(a) Testis is the male reproductive organ in humans that produces sperms and also secretes the testosterone hormone. Important functions of testosterone are as follows: Stimulates the development, maturation and functioning of the male accessory sex organs like vas deferens and seminal vesicles Stimulates muscular growth, growth of facial hair, low pitch voice, sperm production, etc.
(b) (i) Fertilisation takes place in the fallopian tube (oviduct). (ii) Implantation of the fertilised egg occurs in the uterus. The embryo develops inside the mother’s body for about nine months. Inside the uterus, the outer tissue surrounding the embryo develops finger-like projections called villi. These villi are surrounded by uterine tissue and maternal blood. They provide a large surface area for the exchange of oxygen and nutrients. There is a special tissue called placenta embedded in the uterine wall. The embryo receives the oxygen and nutrients from the mother’s blood via the placenta. The waste material produced by the embryo is removed through the placenta.