Sex Determination in Humans

Question 1

Sex chromosomes

Answer 1

• XY chromosomes are sex chromosomes which determine biological sex
• male individuals are XY with one X chromosome and one Y chromosome (the Y chromosome is shorter than the X chromosome)
• female individuals are XX with two identical X chromosomes

Question 2

Explaining sex determination in humans

Answer 2

• sex is determined at fertilisation by the combination of sex chromosomes
• ovum from mother carrying X chromosome is fertilised by sperm cell carrying either an X or Y chromosome
• individuals with two X chromosomes will develop as female while individuals with one X chromosome and one Y chromosome will develop as males