CBSE Class 10 Science 2017 · Paper 31/1/C · Question 22

(a) (i) Ovary: it produces the female germ-cells (eggs); one egg is released every month by one of the ovaries. The ovaries also produce female hormones such as oestrogen. (ii) Fallopian tube (oviduct): it carries the egg from the ovary towards the uterus, and it is the site of fertilisation, where a sperm meets the egg. (iii) Uterus: the fertilised egg (zygote) gets implanted in its thick, blood-rich lining and develops there into the embryo and then the foetus, which is nourished through the placenta; at birth, rhythmic contractions of the muscles of the uterus push the baby out. (b) Structure: the placenta is a special disc-like tissue embedded in the uterine wall. On the embryo's side it has finger-like projections called villi; on the mother's side are blood spaces that surround the villi, so that a large surface area is available for exchange. The embryo is joined to it by the umbilical cord. Functions: glucose (food) and oxygen pass from the mother's blood to the embryo across the villi, and the wastes produced by the embryo, such as carbon dioxide, pass into the mother's blood to be removed. The two blood streams do not normally mix.