This deep dive covers Sex Chromosomes within Sex Determination for GCSE Biology. Sex chromosomes and sex determination mechanisms It is section 1 of 11 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Sex Chromosomes
Humans have 23 pairs of chromosomes. The 23rd pair determines sex:
XX
Female
Female
XY
Male
Male
Practice questions for Sex Determination
What determines the sex of a human baby?
Use a genetic diagram to show how sex is inherited in humans.
Quick recall flashcards
How do you remember XX = female and XY = male?
XX: the two X's look like chromosomes that pair up perfectly — females have a matching pair. XY: the Y looks like a little man standing with arms out — males have the odd one out. 'Why are boys different? Because of Y!'
What sex chromosomes do females and males have?
Females: XX (two X chromosomes). Males: XY (one X and one Y chromosome). These are the 23rd pair of chromosomes in humans.