What are the functions performed by the testis in human beings?
The testis performs two primary functions in human beings. First, it is responsible for the formation of germ-cells or sperms. The testes are located outside the abdominal cavity in the scrotum because sperm formation requires a lower temperature than the normal body temperature.
Secondly, the testes are responsible for the secretion of the hormone testosterone. This hormone regulates the formation of sperms. Additionally, testosterone brings about changes in appearance seen in boys at the time of puberty, such as new hair-growth patterns, which act as signals of sexual maturation.
Explanation
The answer is derived directly from the textbook context under the section 'Male Reproductive System'. The context explicitly lists two functions: the formation of sperms (germ-cells) and the secretion of testosterone. It also details the significance of the scrotum's location for temperature regulation regarding sperm formation and the role of testosterone in puberty changes.