Final answer:
During puberty in adolescents, both primary (reproductive organs like the uterus and testes) and secondary sex characteristics (such as breasts in females and facial hair in males) develop as a result of hormonal changes, marking the onset of reproductive functionality.
Step-by-step explanation:
Changes During Puberty
When adolescents undergo puberty, both primary and secondary sex characteristics appear, and reproductive organs begin to function. During this biological process, primary sex characteristics such as the uterus and ovaries in females, and testes in males mature and become fully functional. Secondary sex characteristics, which include the development of breasts and hips in females and facial hair and a deepened voice in males, also become prominent. Triggered by hormonal changes, males experience spermarche and females experience menarche, marking the beginning of reproductive capability.
The process is governed by a complex set of hormonal signals that starts with the hypothalamus releasing gonadotropin-releasing hormone (GnRH). This in turn stimulates the anterior pituitary gland to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which directly affect the gonads. The gonads then produce sex hormones such as testosterone in males and estrogen in females, leading to further sexual development. The predictable sequence of these events, though the exact timing may vary between individuals, results in sexual maturity and the ability to reproduce.