Step 1: Define Secondary Sexual Characteristics.
Secondary sexual characteristics are traits that develop during puberty and distinguish males from females but are not directly involved in reproduction. These characteristics are influenced by sex hormones, such as testosterone in males.
Step 2: Two Secondary Sexual Characteristics in a 15-year-old Boy.
Two examples of secondary sexual characteristics in a 15-year-old boy are:
1. {Growth of facial hair:} Boys start developing facial hair, such as a mustache and beard, as a result of increased testosterone production.
2. {Deepening of the voice:} The larynx grows larger during puberty, leading to a deeper voice. This is also a result of the increased levels of testosterone.