16.4 Sexual reproduction in humans

The named parts of the male reproductive system (testes, scrotum, sperm ducts, prostate gland, urethra, penis) and female reproductive system (ovaries, oviducts, uterus, cervix, vagina) with their functions. Fertilisation as the fusion of sperm and egg nuclei in the oviduct. Adaptive features of sperm (flagellum, mitochondria, acrosome enzymes) and egg cells (energy stores, jelly coat that changes at fertilisation). Comparison of male and female gametes by size, motility, and number. Embryonic development from zygote to a ball of cells that implants in the uterus lining. Fetal support structures: umbilical cord, placenta, amniotic sac, and amniotic fluid. HL extension: detailed function of the placenta and umbilical cord in materials exchange (O₂, glucose, amino acids in; CO₂, urea out — without blood mixing) and the warning that some pathogens and toxins can also cross the placenta.