Inheritance of Sex

• How many pairs of chromosomes do humans contain?

  23 pairs
• What is the role of the sex chromosomes in humans?

  • Determine sex
  • One pair of chromosomes (XX for females, XY for males)
• What are the sex chromosomes for males?

  XY
• What are the sex chromosomes for females?

  XX
• How do gametes differ between males and females in terms of sex chromosomes?

  • Females produce gametes with only X chromosomes
  • Males produce gametes with both X and Y chromosomes
• What is the expected ratio of male to female offspring from a couple?

  1:1
• What factors influence the actual sex ratio of offspring in a couple?

  • Probability of gamete combination
  • Random chance in multiple births
• Why might a couple have several offspring of the same sex?

  Due to the probabilistic nature of sex chromosome combinations