Theory question 107
Reproduction in Animals(For candidates in Nigeria only)
(a)(i) What is placentation? (ii) Name two organs associated with the human placenta.
(b) State five functions of the human placenta.
(c) Write short notes on the following:
(i) viviparity; (ii) territoriality; (iii) seasonal migration.
Show the model answer
(a)(i) Placentation is the way the placenta forms and the embryo becomes attached to the wall of the uterus (in flowering plants: the arrangement of ovules on the ovary wall).
(ii) Uterus; umbilical cord (also amnion/embryo).
(b) Any five: passes food from mother to foetus; supplies oxygen; removes CO2 and urea from the foetus; passes antibodies to the foetus; keeps the two blood systems separate (protects from high maternal pressure); acts as a barrier to many germs and harmful substances; produces hormones (progesterone, oestrogen) that maintain pregnancy; anchors the foetus.
(c)(i) Viviparity: development of the young inside the mother's body, nourished by her through a placenta, and birth of live young, e.g. humans.
(ii) Territoriality: an animal or group claims and defends an area against others of the same species, for food, mates or breeding, e.g. the male agama lizard.
(iii) Seasonal migration: regular movement of animals from one region to another at certain seasons and back, for food, breeding or better climate, e.g. migratory birds, wildebeest.
Each short note needs a definition and an example.