Outline the process of spermatogenesis in humans.

Explain the structure and function of the placenta during pregnancy.

production of sperm/spermatozoa in the testes/seminiferous tubules;

first stage of sperm production requires divisions by mitosis;

cells then undergo a period of growth;

future sperm cells then undergo two meiotic divisions;

cells then differentiate to form sperm cells;

nourished by Sertoli cells number becomes haploid / chromosome number halved / 46 to 23 chromosomes;

embryonic/disc shaped structure that nourishes the developing embryo;

starts forming at implantation of the blastocyst/embryo;

embryonic tissue invades/grows into the uterine wall;

fetal capillaries exchange material with maternal blood/lacunae;

allows exchange of food/oxygen/antibodies from mother’s blood to fetus;

allows exchange of carbon dioxide/waste products from fetal blood to mother;

connected to the embryo/fetus by an umbilical cord;

placenta takes over hormonal role of ovary;

indication of time this happens / at approximately 12 weeks;

secretes estrogen/progesterone;

hormone secretion maintains pregnancy;

expelled from uterus after childbirth;

The process of spermatogenesis was well known.

Many candidates become confused between the amniotic sac and the placenta. Marks were lost for imprecise statements about what actually passes between the mother and fetus and how it is transferred.