Inheritance of sex

• How many pairs of chromosomes do humans contain?

  23 pairs
• What is the purpose of the video mentioned in the study material?

  To describe the inheritance of sex
• What do the 22 pairs of chromosomes in humans contain?

  Genes that determine inherited characteristics
• What are the sex chromosomes in males?

  X and Y chromosomes
• What are the sex chromosomes in females?

  X and X chromosomes
• How many gametes does a woman produce in terms of sex chromosomes?

  All gametes have the X chromosome
• How are the gametes of a man different from those of a woman?

  Half of the man's gametes have X and half have Y
• If a couple has offspring, what are the possible combinations of sex chromosomes?

  XX for female and XY for male
• What is the average ratio of female to male offspring?

  1 to 1
• What does the study material say about the probabilities of offspring's sex?

  They are just probabilities and can vary in reality
• Where can students find questions on the inheritance of sex?

  In the revision workbook
• What are the key points about sex chromosome inheritance?

  • Males have XY chromosomes
  • Females have XX chromosomes
  • All female gametes carry X
  • Male gametes carry X or Y
  • Offspring can be XX (female) or XY (male)
  • Average ratio of female to male offspring is 1:1
  • Actual outcomes can vary