal issues, Social issues

Educational Level

Undergraduate lower division



Type / Methods

Clicker, Interrupted, Dilemma/Decision



Subject Headings

Biology (General)  |   Cell Biology  |   Physiology  |   Sports Science  |  

Date Posted


Teaching Notes

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Supplemental Materials

The following Supplemental(s) are recommended for use in association with this case study.

  Interactive Module: Sex Verification Testing of Athletes hhmi/
   Lecture: Deciphering the Language of Sex hhmi/

Answer Key

Answer keys for the cases in our collection are password-protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, begin the process by registering.


The following video(s) are recommended for use in association with this case study.

  • Meiosis (Animation) hhmi/
    Meiosis, the form of cell division unique to egg and sperm production, sets the stage for sex determination by creating sperm that carry either an X or a Y sex chromosome. But what is it about the X or Y that determines sex? The animation presented in this video connects meiosis and sex determination. Running time: 5:53 min. Produced by: HHMI BioInteractive.
  • The Y Chromosome (Animation) hhmi/
    The Y chromosome has been likened to a hall of mirrors because its sequence contains many sections that appear to be palindromes. These palindromes provide a clue to some interesting events that may have occurred during the course of the chromosome's evolution. Running time: 2:46 min. Produced by: HHMI BioInteractive.


Eric Ribbens
Biological Sciences
Western Illinois University
Macomb, IL
This a great case, and can be made even stronger with two modifications:
  1. The "emotional" impact can be substantially strengthened by at intervals asking students this clicker question: "What do you think Santhi is?" (A: Boy, B: Girl, C: Don't Know) and then at the very end I tell them they have to decide one gender or the other, there is no "don't know" option.
  2. The recent updates of her story should be added. Santhi was fired from her coaching job and found work in a brick-making factory, very hard work for low pay. Reasons for firing are unclear but probably related to her gender controversy. And even more recently, this news story: "BANGALORE: Santhi Soundarajan, who was stripped of her 800m silver medal after failing a gender test at the 2006 Doha Asian Games and was later forced to work as a labourer in a brick kiln, has finally been given the opportunity to realise her dream of becoming a qualified athletics coach. The government has removed its rider of ascertaining her gender before allowing her to pursue the diploma course in Patiala."