Tennessee does not dictate when a child is responsible enough to hunt on their own outside of the juvenile season. There is no law that establishes that. QL
I'll clarify my answer a tad. Different regulations exist for hunting in WMA's, such as the following:
On all "Young-Sportsman Hunts," youths, ages 6-16, may participate but must be accompanied by an adult, 21 years of age or older, who must remain in a position to take immediate control of the hunting device. Adults cannot hunt except as indicated otherwise. Adults must comply with fluorescent orange regulations, as specified for legal hunters when accompanying Young Sportsmen on "Young-Sportsman Big Game Hunts," except as indicated.
5. Youths, ages 6-16, may participate on other big game WMA hunts, but must be accompanied by an adult, 21 years of age or older, who must remain in a position to take immediate control of the hunting device except as otherwise noted.