Back to School: Sex Chromosomes Quiz Results

The 23rd Chromosome

This month we’ve run a series of quizzes for the back-to-school season. Here’s are the answers to our third and final quiz. Congratulations to Toni K., who was selected randomly from the large group of test takers who got all the answers right. You can see how you did by comparing with the correct answers below. We hope you had fun. Although we’ve already given out prizes and posted the answers for each quiz, you can always go back and hone your genetic knowledge. 1 Question: What are the “sex chromosomes?” A) The chromosomes that determine whether a person will be male or female. B) A band from the 1980’s. C) The best looking of all the chromosomes, also known as the “sexy chromosome.” D) None of the above. Correct Answer: There may be a band out there called the “Sex Chromosomes,” but we couldn’t find it. The correct answer is A, the sex chromosomes are the chromosomes that determine a person’s sex. 2 Question: It is possible to use DNA to trace a person’s paternal ancestry because the Y chromosome is passed down largely intact from father to son through each generation. Correct Answer: True. Although women do not typically have a Y chromosome, they can trace their paternal ancestry by using the DNA of a brother, father, grandfather, father’s brother or the son’s of her father’s brothes. 3 Question: Men inherit an X chromosome from their mothers and a Y chromosome from their fathers. Correct Answer: True 4 Question: What is mtDNA? A) The Y-chromosomal DNA passed down from father to son. B) A form of motor oil. C) DNA found in mitochondria, the small structures inside of cells with their own DNA, that a mother passes on to her children. D) DNA only passed from mothers to daughters. Correct Answer: The correct answer is C. The mtDNA is the DNA found in mitochondria – the small structures inside of cells with their own DNA – which a mother passes on to her children. 5 Question: When comparing the Y chromosome to the X chromosome, which are true? A) The Y chromosome has 30 times fewer genes than the X chromosome. B) The Y chromosome is way stronger. C) Most of the genes on the Y chromosome define maleness, like male fertility. D) A and C are both correct. E) None of the above are correct. Correct Answer: D, both A and C are correct. The Y chromosome has 30 times fewer genes than the X chromosome; And most of the genes on the Y chromosome define maleness, like male fertility. 6 Question: The Y chromosomes of all living males are related through a single male ancestor who lived over 100,000 years ago. Correct Answer: True 7 Question: Women can trace their paternal lines by: A) Having their father’s brother’s DNA tested. B) Having their father’s DNA tested. C) Having their father’s brother’s son’s DNA tested. D) Having their brother’s DNA tested. E) All of the above. Correct Answer: E, all of the above.
  • OK but clearly you’ve never heard of intersex or trans people. Women can have a Y chromosome and men don’t necessarily need one. This is the case much more often than you think. Also, as I understand it, you can sometimes inherit mtDNA from your father (quite obvious if the father is trans and gave birth to you) but this is rare and likely leads to health problems.

  • Gary Stephenson

    Follow up: The correct answer is not always C. Paternal mtDNA has been found in IVF offspring because the shovel the entire sperm, tail and all, into the egg, like so much coal into a furnace, and not all the male mtDNA gets rejected. So clueless again. I am going to recommend that an genetic internet company might want to surf the web now and then – just a suggestion for your box.