i. The functions of the following parts of human male reproductive system are:

a) Testis: Testis is the male reproductive organ located in the scrotum. The primary function is production of sperms (Seminiferous tubules are present in the testes where sperm is produced) and also controlling the male hormone testosterone that gives secondary sex characteristics to males at puberty like facial hair .

b) Vas deferens: This helps transport mature sperm from the testes (specifically the epididymis where sperms are stored) to the urethra to the ejaculatory ducts for ejaculation while secretions from the male accessory sex glands (seminal vesicles, prostate, bulbo-urethral glands) are collected forming semen.

c) Urethra: It is a tube extending from the urinary bladder, through the length of the penis to its external opening. It serves as a passage for urine. It also has the function of ejaculation semen during ejaculation.

d) Prostate: Prostate gland lies below the urinary bladder and surrounds the urethra. Prostate gland produces prostate fluid (alkaline) which is one of the components of the semen making up about 13-33% of the same.

ii) Two common pubertal changes that appear in human males are:

The vocal cords double in length resulting in lowered pitch in males, pubic hair develops, hair appears in face, chest etc. Sweat glands also develop in the armpit.